An 18-month-old boy, whose parents are first cousins, is referred to you because of a significant episode of epistaxis. The parents report that the child had bleeding after circumcision and large hematomas with immunizations. Platelet aggregation studies show the following: This child's platelets are unable to interact with which of the following?

Correct Answer: B

Rationale: The correct answer is B: Fibrinogen. In this scenario, the child likely has Glanzmann thrombasthenia, a rare inherited platelet disorder where platelets lack functional integrin αIIbβ3, preventing binding to fibrinogen. This results in impaired platelet aggregation and clot formation, leading to bleeding issues. Choices A, C, and D are incorrect because platelet aggregation studies would typically show normal interactions with ADP, von Willebrand factor, and Platelet factor 4 in Glanzmann thrombasthenia.

Correct Answer: D

Rationale: The correct answer is D: Add gabapentin three times daily. Gabapentin is a first-line option for neuropathic pain, which is likely the cause of the patient's burning, tingling, and shooting leg pain. The worsening of pain with hot showers is also characteristic of neuropathic pain. Gabapentin's mechanism of action in reducing neuropathic pain makes it a suitable choice for this patient. Switching to methadone (A) may not directly address the neuropathic pain component. Recommending more frequent use of immediate release oxycodone (B) may lead to increased risk of opioid-related adverse effects. While amitriptyline (C) is also used for neuropathic pain, starting with gabapentin is more appropriate given the patient's current opioid regimen and EKG findings.

Correct Answer: A

Rationale: The correct answer is A: Abnormal lysosomal biogenesis. The patient's presentation of silvery hair and hypopigmented skin suggests a lysosomal storage disorder like Chediak-Higashi syndrome. The peripheral smear showing 10% neutrophils with a low leukocyte count indicates impaired neutrophil function due to abnormal lysosomal biogenesis. This affects phagocytosis and intracellular killing of pathogens, leading to recurrent infections and abscess formation. Incorrect choices: B: Abnormal ribosome function - not related to the patient's presentation. C: Abnormal phagocytosis of opsonized particles - the primary issue is with lysosomal biogenesis, not phagocytosis. D: Abnormal mitochondrial activity - does not explain the silvery hair and hypopigmented skin seen in Chediak-Higashi syndrome.

Correct Answer: A

Rationale: Step 1: Semen analysis is the gold standard for assessing male fertility. Step 2: The patient's history of ALL and completion of therapy make semen analysis relevant. Step 3: Long-term survivors of ALL are at risk for infertility due to treatment effects. Step 4: Semen analysis can provide valuable information on sperm count, motility, and morphology. Summary: - Option A is correct as semen analysis is crucial for assessing male fertility. - Option B is incorrect as alkylator dosages affect both males and females. - Option C is incorrect as sperm cryopreservation should ideally be offered at diagnosis. - Option D is incorrect as infertility risk may be higher than testosterone deficiency in this case.

Correct Answer: C

Rationale: The correct relationship between mean, median, and mode in a highly right-skewed distribution is that the mean is greater than the median and mode. In a right-skewed distribution, the mean is pulled towards the longer tail, making it greater than the median, which is the middle value when the data is arranged in order. The mode is the most frequent value, but in a right-skewed distribution, it will be the smallest value, making the mean greater than both the median and mode. Therefore, choice C is correct. Choices A, B, and D are incorrect because they do not reflect the specific relationship between mean, median, and mode in a highly right-skewed distribution.