Question: A 55-year-old man presents to the emergency department with right knee pain. He woke last night with sudden-onset, sharp, 10/10 non-radiating pain in his right knee. He denies recent trauma and he has no known medical problems. He denies tobacco use and will often drink 6-8 beers or spirits on weekend nights. His temperature is 98.6°F (37.0°C), pulse is 90/min, blood pressure is 140/90 mmHg, respirations are 16/min, and oxygen saturation is 97% on room air. Physical exam reveals an erythematous, edematous right knee. Passive extension of the knee is limited by pain. Synovial fluid aspiration is performed and sent for analysis, which reveals 20,000 leukocytes/mm^3, and no organisms visualized. Microscopic examination of synovial fluid is shown in Figure A. Which of the following is the most likely diagnosis?

Answer: Gout

Explanation:
The patient’s sudden-onset knee pain with effusion and synovial fluid findings are characteristic of gout.

Gout is caused by monosodium urate crystal deposition in joint spaces, most commonly in the big toe, ankle, or knee. Crystal deposition in the joint space leads to an intense inflammatory reaction that causes severe pain and joint effusion. Gout is most commonly due to lifestyle factors including a diet high in red meat and alcohol. Medications that cause elevated uric acid levels (such as thiazide diuretics) may also play a role. Conditions resulting in high cell turnover and therefore excessive purine release such as hematologic malignancies may also lead to the development of gout. Patients typically present with sudden-onset, severe pain, erythema, and joint effusion. Synovial fluid analysis will reveal an elevated leukocyte count and negatively birefringent, needle-shaped crystals. Treatment of acute gout is with NSAID medications, colchicine, or steroids depending on presentation and patient-specific factors. Prevention of further attacks is centered around lifestyle changes such as avoidance of red meat and alcohol. Xanthine oxidase inhibitors such as allopurinol are also often used for prevention of further episodes.

Neogi discusses the management of acute gout. She comments that, while synovial fluid analysis is the gold standard of diagnosis, many physicians do not routinely perform it, instead relying on clinical judgment to diagnose gout. The differential diagnosis for a gout-like presentation includes pseudogout, septic arthritis, Lyme arthritis, reactive arthritis, and rheumatoid arthritis.

Figure A shows monosodium urate crystals, which appear as negatively birefringent, needle-shaped crystals under polarized light.

Incorrect Answers:
Answer B: Lyme disease may also presents as a monoarticular arthritis in later stages. However, a recent history of tick exposure and preceding flu-like illness would also be expected.

Answer C: Pseudogout presents similar to gout, but is caused by calcium pyrophosphate deposition. Crystals appear rhomboid shaped and are positively birefringent under polarized light.

Answer D: Septic arthritis typically has higher leukocyte counts (> 50,000/mm^3) in the synovial fluid with organisms visualized on gram stain. Fever would also be expected.

Answer E: Rheumatoid arthritis may present as a monoarticular arthritis with acute flairs. However, crystals visualized in synovial fluid are more suggestive of acute gout.

Bullet Summary:
Acute gout presents with sudden-onset, severe joint pain and is characterized by needle-shaped negatively birefringent crystals visualized under polarized light.


Question: A 57-year-old woman presents to the emergency department for a headache. She was at home when a sudden headache began with greater severity than she had experienced in the past. She presented within 30 minutes of symptom onset. The patient has a medical history of sinusitis, constipation, diabetes, and pelvic inflammatory disease. Her current medications include fexofenadine, oral contraceptive pills, and metformin. She is currently taking amoxicillin for a sinus infection. She smokes 1 pack of cigarettes per day and drinks 2-3 alcoholic beverages daily. Her temperature is 99.5°F (37.5°C), blood pressure is 187/118 mmHg, pulse is 120/min, respirations are 17/min, and oxygen saturation is 98% on room air. On physical exam, the patient is noted to be uncomfortable with the appearance shown in Figure A. Neurological exam reveals a confused woman who is now complaining of "seeing double." Cardiopulmonary exam reveals mild bibasilar crackles and tachycardia. Abdominal exam is within normal limits. Which of the following is the most appropriate initial step in management?

Answer: Piperacillin-tazobactam

Explanation:
This patient is presenting with symptoms suggestive of septic cavernous sinus thrombosis (CST). The most appropriate initial step in management is urgent broad-spectrum antibiotics and surgical drainage.

Cavernous sinus thrombosis is an emergency that requires immediate intervention. It typically occurs in a patient with a history of sinusitis, oral contraceptive pill usage, smoking, or other risk factors that could cause a hypercoagulable state. These patients will often present with severe pain, a sudden headache, and diplopia. A distinct appearance is typically noted with periorbital edema. These patients should be immediately treated with broad-spectrum antibiotics and undergo surgical drainage of the inciting source of infection. In some cases, thrombolytics can be used as well.

Caranfa and Yoon review the evidence regarding the diagnosis and treatment of septic cavernous sinus thrombosis. They discuss how this diagnosis was almost universally fatal in the pre-antibiotic era. They recommend using broad-spectrum antibiotics and debridement to address this disease.

Figure/Illustration A is a clinical photograph demonstrating a face with swelling and periorbital edema (red circles). This appearance is classically seen in patients with CST.

Incorrect Answers:
Answer A: Amoxicillin-clavulanic acid would be appropriate management of acute otitis media or sinusitis; however, it is insufficient coverage for CST. Broad-spectrum antibiotics and surgical intervention are needed to prevent loss of vision.

Answer B: A CT scan of the head could be indicated potentially for surgical planning in a more stable patient; however, in this situation, immediate intervention is more dire. After antibiotics and stabilization, CNS imaging will be needed.

Answer C: Dexamethasone would be appropriate treatment of a relapse of multiple sclerosis, which can also present with visual changes; however, it would not present with sudden headache and periorbital edema.

Answer D: An MRI of the brain would be appropriate for further characterizing neurologic deficits of unclear etiology. In this case, the patient's acute presentation with neurologic changes secondary to CST requires immediate treatment rather than additional imaging.

Bullet Summary:
Cavernous sinus thrombosis should be immediately managed with broad-spectrum antibiotics and neurosurgery.


Question: A 29-year-old woman is recovering on the obstetrics floor after the vaginal delivery of 8-pound twin boys born at 42 weeks gestation. The patient is fatigued but states that she is doing well. Currently, she is complaining that her vagina hurts. The next morning, the patient experiences chills and a light red voluminous discharge from her vagina. She states that she feels pain and cramps in her abdomen. The patient's medical history is notable for diabetes which was managed during her pregnancy with insulin. Her temperature is 99.5°F (37.5°C), blood pressure is 107/68 mmHg, pulse is 97/min, respirations are 16/min, and oxygen saturation is 98% on room air. Laboratory values are obtained and shown below. Hemoglobin: 12 g/dL Hematocrit: 36% Leukocyte count: 9,750/mm^3 with normal differential Platelet count: 197,000/mm^3 Serum: Na+: 139 mEq/L Cl-: 101 mEq/L K+: 4.2 mEq/L HCO3-: 23 mEq/L BUN: 20 mg/dL Glucose: 111 mg/dL Creatinine: 1.1 mg/dL Ca2+: 10.2 mg/dL AST: 12 U/L ALT: 10 U/L Which of the following is the most appropriate next step in treatment for this patient?

Answer: Supportive therapy only

Explanation:
This patient is presenting with a normal postpartum period which is managed with supportive therapy only.

A normal postpartum period is associated with breast tenderness, chills, edema, and abdominal cramps from a contracting uterus. Vaginal discharge (lochia) is normal in this phase and progresses from a red color (lochia rubra) to a clear/fluid appearance (lochia serosa) to a white color (lochia alba). No management other than supportive therapy is needed during this period. Symptoms that indicate additional intervention may be necessary include fever, foul-smelling drainage, or hypotension.

Fletcher et al. review the evidence regarding normal lochia after pregnancy. They discuss how this discharge can occur for up to 24-36 days after delivery. They recommend understanding normal discharge patterns to allow for the identification of pathologic conditions.

Incorrect Answers:
Answer A: Cefoxitin and doxycycline can be used to treat postpartum endometritis in which the suspected organism is Chlamydia trachomatis or Neisseria gonorrhoea. Suspect these organisms in a patient with risky sexual behavior.

Answer B: Clindamycin and gentamicin offer broad-spectrum coverage for endometritis, which presents with fever, abdominal tenderness, and a foul-smelling vaginal discharge. This patient has no evidence of infection at this time.

Answer D: Vancomycin and clindamycin is not a typical broad-spectrum antibiotic pair that is used routinely. Both of these agents are often effective against MRSA but are typically not used concurrently.

Answer E: Vancomycin and gentamicin offer broad-spectrum antibiotic coverage and can be used for bacterial endocarditis which presents with fever and a new murmur in a high-risk individual (such as those who use IV drugs).

Bullet Summary:
A normal postpartum period presents with chills, abdominal cramps, and lochia (rubra, serosa, or alba) and is managed with supportive care.


Question: A 68-year-old woman presents to her primary care provider for dizziness. She often feels lightheaded and like she may “pass out” but never actually loses consciousness. She denies dyspnea on exertion or orthopnea. The patient had a myocardial infarction 6 months ago, and she now has multiple drug-eluting stents. Her ECG upon discharge from that hospitalization was normal. The patient has been taking all of her medications as instructed. Her medical history is otherwise significant for rheumatoid arthritis and migraines. Her home medications include methotrexate, atorvastatin, clopidogrel, and aspirin. Her temperature is 98.6°F (37°C), blood pressure is 118/75 mmHg, pulse is 92/min, and respirations are 12/min. On physical exam, she has an irregular heartbeat with normal cardiac sounds. Her abdomen is non-distended and she has mild lower extremity edema. Her current ECG can be seen in Figure A. Which component of the cardiac conduction system is most likely affected in this patient?

Answer: Atrioventricular node

Explanation:
This patient who presents with lightheadedness and is found to have progressive prolongation of the PR interval on ECG most likely has Mobitz type 1 (Wenckebach) 2nd-degree heart block. Mobitz type 1 heart block is usually caused by atrioventricular node dysfunction.

Second degree heart block can be divided into Mobitz type 1 and Mobitz type 2 patterns. The Mobitz type 1 pattern is usually a result of dysfunction at the atrioventricular (AV) node, whereas the Mobitz type 2 pattern is usually caused by dysfunction below the AV node in the His-Purkinje system. In Mobitz type 1 2nd-degree heart block, the PR interval becomes progressively longer with each beat before the dropped QRS complex. In Mobitz type 2 2nd-degree heart block, the PR intervals are consistent in length and the dropped QRS complexes occur at regular intervals. The easiest way to determine whether the PR interval is getting longer is to compare the PR interval just before the dropped beat to the PR interval immediately following the dropped beat. Patients with Mobitz type 1 blocks generally do not require treatment unless symptomatic whereas those with Mobitz type 2 blocks generally require pacemaker placement.

Clark and Prystowsky review the pathophysiology of heart block. They discuss how a type 1 2nd-degree heart block is caused by dysfunction of the atrioventricular node. They recommend symptomatic treatment of this condition.

Figure/Illustration A is an ECG that demonstrates the progressive prolongation of the PR interval (blue lines) until a beat is dropped. This progressive prolongation is characteristically seen in Mobitz type 1 (Wenckebach) heart block.

Incorrect Answers:
Answer B: A bundle branch block would produce a classic right or left bundle branch block pattern on ECG (RSR') described colloquially as "bunny ears." Bundle branch blocks are defined in part by a QRS duration > 120 ms and can be seen in lead V1. Treatment is with control of underlying risk factors such as hypertension.

Answer C: The bundle of His conducts the electrical impulse from the atrioventricular node to the ventricles. Dysfunction at the level of the bundle of His would more likely cause Mobitz type 2 2nd-degree heart block or 3rd-degree heart block rather than the Mobitz type 1 heart block seen in this patient. Treatment is with pacemaker placement.

Answer D: Purkinje fibers rapidly conduct along the ventricular walls to create synchronized contraction of the ventricles. Aberrant conduction of the Purkinje fibers leads to premature ventricular complexes. Treatment is with beta-blockers if patients are symptomatic.

Answer E: The sinoatrial node is the heart’s primary pacemaker. Dysfunction at this level can lead to sick sinus syndrome. Sick sinus syndrome can manifest as many types of arrhythmias, including bradycardia-tachycardia syndrome, in which there is alternating bradycardia with paroxysmal tachycardia. Sinoatrial node dysfunction can be treated with pacemaker placement.

Bullet Summary:
Mobitz type 1 (Wenckebach) 2nd-degree heart block is characterized by progressive prolongation of the PR interval before a dropped QRS complex and is usually caused by dysfunction of the atrioventricular node.


Question: A 62-year-old man presents to the emergency department with increased fatigue and changes in his vision. For the past month, he has felt abnormally tired and today noticed his vision is blurry. The patient also endorses increased sweating at night and new-onset headaches. He currently feels dizzy. The patient has a medical history of diabetes and hypertension. His current medications include insulin, metformin, and lisinopril. His temperature is 99.5°F (37.5°C), blood pressure is 157/98 mmHg, pulse is 90/min, respirations are 17/min, and oxygen saturation is 98% on room air. A cardiopulmonary exam is within normal limits. HEENT exam reveals non-tender posterior and anterior chain lymphadenopathy. Abdominal exam reveals splenomegaly and hepatomegaly. There are large, non-tender palpable lymph nodes in the patient's inguinal region. A neurological exam is notable for decreased sensation in the patient's hands and feet. He also complains of numbness and tingling pain in his extremities that has been persistent during this time. The dermatologic exam is notable for multiple bruises on his upper and lower extremities. Which of the following is most likely to be abnormal in this patient?

Answer: IgM

Explanation:
This patient is presenting with symptoms of hyperviscosity, fatigue, and organomegaly suggestive of a diagnosis of Waldenstrom macroglobulinemia (WM). WM is characterized by increased IgM production.

WM occurs secondary to a clonal B-cell that pathologically overproduces IgM. High levels of IgM can lead to symptoms of hyperviscosity including blurred vision, dizziness, headaches, and peripheral neuropathy. Organomegaly is a unique finding in WM and can present with hepatomegaly and splenomegaly. Other non-specific findings include fatigue, anemia, and lymphadenopathy. This disease can be diagnosed using protein electrophoresis, which would demonstrate a spike in the levels of IgM protein. Treatment can include plasmapheresis and rituximab.

Gertz et al. review the evidence regarding the diagnosis and treatment of patients with WM. They discuss how patients often present with organomegaly as well as symptoms of hyperviscosity. They recommend rituximab treatment in symptomatic patients.

Incorrect Answers:
Answers 1 & 2: Calcium and IgA/IgG can be elevated in multiple myeloma (MM). MM presents with fatigue, weight loss, bone pain (back pain in particular), and other non-specific findings. MM less commonly presents with symptoms of hyperviscosity and organomegaly and this phenomenon has been described primarily with the IgA subtype. This is a late phenomenon and would be unlikely without preceding symptoms of bone pain and weight loss as a substantial protein concentrations (>5 g/dL) are required for this phenomenon. Treatment is with systemic chemotherapeutic agents.

Answers 4 & 5: Natural killer cells and T-cells could be elevated in non-Hodgkin lymphoma which would present with fatigue, lymphadenopathy, and "B-symptoms" (e.g., night sweats and chills). It would not present with symptoms of hyperviscosity. Treatment is with multi-agent chemotherapy as well as possible local radiation therapy.

Bullet Summary:
Waldenstrom macroglobulinemia (hyper IgM syndrome) presents with symptoms of hyperviscosity, fatigue, and organomegaly.


Question: A 2-year-old boy is brought to the pediatrician’s office for a well-child visit. The parents have no concerns at this time and note he is starting to run around and speak in 3-word sentences. He has no remarkable medical history and his mother had an uncomplicated full-term pregnancy and delivery. He is appropriately meeting the developmental milestones for his age. The patient’s temperature is 98.4°F (36.9°C), blood pressure is 96/52 mmHg, pulse is 102/min, and respirations are 25/min. He is in the 55th percentile for height and 62nd percentile for weight, which is consistent with his documented growth curves. Fundoscopic exam shows the finding in Figure A. His pediatrician continues the ocular examination and further notes that the pupils are equal, round, and reactive, extraocular movements are full, and ocular alignment appears normal. Which of the following is the most appropriate next step in management?

Reevaluation at the next well-child visit

Answer: Ophthalmology referral

Explanation:
This otherwise healthy patient presents with leukocoria, or a white pupillary reflex, and requires an urgent referral to ophthalmology for further evaluation given the concern for retinoblastoma.

The differential diagnosis for leukocoria includes retinoblastoma, cataract, vitreous hemorrhage, retinal detachment, and other intraocular/systemic disease processes. Newly diagnosed leukocoria should be urgently referred to ophthalmology to exclude retinoblastoma. Retinoblastoma is the most common intraocular cancer of childhood caused by mutations in the RB1 tumor suppressor gene that encodes the retinoblastoma protein. Retinoblastoma typically presents as leukocoria in a child under the age of 3 with other signs including strabismus, nystagmus, or a red, inflamed eye. Treatment options include chemotherapy, laser photocoagulation, radiation, cryotherapy, and enucleation. Prompt diagnosis and treatment are important for optimal visual outcome and survival.

Francis et al. study the risk of extraocular extension in eyes with retinoblastoma that received intravitreous chemotherapy injections. The authors find that the risk of extraocular extension is small. The authors recommend the regular use of precautionary injection methods including lowering of intraocular pressure, cryotherapy, ocular surface irrigation, and ultrasonic biomicroscopy surveillance of the injection site.

Figure/Illustration A shows a child with leukocoria (blue circle) in the left eye.

Incorrect Answers:
Answer A: Biopsy of the eye is contraindicated in retinoblastoma due to the risk of tumor seeding.

Answer B: Genetic testing can be used to determine if a patient has the hereditary form of retinoblastoma, characterized by germline RB1 mutations, as opposed to the nonheritable form, which is associated with somatic RB1 mutations. An ophthalmological evaluation is required first to confirm the diagnosis.

Answer C: While magnetic resonance imaging of the brain and orbits should be performed in all children with suspected retinoblastoma to assess disease extent, an ophthalmological evaluation should be completed first.

Answer E: Reassurance or reevaluation at the next well-child visit is not appropriate management of newly diagnosed leukocoria given that undiagnosed retinoblastoma can be vision- and life-threatening.

Bullet Summary:
Leukocoria, or a white pupillary reflex, in a child requires urgent ophthalmologic referral to rule out retinoblastoma.


Question: A 27-year-old man presents to the emergency department after he developed pain in his right leg after landing off a ski jump. The patient is otherwise healthy and does not take any medications. He states his pain is 10/10. He is requesting medications and is crying out in pain. His temperature is 98.7°F (37.1°C), blood pressure is 149/85 mmHg, pulse is 103/min, respirations are 15/min, and oxygen saturation is 99% on room air. Physical exam reveals swelling over his right leg and knee. The patient cries out in pain with passive motion of the foot at the ankle. A radiograph is performed as seen in Figure A. Which of the following is the most likely diagnosis?

Answer: Tibial plateau fracture

Explanation:
This patient is presenting after an axial load on his lower extremity (landing off a ski jump) with severe pain, a fracture on radiography, and severe pain with passive range of motion. This suggests compartment syndrome in the setting of a tibial plateau fracture.

Tibial plateau fractures occur as a result of an axial load, where the femur forcefully impacts the tibia, leading to intense pain in the proximal tibia region. One potential complication of this type of fracture is compartment syndrome, which presents with exquisite pain out of proportion to exam with passive motion of the lower extremity. While radiography can aid in diagnosing tibial plateau fractures, a negative radiograph should prompt further investigation with a CT scan in patients with a high suspicion of this type of fracture. Treatment involves performing a fasciotomy if compartment syndrome is present. Surgical repair is warranted if there is evidence of neurovascular compromise or a significantly displaced fracture. Otherwise, immobilizing the knee and providing outpatient orthopedic follow-up care is deemed appropriate for certain less severe fractures.

Schneiderman et al. studied compartment syndrome in high-energy tibial plateau fractures. The authors found that younger patients aged 12-29 years old are more likely to develop compartment syndrome, likely due to increased muscle mass and thicker fascial tissue. The risk of deep surgical site infection remains high at 20-25% of cases. The authors recommend that clinicians should be aware of factors associated with increased risk for compartment syndrome, including young age, male gender, and a high-energy mechanism of injury.

Figure/Illustration A is a radiograph demonstrating a tibial plateau fracture with the red arrows demonstrating a fracture of the tibial plateau.

Incorrect Answers:
Answer A: Anterior cruciate ligament tear would present with a sudden popping sensation of the knee with swelling, knee instability, and laxity to anterior traction when force is applied to the tibia causing anterior displacement of the tibia relative to the femur. Management involves assessment with MRI and surgical repair in complete tears or immobilization in partial tears.

Answer B: Apophysitis of the tibial tubercle (Osgood-Schlatter disease) is common in pediatric patients and presents after exertion (such as basketball or jumping) with pain and tenderness over the tibial tubercle. It is caused by repeated microtrauma or microavulsion, separation of the proximal patellar tendon from the tibial tubercle, and subsequent callous deposition at the tibial tubercle. Management involves rest, ice, and nonsteroidal anti-inflammatory drugs.

Answer C: Patellar fracture would present with tenderness over the patella with a fracture line on the patella. Treatment of non-displaced fractures includes rest and immobilization in a straight-leg knee immobilizer.

Answer D: Posterior dislocation of the knee presents with sudden trauma to the knee with pain, swelling, and a loss of pulses in the extremity when the popliteal artery is compromised. Radiography is diagnostic and will show a knee dislocation. Treatment involves immediate reduction to avoid permanent injury to the popliteal artery.

Bullet Summary:
Tibial plateau fractures present after trauma with severe lower extremity pain and are highly associated with compartment syndrome.


Question: A 62-year-old man presents to the emergency department with skin lesions. He felt itchy recently, then noticed skin lesions that broke out prompting him to come to the emergency department. He recently went camping and hiking in the woods. The patient drinks 1-2 beers per day and smokes 1 pack of cigarettes per day. He is currently sexually active with multiple partners and does not use condoms. The patient was discharged 1 week ago for pneumonia which was treated with azithromycin; however, he feels that his symptoms may be returning. His temperature is 99.5°F (37.5°C), blood pressure is 157/78 mmHg, pulse is 90/min, respirations are 15/min, and oxygen saturation is 98% on room air. Physical exam reveals the findings in Figure A on the patient's arm. The skin lesions are thick and do not break when pressure is applied. Which of the following most appropriately describes the most likely diagnosis?

Answer: Linear IgG along the basement membrane

Explanation:
This patient is presenting with pruritic bullous skin lesions with a thick/tough covering suggesting a diagnosis of bullous pemphigoid. Linear IgG binding of anti-hemidesmosome antibodies along the basement membrane is the underlying cause of this disease.

Bullous pemphigoid presents with a urticarial prodrome in elderly patients followed by the formation of tense bullae that do not break when pressure is applied to them. IgG antibodies bind the hemidesmosome along the basement membrane and appear linear on immunofluorescence. Risk factors that are associated with this condition include the initiation of new medications such as loop diuretics, metformin, and neuroleptics. Steroids are the treatment of choice.

Miyamoto et al. review the evidence regarding the diagnosis and treatment of bullous pemphigoid. They discuss how high-potency corticosteroids are the mainstay of treatment for this disease. They recommend considering adjuvant therapy with doxycycline, dapsone, and immunosuppressants.

Figure/Illustration A is a clinical photograph showing bullous skin lesions (red circles). These lesions are tense and do not separate/break when pressure is applied to them and are classically seen in bullous pemphigoid.

Incorrect Answers:
Answer A: IgG in a fish-net pattern suggests a diagnosis of pemphigus vulgaris, which presents with skin lesions that are flaccid and break easily when pressure is applied. Treatment is with corticosteroids.

Answer C: Multi-nucleated giant cells suggests a diagnosis of HSV or herpes zoster virus, which presents with potentially painful vesicles distributed in a dermatomal pattern (for zoster). Treatment is with antivirals such as valacyclovir.

Answer D: Panniculitis suggests a diagnosis of erythema nodosum, which presents with painful, raised nodules that are associated with inflammatory disorders and infection. Treatment is centered on addressing the underlying pathology.

Answer E: Type IV hypersensitivity reaction suggests a diagnosis of contact dermatitis, which presents with pruritic lesions after exposure to a particular antigen such as poison ivy, poison oak, or nickel. Treatment is avoidance of the precipitating agent and steroids as well as symptomatic control.

Bullet Summary:
Bullous pemphigoid occurs secondary to anti-hemidesmosome antibodies which appear linear along the basement membrane on immunofluorescence.


Question: A 37-year-old woman presents to her physician for mood changes and recent falls over the course of 3 months. She feels more irritable with her husband and children and does not find pleasure in creating art anymore. Over the last 2 weeks, she has been sleeping approximately 5 hours a night and had a fall while walking in her home with the lights off. She denies any head trauma or loss of consciousness associated with the fall. She has a medical history of generalized anxiety disorder and hypothyroidism for which she takes escitalopram and levothyroxine. She had a Roux-en-Y gastric bypass 5 years ago. She has been in a monogamous relationship with her husband for the last 15 years and uses a copper intrauterine device. Physical examination is notable for a depressed affect. Pupils are equal, round, and reactive to light and accommodation. She has 4/5 strength in the bilateral lower extremities and brisk patellar reflexes. Which of the following is most likely the cause of this patient's symptoms?

Answer: Reduced functional parietal cell count

Explanation:
This patient's mood changes and findings concerning for subacute combined degeneration (fall in the dark, impaired proprioception, weakness, and brisk patellar reflexes), and history of Roux-en-Y gastric bypass surgery are concerning for vitamin B12 deficiency. Roux-en-y gastric bypass reduces parietal cell count, leading to reduced intrinsic factor secretion, which is needed for vitamin B12 absorption.

Roux-en-Y gastric bypass is a laparoscopic bariatric procedure that creates a small gastric pouch from the stomach with a gastrojejunal and jejunojejunal anastomosis. This causes small volumes of food to be consumed and decreases nutrient absorption. The small gastric pouch contains very few parietal cells, which decreases hydrochloric acid and intrinsic factor secretion. The reduced intrinsic factor secretion impairs the protection of vitamin B12 against HCl and reduces absorption in the ileum. Vitamin B12 deficiency can lead to neuropsychiatric changes (depressed mood, irritability, and insomnia) and subacute combined degeneration (weakness, sensory ataxia, peripheral neuropathy, and upper motor neuron signs). Patients who undergo Roux-en-Y gastric bypass must be given high doses of vitamin B12 (often intramuscularly) in order to prevent deficiency.

Alexandrou et al. review long-term micronutrient deficiencies after sleeve gastrectomy and Roux-en-Y gastric bypass (RYGB). The authors find that vitamin B12 deficiency was significantly higher in patients with RYGB compared with sleeve gastrectomy. The authors recommend adherence to supplemental iron and vitamin intake in all patients who undergo bariatric surgery.

Incorrect Answers:
Answer A: Poor iron absorption is a well-known complication of Roux-en-Y gastric bypass surgery due to bypass of the duodenum and proximal jejunum. Poor iron absorption leads to microcytic anemia from iron deficiency and presents with generalized fatigue and conjunctival pallor. Iron deficiency anemia would not present with brisk reflexes and impaired proprioception.

Answer B: Prior Treponema pallidum exposure can result in tabes dorsalis, a neurological complication of syphilis, and is seen in patients with a history of multiple sexual partners who do not use barrier protection. The spirochete leads to disease in the posterior columns (vibration and proprioception sensation). Patients present with sensory ataxia (similar to subacute combined degeneration), lancinating pain (in the limbs, back, or face), and an Argyll-Robertson pupil (impaired pupillary constriction to light but intact pupillary constriction to accommodation).

Answer C: Reduced central nervous system dopamine and serotonin are seen in patients with major depressive disorder which does not cause sensory ataxia with brisk reflexes.

Answer E: Subtherapeutic levothyroxine dose would result in hypothyroidism, which can present with depressed mood, cold intolerance, bradycardia, and delayed relaxation of deep tendon reflexes. Roux-en-Y is an effective means of losing weight, and as the body mass decreases with weight loss, the required dose of levothyroxine is decreased. It would not present with the abnormal neurologic findings seen in this patient.

Bullet Summary:
Roux-en-Y bariatric surgery increases the risk of vitamin B12 deficiency via reduction of food intake, decreased functional parietal cell count, and reduced absorption of vitamin B12 (which may cause subacute combined degeneration).


Question: A 51-year-old man presents to the emergency department complaining of fever and a cough with yellow-green sputum for the past 3 days. He denies any hemoptysis, facial pain, rhinorrhea, or night sweats. The patient reported similar symptoms 2 months ago. Chest radiograph performed at the time was notable for a right middle lobe consolidation. He was diagnosed with lobar pneumonia and completed a 7-day course of antibiotics with complete resolution of his symptoms. He has no other significant medical history and does not take any medications. He has smoked 1 pack of cigarettes a day for 35 years and drinks 3 beers per week. He is sexually active with his wife. His temperature is 101.7°F (38.7°C), blood pressure is 127/85, pulse is 102/min, and respirations are 22/min. Physical exam is notable for decreased breath sounds on the right side without wheezing and increased dullness to percussion on the right side. A chest radiograph is ordered and reveals a consolidation in the right middle lobe. Which of the following is the most appropriate next step in management?

Answer: CT of the chest without contrast

Explanation:
This patient's presentation with recurrent pneumonia in the same anatomical location is concerning for an anatomic abnormality. Given his history of heavy smoking, lung cancer should be ruled out with a chest CT with possible subsequent bronchoscopy for tissue biopsy.

Recurrent pneumonia can be classified either as those confined to 1 anatomical location of the lung or those involving different portions of the lung. If recurrent pneumonia is limited to a single region, the patient should be evaluated for an anatomic obstruction, such as a mass or mucous plug. Obstruction will hinder mucociliary clearance and allow for the proliferation of bacteria, leading to recurrent infections. The most concerning etiology of such an obstruction is a tumor causing external bronchial compression. Thus, patients should be screened with a chest CT to rule out lung cancer in these cases. If lesions are identified on CT, subsequent bronchoscopy or CT-guided biopsy may be warranted. Treatment may involve radiotherapy, chemoimmunotherapy, or surgery depending on the underlying malignancy. Other causes of recurrent pneumonia limited to an anatomical region include recurrent aspiration secondary to tracheoesophageal disorders or seizures.

Purysko et al. discuss the role of contrast enhancement in chest CTs. The authors find common indications for contrast-enhanced chest CTs include investigation for pulmonary embolism, pleural pathology, or hilar pathology. The authors recommend against the regular use of contrast enhancement in chest CTs outside of selected indications as they rarely provide additional diagnostic benefits while subjecting the patient to the risk of adverse effects with contrast agents.

Incorrect Answers:
Answer A: Barium swallow is often done to investigate anatomical abnormalities of the upper gastrointestinal tract such as tracheoesophageal fistula or Zenker diverticulum. These can increase the risk of aspiration and lead to recurrent pneumonia. In a patient with positive risk factors for cancer, chest CT to rule out malignancy would be the most appropriate next step.

Answer C: Human immunodeficiency virus (HIV) can cause secondary immunodeficiency, which can predispose patients to recurrent infections. These recurrent pneumonias would be expected to be in different regions of the lung and not anatomically confined.

Answer D: Interferon-gamma release assay can be used to diagnose tuberculosis (TB). Reactivation of TB will present clinically with fever, cough, hemoptysis, and night sweats. Chest radiography will commonly reveal an upper lobe infiltrate.

Answer E: Serum immunoglobulin levels would be an appropriate next step to diagnose primary immunodeficiencies such as common variable immunodeficiency or other antibody defects. This would present with multiple lung infections in different regions of the lung. Moreover, these patients would be expected to have other infections such as sinusitis, otitis, and gastrointestinal infections.

Bullet Summary:
Recurrent pneumonia in the same anatomical region should be worked up with a CT with subsequent bronchoscopy and biopsy to rule out malignancy.


Question: A 33-year-old man presents to the emergency department after slamming his finger in the car door 5 hours ago. He initially experienced pain which is currently well controlled with acetaminophen. The patient is otherwise healthy and does not take any medications. His temperature is 98.5°F (36.9°C), blood pressure is 123/79 mmHg, pulse is 90/min, respirations are 11/min, and oxygen saturation is 97% on room air. Physical exam is notable for the finding in Figure A. A radiograph of the affected digits shows a smooth cortex without disruption of the bone. Which of the following is the most appropriate management for this patient?

Answer: Trephination

Explanation:
This patient is presenting after trauma to his finger with a subungual hematoma. Given that he has no other associated injuries, trephination is the only management indicated.

A subungual hematoma occurs after trauma to the finger leading to a collection of blood under the fingernail. Depending on the mechanism, this can be associated with a distal phalanx fracture. Evaluation for a fracture should include a thorough history, exam, and radiography. If there are no other signs of injury including nailbed dislocation or an open fracture, then management requires only trephination (putting a hole in the nail to allow blood to drain) as this alleviates pressure on the nailbed matrix thus preventing possible irreversible damage.

Rsoer et al. compare nail bed repair to nail trephination for subungual hematomas in children. The authors find that there was no difference in complications or outcomes between nail bed repair and trephination; however, the cost in the nail trephination group was lower. The authors recommend nail trephination for children with a subungual hematoma and an intact nail and nail margin.

Figure/Illustration A shows the physical exam finding of a subungual hematoma with a collection of blood underneath the fingernail bed (green circle).

Incorrect Answers:
Answer A: Excision and histological examination could be appropriate management of melanoma, which may present under the fingernails with a hyperpigmented, irregular skin lesion, or a “barcode” appearance if it is at the base of the nail. A spontaneous subungual hematoma could be suggestive of melanoma; however, in the setting of trauma, it is a much less likely diagnosis.

Answer B: Fingernail removal should only be performed if there is also nail avulsion or nail fold disruption to allow for inspection of the nail bed and repair of any laceration. Failure to repair a nailbed laceration could lead to permanent deformity of the fingernail when it regrows.

Answer C: Observation is inappropriate as the accumulation of blood under the nail in a subungual hematoma could lead to ischemia and permanent injury to the nailbed. When a subungual hematoma is present, trephination is indicated.

Answer D: Operative repair may be necessary for fractures; however, this patient has no fracture and only has a subungual hematoma which can be drained easily.

Bullet Summary:
A subungual hematoma is common after trauma, presents with a collection of blood under the fingernail, and should be treated with trephination.


Question: A 69-year-old man presents to clinic due to shortness of breath, worsening pain in his right shoulder, and episodes of hemoptysis. His symptoms began 3 months ago. He has also lost 18 pounds. He has a history of coronary artery disease and underwent an uncomplicated coronary angioplasty with stent placement 2 years ago. He routinely travels both domestically and internationally as a senior shipyard worker and has a 30-pack-year smoking history. He used to drink 4 cocktails a week. He has not smoke or drank alcohol in over 7 years. His temperature is 99.5°F (37.7°C), blood pressure is 140/60 mmHg, pulse is 97/min, and respirations are 13/min. Physical exam is notable for right pupillary constriction as well as paresthesias in his right fourth and fifth digits. There is no pain with active shoulder rotation. His chest imaging is shown in Figure A. Which of the following is most likely responsible for the patient’s symptoms?

Answer: Lung adenocarcinoma

Explanation:
This elderly patient with an extensive smoking history is presenting with hemoptysis, weight loss, and shortness of breath. Combined with neurological findings in the ulnar nerve distribution (paresthesias in fourth and fifth digits) and imaging evidence of a superior right lung mass, the most likely diagnosis is a Pancoast tumor, which is most commonly a lung adenocarcinoma.

A Pancoast tumor is a peripheral lung cancer often caused by lung adenocarcinoma or squamous cell carcinoma and is often located in the superior sulcus of the lung. The most important risk factor is smoking. This tumor causes compression of adjacent structures. Patients can present with severe, localized axilla pain (due to invasion of the brachial plexus), weakness of intrinsic hand muscles with radicular pain and paresthesias in the fourth and fifth digits (due to invasion of the C8-T1 portion of the brachial plexus), Horner syndrome (miosis, ptosis, and facial anhidrosis due to invasion of the cervical sympathetic nerves), hoarseness (due to invasion of the recurrent laryngeal nerve), and edema of the arm with facial swelling (due to compression of the superior vena cava). Treatment is varied and involves a combination of radiation, chemotherapy, and surgery.

Wu et al. studied the role of the tyrosine-kinase inhibitor, osimertinib, in the treatment of completed resected epidermal growth factor receptor (EGFR)-mutated non-small cell lung cancer (NCSLC). The authors find that 89% of patients in the osimertinib group and 52% of the placebo groups were alive and disease free at 24 months. The authors recommend the use of osimertinib in patients with stage IB to IIIA EGFR-mutated NSCLC.

Figure/Illustration A demonstrates a right apical lung mass found on computed tomography (CT) scan (green arrow).

Incorrect Answers:
Answer B: Mesothelioma is a neoplasm of the pleura found in people with occupational exposures to asbestos, such as shipyard workers. While this neoplasm can present with hemoptysis and dyspnea, chest imaging of mesothelioma reveals pleural plaques and thickening, not an isolated apical lung lesion.

Answer C: Rotator cuff tendinopathy presents with pain with abduction and external rotation of the arm. This patient has no pain with active shoulder rotation.

Answer D: Syringomyelia is a cyst or cavity in the spinal column that can cause Horner syndrome and fluctuating radicular pain. It is unlikely to cause hemoptysis, weight loss, and the chest imaging findings in this patient.

Answer E: Tuberculosis is a possible diagnosis in this patient with hemoptysis, weight loss, and extensive travel history. Tuberculosis often presents with a fever and does not usually cause shoulder pain.

Bullet Summary:
Pancoast tumor presents with shoulder pain, cervical radiculopathy, Horner syndrome, and hoarseness and should be suspected in a patient with a smoking history and an apical lung mass on imaging.


Question: A 27-year-old man presents to the emergency department with altered mental status. He was running a marathon but became confused halfway through the race. He arrives unable to coherently answer questions and is not sure where he is. He has a history of a seizure disorder. His temperature is 105°F (40.6°C), blood pressure is 116/68 mmHg, pulse is 167/min, respirations are 29/min, and oxygen saturation is 99% on room air. Physical exam reveals a confused man who is moving all 4 extremities and is protecting his airway. During the exam, he develops a tonic-clonic seizure, which lasts 1 minute and then terminates on its own. The patient is given intravenous fluids, and basic laboratory studies are drawn and pending. A urine dipstick is positive for red blood cells. Which of the following is most likely to be seen on laboratory testing?

Answer: Hypocalcemia

Explanation:
This patient is presenting after running a marathon with hyperthermia and altered mental status suggestive of heatstroke. In the setting of his recent exertion, tonic-clonic seizure, and urine dipstick positive for red blood cells, he is likely suffering from rhabdomyolysis, which most commonly causes hypocalcemia.

Rhabdomyolysis occurs when there is a breakdown of the muscle cells. It can occur with exertion (such as marathon running or weight lifting), seizures (from prolonged and intense contraction of the muscles), cocaine use, lightning strikes, electrical injuries, and crush injuries. Damage to muscle cells most commonly causes hypocalcemia from the deposition of calcium in necrotic muscle cells as well as calcium sequestration by the muscle sarcoplasmic reticulum. Symptoms of hypocalcemia include perioral numbness and tetany, altered mental status, and seizure. ECG manifestations of hypocalcemia include QT prolongation. There is no treatment needed for hypocalcemia in rhabdomyolysis unless it is severe or is causing symptoms such as seizure or ECG changes. The management of rhabdomyolysis involves aggressive IV fluid administration titrated to urine output in order to prevent myoglobin nephrotoxicity. Myoglobin causes the classic false-positive finding of red blood cells on urine dipstick given the cross-reactivity of myoglobin and hemoglobin on this test.

Giannoglou et al. review the pathophysiology and diagnosis of rhabdomyolysis. The authors find that hypocalcemia is the most common electrolyte derangement seen in rhabdomyolysis. The authors recommend carefully monitoring ionized calcium in patients with rhabdomyolysis.

Incorrect Answers:
Answer A: Hyperkalemia is a common electrolyte derangement that occurs in rhabdomyolysis and can cause life-threatening dysrhythmias. Initial ECG findings suggestive of hyperkalemia include peaked T waves and QRS widening. The management of hyperkalemia involves the administration of calcium chloride to stabilize cardiac membranes followed by insulin, albuterol, and bicarbonate. Severe/refractory hyperkalemia can be treated with dialysis, but this is usually not needed in rhabdomyolysis. Hyperkalemia is less common when compared to hypocalcemia in rhabdomyolysis and does not cause seizures.

Answer B: Hyperphosphatemia is common in rhabdomyolysis and occurs secondary to the release of phosphorus from damaged muscle cells. Hyperphosphatemia does not usually require treatment in rhabdomyolysis, though phosphate restriction and phosphate binders can be administered. Hyperphosphatemia can rarely lead to seizures, though this is uncommon.

Answer C: Hyperuricemia is possible in rhabdomyolysis, occurs secondary to the release of purines from injured muscle cells, and is worsened by acute kidney injury which is common in rhabdomyolysis. The treatment of hyperuricemia in rhabdomyolysis involves IV fluids, rasburicase, and allopurinol (which works slowly).

Answer E: Hyponatremia may occur after running a marathon where the individual sweats out sodium, chloride, and water but rehydrates with only water. While this is possible in this patient and his seizure could reflect a hyponatremic seizure (which usually would not spontaneously resolve and requires hypertonic saline), there is concrete evidence of rhabdomyolysis with the positive urine dipstick for red blood cells.

Bullet Summary:
Rhabdomyolysis can cause hyperkalemia, hyperphosphatemia, and hypocalcemia (the most common electrolyte disturbance).


Question: A 7-year-old boy is brought to the emergency department by his parents for worsening symptoms of previously diagnosed acute sinusitis. Initially, the pediatrician prescribed decongestants and sent the patient home. Since then, the patient has developed a nasal discharge with worsening pain. The patient has a medical history of asthma which is well-controlled with albuterol. His temperature is 99.5°F (37.5°C), blood pressure is 90/48 mmHg, pulse is 124/min, respirations are 17/min, and oxygen saturation is 98% on room air. The cardiopulmonary exam is within normal limits. Inspection of the patient's nose reveals a unilateral purulent discharge mixed with blood. The rest of the patient's exam is within normal limits. Which of the following is the most likely diagnosis?

Bleeding and infected vessel of Kiesselbach plexus

Answer: Foreign body obstruction

Explanation:
This patient presents with unilateral bloody/purulent discharge from the nose suggesting a diagnosis of a nasal foreign body.

The most common cause of unilateral nasal symptoms in a pediatric patient is a nasal foreign body. Nasal foreign bodies tend to be unilateral (though bilateral symptoms are plausible) and present with a purulent and bloody discharge. The treatment of choice is to remove the object which may be done in the emergency department or operating room depending on how deep the object is. Visualization of the object should be attempted when possible in order to allow for safe retrieval.

Krulewitz and Fix review the evidence regarding the diagnosis and treatment of patients with epistaxis. They discuss how foreign body insertion is a major risk factor for the development of epistaxis. They recommend assessment of airway and breathing in the setting of severe epistaxis.

Incorrect Answers:
Answer A: A bleeding and infected vessel of the Kiesselbach plexus could suggest a complicated case of epistaxis. The persistent, unilateral symptoms in this patient point toward a different diagnosis. A high index of suspicion for foreign bodies should be suspected in children.

Answer C: Nasopharyngeal carcinoma tends to occur in young male patients and can be associated with infectious mononucleosis. Epistaxis can be a symptom and the mass can be visualized. This disease tends to present in older patients and is far less common than foreign bodies. Treatment is with surgical resection.

Answer D: Septal perforation can occur secondary to repeat cocaine use but would not present with unilateral nasal discharge in a pediatric patient. It would be highly unlikely in a pediatric patient with no history of drug use. Treatment is with cessation of the offending agent.

Answer E: Sinusitis with bacterial superinfection would typically present with systemic symptoms as well as bilateral symptoms. Though this diagnosis is possible, it is less likely than a foreign body. Treatment is with systemic antibiotic therapy.

Bullet Summary:
A nasal foreign body presents with unilateral bloody/purulent nasal discharge.


Question: A 57-year-old man presents to the emergency department for weight loss and abdominal pain. The patient has felt steadily more fatigued over the past month and has lost 22 pounds without effort. Today, he fainted prompting his presentation. The patient has no significant medical history. He does have a 33-pack-year smoking history and drinks 4 to 5 alcoholic drinks per day. His temperature is 99.5°F (37.5°C), blood pressure is 100/58 mmHg, pulse is 100/min, respirations are 17/min, and oxygen saturation is 98% on room air. The patient is very thin and appears pale. Stool fecal occult blood testing is positive. A CT scan of the abdomen is performed demonstrating a mass in the colon with multiple metastatic lesions scattered throughout the abdomen. The patient is informed of his diagnosis of metastatic colon cancer. When the patient conveys the information to his family, he focuses his efforts on discussing the current literature in the field and the novel therapies that have been invented. He demonstrates his likely mortality outcome which he calculated using the results of a large multi-center study. Which of the following is this patient most likely demonstrating?

Answer: Intellectualization

Explanation:
This patient is using facts and logic to emotionally distance himself from his stressful diagnosis. This ego defense method is suggestive of intellectualization.

Intellectualization typically occurs in patients who have received a very stressful diagnosis or bad news for a close loved one. They will often focus on the science and research of their disease rather than focus on emotionally processing this stressful event. This is a way of distancing themselves from the diagnosis and their circumstances. These patients may have difficulty connecting with others because they become extremely focused on data.

Arnold reviews the evidence regarding the diagnosis of intellectualization. He discusses how this term can either refer to the isolation of affect or the general use of reason. He recommends a better understanding of how this ego defense works.

Incorrect Answers:
Answer A: Dissociation is the detachment of the mind from the emotional state/body. A more specific diagnosis for this patient would be intellectualization as he is detaching himself from the emotional state of the diagnosis and instead focusing on the science behind his condition.

Answer C: Optimism is trying to find the best in a bad situation. This patient's focus on treatment outcomes and absence of emotion suggests intellectualization as the employed defense mechanism. Patients who are optimistic will still be able to emotionally process information.

Answer D: Pessimism is finding the worst in most situations. Pessimism would be a possible answer if the patient had a very treatable disease but thought that poor outcomes would occur regardless.

Answer E: Rationalization is the use of logic or reasoning (that can be inappropriate) in order to substantiate one's behavior even when it is inappropriate. An example is justifying theft because a person was in need.

Bullet Summary:
Intellectualization is the use of facts and logic to distance oneself from a stressful situation.


Question: A 56-year-old woman presents to the emergency department with muscle weakness. Her symptoms have progressively worsened over the course of 2 weeks and are most significant in her lower extremities. She also notices increased urinary frequency. Approximately 1 month ago, she was diagnosed with calcium phosphate nephrolithiasis. Medical history is significant for rheumatoid arthritis diagnosed approximately 10 years ago and treated with methotrexate as well as type 2 diabetes mellitus treated with metformin. Her temperature is 98.6°F (37°C), blood pressure is 138/92 mmHg, pulse is 92/min, and respirations are 17/min. On physical exam, there is mild tenderness to palpation of the metacarpophalangeal and proximal interphalangeal joints. There is 4/5 power throughout the lower extremity. Laboratory testing is shown. Serum: Na+: 137 mEq/L Cl-: 106 mEq/L K+: 2.9 mEq/L HCO3-: 18 mEq/L Glucose: 115 mg/dL Creatinine: 1.0 mg/dL Urine pH: 5.6 Which of the following is the most appropriate next step in management?

Administer intravenous sodium bicarbonate

Begin potassium replacement therapy with dextrose

Answer: Administer intravenous sodium bicarbonate

Explanation:
This patient's non-anion gap metabolic acidosis, hypokalemia, alkaline urine, and history of a calcium phosphate kidney stone and rheumatoid arthritis are suggestive of type 1 (distal) renal tubular acidosis. The treatment of choice is alkali replacement (sodium bicarbonate).

Type 1 (distal) renal tubular acidosis results from impaired acid (H+) secretion in the distal nephron. Impaired acid secretion decreases the kidney's ability to acidify the urine, thus increasing the urine pH. Impaired acid secretion also results in potassium wasting resulting in hypokalemia. Acidemia causes the bone to release calcium phosphate which buffers the acid. The alkaline urine along with decreased citrate excretion (caused by acidemia) leads to a favorable environment to form calcium phosphate stones. Therefore, correction of metabolic acidosis is essential in managing this condition.

Palmer et al. review the evidence regarding the treatment of renal tubular acidosis. They discuss how this disease can be divided into types based on the location of the deficit. They recommend using alkali therapy in patients with distal renal tubular acidosis.

Incorrect Answers:
Answer A: Administering hydrochlorothiazide would be a treatment option for type 2 (proximal) renal tubular acidosis. Patients with this condition can have associated hypokalemia but would be expected to have an acidic urine pH (less than 5.5) after significant bicarbonate excretion.

Answer B: Administering intravenous insulin would further decrease the serum potassium and place the patient at risk of developing cardiac arrhythmia. This patient's most important concern is her renal tubular acidosis that is resulting in muscle weakness from hypokalemia. Her polyuria is caused by hypokalemia, as it decreases the kidney's responsiveness to antidiuretic hormone. Her serum glucose is also not significantly elevated to cause osmotic diuresis.

Answer D: The dextrose (in the replacement therapy with potassium) would trigger the pancreas to secrete insulin and would lead to an intracellular shift of potassium. This would not particularly improve extracellular potassium levels. Treatment should be aimed at addressing the root of the patient's symptoms. Potassium citrate can be administered in cases of severe hypokalemia and hypokalemia that persists after correcting the serum bicarbonate level.

Answer E: Increasing the methotrexate dose is not appropriate in this case. The patient's muscle weakness is more suggestive of hypokalemia secondary to type 1 renal tubular acidosis. She does not report symptoms of inflammatory arthritis (joint pain/stiffness that is worse in the morning and improves with use).

Bullet Summary:
Type 1 (distal) renal tubular acidosis is treated with alkali replacement (sodium bicarbonate or sodium citrate).


Question: A 6-week-old boy is referred to a pediatric hematologist-oncologist for further evaluation following an abnormal newborn hemoglobinopathy screening. The father’s brother died of sickle cell anemia at an early age. Parental studies reveal that both mother and father are carriers of the sickle cell gene. The patient's temperature is 98.6°F (37.0°C), blood pressure is 80/45 mmHg, pulse is 130/min, and respirations are 25/min. The physician decides to repeat testing for the patient and his 3-year-old sister. The results are shown in Figure A. The physician begins counseling the family. Which of the following is the most likely complication that the patient may have in the future?

Answer: Hematuria

Explanation:
Based on the presence of both hemoglobin (Hb) A and S on gel electrophoresis, this patient has sickle cell trait. Episodes of painless hematuria are commonly seen in these patients.

Sickle cell trait is a condition that refers to carrying 1 normal and 1 abnormal beta-globin allele. On electrophoresis, this will present as 3 different bands consisting of about 50-60% HbA, 35-45% HbS, and < 2% HbF (fetal hemoglobin). HbF decreases significantly after the first 6 weeks of life. Individuals with sickle cell trait tend to be asymptomatic and do not have a decreased lifespan compared to the general population. However, they are at higher risk of some conditions. Patients are at increased risk of rhabdomyolysis during strenuous physical activity and may have episodic painless hematuria due to renal papillary necrosis. The hyperosmolar, acidotic, and hypoxic environment of the renal medulla is thought to trigger red cell sickling which results in ischemia and subsequent hematuria. Patients with sickle cell trait are managed similarly to the general population. These patients should receive reproductive counseling and use appropriate preventive measures to prevent dehydration during intensive exercise.

Hulsizer et al. studied the association between sickle cell trait and common medical conditions using insurance claims data. The authors found that sickle cell trait is associated with increased risks of diabetes, hypertension, heart disease, chronic kidney disease, and retinopathy. The authors recommend further evaluation of these associations using prospective studies derived from clinical data.

Figure/Illustration A shows gel electrophoresis with an example of a normal (95-98% HbA and < 2% HbF), sickle cell trait (50-60% HbA, 35-45% HbS, and < 2% HbF), and sickle cell anemia (85-95% HbS and 5-15% HbF) patient from left to right.

Incorrect Answers:
Answer A: Diabetes has not been associated with sickle cell trait in the majority of studies.

Answer C: Infection is a complication of sickle cell anemia. Mechanisms include functional asplenism, reduced tissue perfusion during a sickle crisis, and chronic transfusions with an indwelling catheter. Common infections include bacteremia, meningitis, and pneumonia due to Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitis. Sickle cell trait is not clearly associated with an increased risk of infection and actually confers some protection against malaria.

Answer D: Splenectomy from auto-infarction is often seen in sickle cell anemia, but it is rare with sickle cell trait. In sickle cell anemia, splenic sequestration of sickled red blood cells causes infarction, leading to progressive atrophy and functional hyposplenism. Most individuals with sickle cell disease are functionally asplenic by age 2 to 4. The spleen subsequently cannot phagocytose encapsulated organisms properly, which predisposes sickle cell patients to infection.

Answer E: Stroke is a complication of sickle cell anemia but not sickle cell trait. This is due to the increased viscosity of the blood and reduced deformability of red cells in patients with sickle cell anemia.

Bullet Summary:
Sickle cell trait is associated with episodes of painless hematuria.


Question: A 41-year-old man presents to his primary care provider with a 2-month history of abdominal pain. He says that the pain “comes and goes” throughout the day and usually lasts 20-30 minutes per episode. The pain is above his umbilicus. He denies any feeling of regurgitation or nighttime cough but endorses nausea. He used to eat 3 large meals per day but has found that eating smaller meals more frequently improves his pain. He tried ibuprofen with food and thinks it helped. He has gained 4 pounds since his last appointment 3 months ago. He denies any diarrhea or change in his stools. He has no known medical history. He drinks 5-6 beers on the weekend and has a 20 pack-year smoking history. He denies any family history of cancer. His temperature is 98.6°F (37°C), blood pressure is 117/72 mmHg, pulse is 72/min, and respirations are 13/min. On physical exam, he is tender to palpation above the umbilicus. Bowel sounds are present. A stool guaiac test is positive. The patient undergoes an endoscopy with a biopsy to diagnose his condition. Which of the following is most likely to be found on histology?

Noncaseating granulomas in the small intestine

Urease-producing organism in the small intestine

Answer: Urease-producing organism in the small intestine

Explanation:
This patient presents with episodic epigastric pain and nausea that improves with the consumption of food, which suggests a diagnosis of a duodenal ulcer. Duodenal ulcers are often caused by infection with Helicobacter pylori, a urease-producing organism.

Duodenal ulcers are erosions and defects in the mucosal lining of the small intestines that allow for damage to the underlying tissues. Patients will classically present with abdominal pain that is localized to the epigastric region. Duodenal ulcers improve upon eating due to the secretion of bicarbonate in the small intestines, whereas gastric ulcers are exacerbated by food due to the release of gastric acid in the stomach. Duodenal ulcers are most commonly caused by infection with H. pylori. If the patient tests positive for H. pylori infection, treatment involves triple therapy with amoxicillin, clarithromycin, and a proton pump inhibitor. Patients who fail to improve should undergo esophagogastroduodenoscopy, which remains the gold standard for diagnosis.

Ciociola et al. studied the prevalence of H. pylori infection in patients with gastric ulcers. They found that about many had confirmed infections. They recommend against empiric treatment without prior confirmation of infection.

Incorrect Answers:
Answer A: Crypt abscesses are found on histology in ulcerative colitis. Ulcerative colitis presents with bloody diarrhea and abdominal pain. Patients can also experience musculoskeletal pain, uveitis, and dermatologic findings such as erythema nodosum or pyoderma gangrenosum. Treatment may include mesalazine.

Answer B: A mucosal defect in the stomach is the pathologic description of a gastric ulcer. This patient’s presentation of epigastric pain that improves with the consumption of food is more consistent with an ulcer in the duodenum. Treatment of a gastric ulcer may include proton pump inhibitors.

Answer C: Noncaseating granulomas are found on histology in Crohn disease. This patient denies any diarrhea (often associated with pain), which is the primary feature of Crohn disease. Other findings include abscesses, fistulas, and strictures. Treatment may include mesalamine and infliximab.

Answer D: PAS-positive material is found in the lamina propria on small intestinal biopsy in Whipple disease. In addition to abdominal pain, Whipple disease is characterized by diarrhea with flatulence and steatorrhea, fever, arthralgias, and weight loss. Treatment is with ceftriaxone or penicillin.

Bullet Summary:
Duodenal ulcers typically present with episodic epigastric abdominal that is improved after eating and are associated with H. pylori infection.


Question: A 35-year-old man is brought into the emergency department by ambulance for a stab wound to the left leg near the inguinal ligament. The patient has no significant medical history, and takes no other medication. He was not stabbed or otherwise injured elsewhere. His temperature is 98.6°F (37.0°C), pulse is 130, blood pressure is 85/50, and respirations are 22. Primary and secondary survey and FAST exam are unremarkable for other associated injuries. Pressure is removed from the wound, and pulsatile bleeding from the wound is noted. Which of the following is the most appropriate next step in management?

Answer: Emergent surgical intervention

Explanation:
This patient with pulsatile bleeding from a wound to the left thigh and hemodynamic instability has hard signs of vascular injury. Patients with penetrating wounds and hard signs of vascular injury should be managed with emergent surgical intervention.

Vascular injury commonly occurs as a result of penetrating trauma, such as a stab wound as in this patient. Evaluation begins with a primary and secondary trauma survey to assess for other injuries. Hard signs of vascular injury include pulsatile bleeding, expanding hematoma, and absent pulses distal to the wound. For patients with suspected vascular injury that display either hard signs or hemodynamic instability, emergent surgical intervention is the most appropriate next step in management. For those with soft signs of vascular injury such as non-pulsatile bleeding or associated bony injury, the most appropriate next step in management is CT angiography of the affected limb.

Ball et al. discuss penetrating trauma to the extremities. They state that extremity trauma is the most common source of vascular injury (51%), with femoral artery as the most frequently injured vessel (35%). They also state that though obtaining pulses is important, distal pulses can continue to be present in many limbs with arterial injuries and therefore may require confirmatory evaluation via doppler, CT scan, or even angiography.

Incorrect Answers:
Answer A: Angiography of the left lower extremity may be utilized if this patient did not present with hard signs of vascular injury. However, this patient's presentation warrants emergent surgical intervention.

Answer B: CT scan of the left lower extremity may be utilized if this patient did not present with hard signs of vascular injury. This patient's presentation warrants emergent surgical intervention.

Answer D: Observation may be appropriate if this patient was hemodynamically stable, and showed no hard or soft signs of vascular injury.

Answer E: Wound closure may eventually be appropriate if this patient was hemodynamically stable, and showed no hard or soft signs of vascular injury.

Bullet Summary:
For patients with suspected vascular injury with hard signs of vascular injury the first step in management is emergent surgical intervention.


Question: A 67-year-old man is seen on the surgical floor after a transplant procedure. The previous day, the patient had a renal transplant from a matched donor. He is currently recovering and doing well. The patient has a medical history of IV drug use, diabetes mellitus, oral cold sores, hypertension, renal failure, and dyslipidemia. The patient's current medications include lisinopril, atorvastain, insulin, and aspirin. Prior to the procedure, he was also on dialysis. The patient is started on cyclosporine. The patient successfully recovers over the next few days. His temperature is 98.5°F (36.9°C), blood pressure is 121/76 mmHg, pulse is 70/min, and respirations are 13/min. Which of the following medications should be started in this patient?

Answer: TMP-SMX

Explanation:
This patient is presenting status post renal transplant and is currently on immunosuppressive therapy. This patient should be started on TMP-SMX as prophylaxis against Pneumocystis jiroveci pneumonia (PJP).

After a transplant procedure, patients are started on immunosuppressive therapy in order to avoid rejection of the transplanted organ. The most important interventions for a patient after a transplant procedure are to receive all of their vaccinations and to receive TMP-SMX as prophylaxis against PJP. Other appropriate but less dire measures include giving ganciclovir as prophylaxis against cytomegalovirus (CMV). Patients should be closely monitored to avoid transplant rejection as well as infection.

Weyant et al. review the evidence regarding the treatment of patients with PJP. They discuss how TMP-SMX has been the classic prophylaxis and treatment for this disease. They recommend considering echinocandins for patients who experience significant side effects.

Incorrect Answers:
Answer A: Azithromycin is appropriate prophylaxis for patients with HIV with CD4 counts < 50. Patients on immunosuppressive drugs should receive some of the same prophylactic medications but they do not require azithromycin upon initiation of immunosuppressive medications.

Answer B: Low-dose acyclovir would be an inappropriate intervention in this patient after a transplant procedure. Ganciclovir and high-dose acyclovir are the appropriate options for prophylaxis of CMV.

Answer C: Penicillin can be used as prophylaxis for patients with rheumatic heart disease or asplenia; however, it would not be the most appropriate initial measure in a transplant patient.

Answer E: Valacyclovir is the treatment for herpes simplex virus (HSV). It is not routinely indicated as prophylaxis in transplant patients. HSV will present with vesicular rashes developing on the affected areas.

Bullet Summary:
Patients on immunosuppressive therapy after a transplant should be vaccinated (pneumovax, hepatitis A and B, influenza, and tetanus-diphtheria) and started on TMP-SMX.


Question: A 17-year-old girl presents to the clinic reporting 7 months without a menstrual period. Menarche was at age 12 and she had regular periods up until 2 years ago. At that time, her periods became less regular until around 7 months ago when they ceased altogether. She is otherwise healthy, participates in multiple school sports teams, and has been training rigorously for upcoming competitions. She denies alcohol use, smoking, and recreational drugs. She is not sexually active and does not take oral contraceptives. Her temperature is 36.7°C (98°F), blood pressure is 121/80 mmHg, pulse is 62/min, respirations are 11/min, oxygen saturation is 100% on room air, and BMI is 20 kg/m^2. Her pelvic exam reveals an anteverted uterus, no adnexal masses, a normal-appearing cervix with no cervical motion tenderness, and normal vaginal anatomy. Which of the following is the most likely cause of this patient's amenorrhea?

Answer: Functional hypothalamic amenorrhea

Explanation:
This patient presenting with secondary amenorrhea (defined as 6 or more consecutive months without menstruation in women who have passed menarche) and a history of rigorous exercise most likely has functional hypothalamic amenorrhea.

Functional hypothalamic amenorrhea is a condition in which relative caloric deficiency (whether through severe caloric restriction, increased energy expenditure, or increased stress) leads to functional disruption of the normal pulsatile release of gonadotropin-releasing hormone (GnRH). This in turn leads to decreased levels of follicle-stimulating hormone (FSH) and luteinizing hormone (LH), disruption to estrogen levels, and amenorrhea. A common associated clinical presentation is known as the "female athlete triad", which includes decreased calorie availability or increased energy expenditure through exercise, decreased bone mineral density due to a decrease in estrogen levels, and menstrual dysfunction. Treatment includes increasing caloric intake, behavioral therapy as needed, and possible estrogen replacement therapy.

Ackerman et al. reviews the role of estrogen replacement in improving bone mineral density in patients with functional hypothalamic amenorrhea. The authors find that spine and femoral neck bone mineral density z-scores significantly increased with estrogen replacement. The authors recommend the use of transdermal estradiol over 12 months in improving bone mineral density in patients with functional hypothalamic amenorrhea.

Incorrect Answers:
Answer A: Anorexia nervosa will often manifest with secondary amenorrhea in women. This patient has a normal BMI and no history of disordered eating. The mechanism of amenorrhea in the setting of anorexia nervosa relates to the same hypothalamic-pituitary-ovarian axis at play in functional hypothalamic amenorrhea wherein the state of energy deficiency from inadequate caloric intake disrupts normal pulsatile GnRH secretion, leading to decreased FSH, LH, estrogen levels, and subsequent amenorrhea.

Answer C: Hypothyroidism is a cause of secondary amenorrhea wherein abnormal thyroid function can lead to altered levels of sex hormone-binding protein, prolactin, and gonadotropin-releasing hormone, thus causing menstrual dysfunction. This patient does not present with other signs of hypothyroidism, such as fatigue, sensitivity to cold, dry skin, muscle weakness, weight gain, constipation, joint stiffness, or thinning hair.

Answer D: Polycystic ovary syndrome is a condition often associated with obesity in which hyperinsulinemia or insulin resistance is hypothesized to alter the hypothalamus feedback response, leading to the increased luteinizing hormone to follicle-stimulating hormone ratio, increased androgen levels, and decreased rate of follicular maturation leading to unruptured follicles. Patients will often present with amenorrhea or oligomenorrhea, hirsutism, acne, and decreased fertility.

Answer E: Pregnancy is a cause of secondary amenorrhea that is less likely in this patient given her lack of sexual history and other associated symptoms such as decreased appetite, nausea, and insomnia. A beta-human chorionic gonadotropin (beta-hCG) test should always be part of the workup for secondary amenorrhea.

Bullet Summary:
Functional hypothalamic amenorrhea is a condition in which caloric restriction, increased energy expenditure through exercise, and/or increased stress leads to a disrupted pulsatile secretion of gonadotropin-releasing hormone with the downstream effect of amenorrhea.


Question: A 40-year-old south asian man presents to a primary care provider with a chronic cough that is worse at night. He has had the cough for several years but it has been getting worse over the last few months. He recently moved to the United States to work in construction. He has lost 10 pounds in the last 3 months along with darker stools which he believes is caused by a Western diet. He denies any difficulty swallowing or feeling of food getting stuck in his throat. He drinks alcohol 1-2 times per week and has never smoked. He denies any family history of cancer. His temperature is 98.6°F (37°C), blood pressure is 114/72 mmHg, pulse is 82/min, and respirations are 12/min. On physical exam, his lungs are clear to auscultation bilaterally without wheezing. His abdomen is soft and non-distended. He has no tenderness to palpation and bowel sounds are present. Which of the following is the most appropriate next step in management?

Answer: Upper endoscopy

Explanation:
This patient presents with a chronic cough that is worse at night, which is consistent with gastroesophageal reflux disease (GERD). In light of this patient’s new weight loss and melena, the most appropriate next step in management would be upper endoscopy to rule out cancer.

GERD may present as a chronic or nighttime cough, substernal or epigastric pain, regurgitation, nausea, or bitter taste in the mouth. Symptoms are typically worse after eating or lying down. Patients with typical GERD should undergo upper endoscopy if they have concerning symptoms, including dysphagia, odynophagia, vomiting, weight loss, gastrointestinal bleeding, or melena. They should also undergo upper endoscopy if they are men over the age of 50 with chronic symptoms (>5 years) and cancer risk factors, such as a history of tobacco use or a family history of cancer.

Young et al. review the evidence regarding the treatment of GERD. They discuss how patients with concerning symptoms or those who are failing symptomatic treatment should undergo upper endoscopy. They recommend treatment with a proton pump inhibitor in patients without alarm symptoms.

Incorrect Answers:
Answer A: A barium swallow would be indicated in a patient who presented with symptoms of esophageal dysphagia. Possible etiologies would include Zenker diverticulum or achalasia. This patient denied any difficulty swallowing or feeling of food being stuck in the throat.

Answer B: Colonoscopy could be considered in this patient if his upper endoscopy is unrevealing, as weight loss and melena could be explained by colorectal cancer. In light of this patient’s GERD, upper endoscopy should be performed first.

Answer C: Helicobacter pylori testing can be useful in the workup of gastric and duodenal ulcers but is not usually performed in the evaluation of GERD. Weight loss and melena raise concerns for carcinoma. Treatment of patients with H. pylori includes a proton pump inhibitor, clarithromycin, and metronidazole.

Answer D: A trial of lansoprazole would not be appropriate for this patient presenting with several worrisome symptoms including melena and weight loss. If the patient had presented with typical GERD without these symptoms, a trial of a PPI would be indicated. Cancer should be ruled out first prior to symptomatic treatment.

Bullet Summary:
Patients with gastroesophageal reflux disease who present with alarm symptoms of weight loss, dysphagia, odynophagia, vomiting, gastrointestinal bleeding, or melena should be evaluated with upper endoscopy.


Question: A 27-year-old G1P0000 woman presents to her obstetrician’s office at 24 weeks gestation complaining of new hair growth on her upper lip. She now needs to shave her face every day or else thick hair appears. She also has worsening acne that started several weeks ago. Her pregnancy thus far has been complicated by gestational diabetes, which is managed by diet and exercise. She has a male fetus based on her 20 week anatomy ultrasound. The patient has a medical history of polycystic ovary syndrome. The patient’s temperature is 98.5°F (36.9°C), blood pressure is 121/76 mmHg, pulse is 70/min, and respirations are 13/min. The cardiopulmonary exam is normal, and the patient’s abdomen has a fundal height of 31 cm. A pelvic exam reveals an unremarkable closed cervix and a right-sided adnexal mass without tenderness. Transvaginal ultrasound is performed and shown in Figure A. Which of the following is the most appropriate next step in management?

Answer: Reassurance

Explanation:
This patient presents with hirsutism and acne, symptoms of hyperandrogenism, as well as a solid pelvic mass on ultrasound, most consistent with a luteoma. The most appropriate next step in management is reassurance as the mass tends to self-resolve after pregnancy.

Luteomas are ovarian tumors that arise during pregnancy and produce androgens, causing maternal and sometimes fetal virilization. They appear as solid masses on ultrasound and are not malignant. The likelihood of virilizing the fetus increases if the luteoma arises in the 1st trimester and affected female fetuses present with clitoromegaly or labioscrotal fusion. Male fetuses are not affected. Treatment is supportive as the masses tend to resolve after pregnancy.

Wang et al. review the evidence regarding the diagnosis and treatment of luteomas. They discuss how this is a rare tumor that primarily affects women who have had multiple pregnancies. They recommend early diagnosis of this condition in order to inform treatment options.

Figure/Illustration A shows a transvaginal ultrasound with a solid mass on the right ovary (red circle). This appearance is consistent with a luteoma.

Incorrect Answers:
Answer A: Laparoscopy to prevent detrimental effects on the fetus is not considered a treatment option for luteomas. In this patient, the exposure to high androgen levels is late in pregnancy and the fetus is a male, making it especially unnecessary to perform surgery.

Answer B: Laparoscopy to remove a malignancy is not indicated for luteomas, which are benign tumors and self-regress after delivery. Malignancies that can cause virilization in or outside of pregnancy include Sertoli-Leydig cell tumors and Krukenberg tumors.

Answer C: Percutaneous umbilical blood sampling to determine prognosis may be performed in women who have early virilization and female fetuses. High androgen levels in the umbilical cord are required for the virilization of the fetus, whereas high androgen levels in the mother’s peripheral blood may not predict this outcome.

Answer E: Spironolactone to treat hirsutism and acne is used outside of pregnancy in women with polycystic ovary syndrome. However, because it is an anti-androgen, spironolactone should not be used in pregnancy as it can cause feminization of male fetuses.

Bullet Summary:
Luteomas generally do not require treatment as they regress after pregnancy.


Question: A 5-year-old girl presents to the emergency room due to difficulty walking. She has been complaining of pain in her right leg for the last few days. Her neighbor’s cat bit her last week and her parents attributed the pain to her healing bite. At the time of the bite, they cleaned the wound and irrigated it with sterile saline water from a first aid kit. She has no medical history and has never been hospitalized. Her temperature is 102.2°F (39°C), blood pressure is 118/78 mmHg, pulse is 90/min, respirations are 21/min, and pulse oximetry is 99% on room air. The open wound remains present on the thigh with surrounding erythema and edema. MRI is consistent with osteomyelitis. Which of the following is the most appropriate next step in management?

Answer: Ampicillin and sulbactam

Explanation:
This young girl with a recent history of a cat bite and difficulty walking most likely has likely Pasteurella multocida osteomyelitis. Empiric IV antibiotic therapy with ampicillin-sulbactam is the most appropriate initial management.

Pasteurella multocida is a gram-negative rod that is associated with cat and dog bites. Infection can lead to cellulitis and osteomyelitis. Treatment of minor infection is with amoxicillin-clavulanate; however, patients suspected of having osteomyelitis should be treated empirically with IV antibiotics (e.g., ampicillin and sulbactam) and taken for biopsy/culture to identify the pathogen. Antibiotics can then be narrowed down accordingly. Patients will often require between 4-8 weeks of antibiotic treatment. MRSA coverage may initially be started and tapered later once cultures result.

Mollitt reviews the evidence regarding the microbiology of various injuries. He discusses how Pasteurella multocida is a common complication of animal bites. He recommends early effective antibiotic treatment.

Incorrect Answer:
Answer A: Amoxicillin and clavulanate can be used to treat Pasteurella infection. Patients with osteomyelitis should not be treated with oral antibiotics initially, in particular, when there are systemic manifestations as is present in this patient. IV antibiotics such as ampicillin and sulbactam are the mainstay for empiric osteomyelitis treatment after an animal bite in a patient with systemic manifestations.

Answer C: Doxycycline is used to treat uncomplicated chlamydia infections. Gonococcal osteomyelitis may present in sexually active individuals and may be associated with septic arthritis. Sexually active patients may be suspected of having this disease.

Answer D: Fluconazole is an antifungal that is used to treat Candida osteomyelitis. Candida osteomyelitis would be highly unusual in patients with no other risk factors. Instead, this disease is more common in immunodeficient patients or those who use IV drugs.

Answer E: Vancomycin is used for MRSA infections. Although S. aureus is the most common overall cause of osteomyelitis, this patient with a recent animal bite most likely has Pasteurella infection and this organism should be covered accordingly.

Bullet Summary:
Patients with suspicion of Pasteurella osteomyelitis infection after an animal bite should be treated with empiric IV antibiotics such as ampicillin and sulbactam.


Question: A newborn boy is assessed in the newborn nursery due to central cyanosis that does not respond to oxygen therapy. The patient was born to a G1P1 mother at 39 weeks gestation. The mother had diabetes that was managed with exercise and insulin during the pregnancy. The mother has never been vaccinated and did not follow routine prenatal care. The newborn's temperature is 99.5°F (37.5°C), blood pressure is 70/30 mmHg, pulse is 160/min, respirations are 27/min, and oxygen saturation is 80% on room air. The initial workup of the patient includes a chest radiograph seen in Figure A as well as lab values as seen below. Hemoglobin: 14 g/dL Hematocrit: 42% Leukocyte count: 6,500/mm^3 with normal differential Platelet count: 197,000/mm^3 Serum: Na+: 139 mEq/L Cl-: 101 mEq/L K+: 4.3 mEq/L HCO3-: 24 mEq/L BUN: 12 mg/dL Glucose: 99 mg/dL Creatinine: 0.5 mg/dL Ca2+: 10.0 mg/dL AST: 12 U/L ALT: 10 U/L An electrocardiogram is obtained as seen in Figure B. Which of the following is the most likely diagnosis?

Answer: Transposition of the great vessels

Explanation:
This patient is presenting with right axis deviation on ECG and an "egg on a string" heart on chest radiograph suggesting a diagnosis of transposition of the great vessels.

Transposition of the great vessels occurs when the spiral septum that divides the truncus arteriosus into the aorta and pulmonary artery fails to spiral and connect the right ventricle to the pulmonary artery and the left ventricle to the aorta. Patients will present with central cyanosis and must have another cardiac defect/shunt in order to remain viable (such as an atrial septal defect, ventricular septal defect, or patent ductus arteriosus). Chest radiograph will reveal an "egg on a string" heart and ECG will reveal right axis deviation. The diagnosis is confirmed with echocardiography and treated surgically.

Cohen et al. review the treatment of patients with transposition of the great vessels. They discuss how multiple surgical procedures have been performed in an attempt to address this congenital abnormality. They recommend using MRI to characterize the success of these procedures.

Figure A is a chest radiograph demonstrating an elongated cardiac shadow (red circle). This classic "egg on a string" appearance of the heart is seen in transposition of the great vessels.

Figure B is an ECG demonstrating right axis deviation as revealed by being down in lead I (red circle) and up in aVF. Right axis deviation is classically seen in transposition of the great vessels.

Incorrect Answers:
Answer A: Tetralogy of Fallot presents with a boot-shaped heart on a chest radiograph and classic "Tet spells" where patients will squat thus improving shunting and cardiac performance. Treatment is with surgical correction of the abnormal spiral septum.

Answer B: Total anomalous pulmonary venous return occurs when pulmonary veins drain into the right heart circulation. It presents with cyanosis that does not correct with oxygenation but does not present with an "egg on a string" heart on a chest radiograph. Treatment is with surgical reconfiguration of pulmonary venous return.

Answer D: Tricuspid valve atresia occurs when the tricuspid valve never forms and thus there is no connection between the right atrium and right ventricle. Patients will present with cyanosis and poor feeding/poor growth. Treatment is with surgical creation of a connection between these chambers.

Answer E: Truncus arteriosus occurs secondary to failure of the spiral septum to divide the aorta and pulmonary artery. It presents with poor feeding, diaphoresis, tachypnea, and cyanosis. Treatment is with surgical separation of these arterial chambers.

Bullet Summary:
Transposition of the great vessels presents with central cyanosis, an "egg on a string" appearance on a chest radiograph, and right axis deviation on ECG.


Question: A 2-year-old boy is brought to the emergency room by his mother, who states that her son has been coughing uncontrollably for 3 hours. The child has a medical history of obesity and atopic dermatitis and uses topical steroid cream. His birth history is unremarkable. His family history is notable for asthma in his older sister and irritable bowel syndrome in his father. His temperature is 98.5°F (36.9°C), pulse is 120/min, blood pressure is 90/52 mmHg, and respirations are 32/min. On exam, he appears uncomfortable, is coughing continuously, and is drooling. Cardiopulmonary and abdominal exams are unremarkable. A chest radiograph is performed and the results are shown in Figures A and B. Which of the following is the most appropriate next step in management?

Answer: Endoscopic removal

Explanation:
This child presents with foreign body ingestion with a button battery seen in the esophagus on radiography. The most appropriate next step in management is urgent endoscopic removal of the battery.

Button batteries are commonly used in watches and small electronic devices. If these objects are ingested (usually by children), they can become lodged in the esophagus. Coughing, drooling, and chest discomfort are classic symptoms but a lack of symptoms does not negate the need for evaluation if suspicion is high. The location of the battery can be confirmed by radiograph and orthogonal views can localize the object in the esophagus versus the trachea. Endoscopy is the preferred method of removal as direct visualization of any associated esophageal injury is possible. The battery can cause ulceration or perforation if left in the esophagus due to chemical extravasation.

Baharudin et al. review a number of cases of pediatric ingestions resulting in esophageal lodging. They discuss how a stack of coins can mimic the appearance of a battery. They recommend urgent intervention in cases of suspected battery ingestion.

Figure/Illustration A is a chest radiograph depicting a round object lodged in the esophagus, with a “double halo” sign (red circle). This sign is an indication that this object is a battery rather than a coin. Figure/Illustration B is a lateral chest radiograph demonstrating that the battery is posterior to the trachea (red circle). This view confirms that the location of the battery is in the esophagus.

Incorrect Answers:
Answer A: Balloon catheter removal can be attempted for ingested button batteries but is typically used only if endoscopy is not available. There is more potential for tissue damage without direct visualization, so ingestion time greater than 2 hours is generally a contraindication for this method.

Answer B: Ipecac administration can induce emesis and is rarely used for toxic ingestions. Vomiting can cause further lodging in the esophagus and even more tissue damage. Ipecac is therefore not recommended in the modern management of toxic ingestions.

Answer D: Observation would be appropriate if there is an ingested object that has already traveled further into the gastrointestinal tract (if they are small and smooth), as these objects would likely pass on their own. A classic example would be a coin ingestion that would appear as a single round object rather than a double ring appearance. A button battery in the esophagus is an emergency and should be removed urgently.

Answer E: Surgical extraction of a battery with associated repair may be required if there is suspicion of an esophageal-vascular fistula, mediastinitis, or other such complications. It may also be necessary if a magnet was simultaneously ingested. In the absence of these complications, endoscopic removal should be attempted first.

Bullet Summary:
Button batteries lodged in the esophagus require urgent endoscopic removal.


Question: A 44-year-old homeless man presents to the emergency department after being stabbed multiple times in the abdomen. The patient is intoxicated and is unable to offer further history. His temperature is 97.5°F (36.4°C), blood pressure is 92/52 mmHg, pulse is 145/min, respirations are 33/min, and oxygen saturation is 90% on room air. He is intubated to protect his airway, given 2 units of packed red blood cells, and sent to the operating room for an exploratory laparotomy. The patient is subsequently admitted to the intensive care unit. He is extubated the next day and appears well. His vitals are within normal limits. Physical exam reveals sparse hair that is falling out throughout the patient’s body. He has a rash by the corners of his mouth. The patient has multiple loose bowel movements and on day 6 the patient’s surgical wound does not appear to be healing. It is held together only by the sutures with minimal underlying healing. Which of the following is most likely deficient in this patient?

Answer: Zinc

Explanation:
This homeless patient who likely has poor nutritional status presents with angular cheilitis, sparse hair that is falling out, diarrhea, and poor wound healing, all of which are suggestive of zinc deficiency.

Zinc is involved in many physiologic processes and is an important mineral to include in the diet. Zinc deficiency is common in patients with poor nutritional status such as the homeless, individuals living in developing nations without access to food, and patients with eating disorders. Many malabsorptive conditions can cause zinc deficiency including steatorrhea and chronic pancreatitis. Zinc deficiency presents with impaired wound healing and impaired immune function. Other symptoms suggestive of zinc deficiency include xerosis, alopecia, stomatitis, oral ulceration, angular cheilitis, impaired vision (night blindness), impaired smell/taste, diarrhea, and anorexia. The treatment of zinc deficiency involves zinc supplementation and workup for any other nutritional deficiencies.

Nagata etc al. study the incidence of zinc deficiency among younger patients with anorexia nervosa. The authors find that men and women are both equally likely to have zinc deficiency when admitted. The authors recommend screening all patients with eating disorders for zinc deficiency.

Incorrect Answers:
Answer A: Riboflavin deficiency may present with angular cheilitis, stomatitis, and a non-specific rash. The treatment involves supplementing or consuming foods with riboflavin; however, it is rare in the developed world to be riboflavin deficient (due to fortified foods) and would not cause such significant wound healing issues as in this patient.

Answer B: Thiamine deficiency is common in alcoholics and can cause Wernicke-Korsakoff syndrome, which presents with ataxia, nystagmus, and ophthalmoplegia in addition to amnesia. The treatment involves the administration of high-dose thiamine.

Answer C: Vitamin C deficiency causes scurvy, which presents with easy fractures, bleeding gums or loose teeth, delayed wound healing, and perifollicular hemorrhages. It is common in the homeless and alcoholics. Treatment involves vitamin C replacement or a diet rich in fruits and vegetables.

Answer D: Vitamin D deficiency is common in the homeless, alcoholics, or those who suffer from steatorrhea (such as chronic pancreatitis or Crohn disease). It presents with weak, soft bones (osteomalacia/osteoporosis), and hypocalcemia which may present with paresthesias and tetany. Treatment involves replacement of vitamin D.

Bullet Summary:
Zinc deficiency presents with poor wound healing, hair loss, infertility, diarrhea, anorexia, and impaired immune function.