A 9-month-old boy has been referred to you for the evaluation of an enlarged abdomen. Imaging studies show a large liver mass (PRETEXT III). Alfa-fetoprotein is 98 ng/mL, and a CT scan of the lungs show bilateral lung metastases. A needle biopsy is performed, and you are planning to review the specimen with the pathologist. Which of the following diagnoses are you suspecting?

Correct Answer: D

Rationale: The correct answer is D: Small cell undifferentiated hepatoblastoma. In hepatoblastoma, the presence of lung metastases indicates a high-risk tumor. The small cell undifferentiated subtype is more aggressive with a poorer prognosis compared to other subtypes. The AFP level is lower than typically seen in hepatoblastoma, but still within the range for this diagnosis. Pure fetal histology hepatoblastoma (choice A) is less common and usually associated with a better prognosis. Embryonal sarcoma of the liver (choice B) is a distinct entity with different histological features. Fibrolamellar hepatocellular carcinoma (choice C) typically occurs in older children and has a different imaging appearance.

Correct Answer: B

Rationale: The correct answer is B: Administer L-asparaginase immediately after the methotrexate infusion. This is the most appropriate sequence because methotrexate can impair the activity of L-asparaginase if administered together. By waiting to administer L-asparaginase after the methotrexate infusion, the efficacy of both drugs is maximized without interference. Administering L-asparaginase during the methotrexate infusion (Choice A) would lead to decreased effectiveness of L-asparaginase. Administering both drugs at the same time (Choice C) is not recommended due to potential drug interactions. Administering methotrexate 24 hours after the asparaginase (Choice D) does not optimize the synergistic effects of the drugs during interim maintenance chemotherapy.

Correct Answer: D

Rationale: Thrombomodulin alters thrombin's function by binding to it and activating protein C. Activated protein C then inhibits factors Va and VIIIa, which are essential for the formation of fibrinogen. Protein C (choice A) also inhibits coagulation, but it doesn't directly alter thrombin's function. Protein S (choice B) enhances protein C's activity but doesn't directly affect thrombin. Antithrombin (choice C) inhibits thrombin and other coagulation factors, but it doesn't specifically alter thrombin's function to downregulate fibrinogen formation.

Correct Answer: B

Rationale: Step-by-step rationale for why answer B is correct: 1. Autoimmune thrombocytopenia is a condition where the body's immune system attacks and destroys its own platelets. 2. Platelet transfusions in patients with autoimmune thrombocytopenia are less likely to be successful due to the underlying immune response. 3. Reviewing transfusion records of subjects with this condition would likely show a pattern of unsuccessful platelet transfusions. 4. This conclusion is supported by medical knowledge and understanding of autoimmune thrombocytopenia. Summary: - Choice A is incorrect because frozen storage of platelets does not necessarily increase units available in the context of the study. - Choice C is incorrect as platelet units can carry a risk of transmission for hepatitis C infection. - Choice D is incorrect as the preference for pooled donor platelets over single-donor platelets is not a conclusion that can be drawn from the study.

Correct Answer: D

Rationale: Ferroportin is a transmembrane iron exporter responsible for releasing iron from cells into the bloodstream. It is crucial in regulating systemic iron levels. Choice A is incorrect as storage iron is typically stored as ferritin. Choice B is incorrect as ferroportin is not found in the plasma but on cell membranes. Choice C is incorrect as erythroid progenitors do not directly interact with ferroportin. Therefore, the correct answer is D as it accurately describes the function of ferroportin in iron metabolism.