Hematologic Malignancies USMLE Step 1 Practice Question
A 58-year-old man presents to the emergency department with abdominal pain, jaundice, and early satiety. He has a history of hepatitis C cirrhosis complicated by portal hypertension. Vital signs: BP 128/76, HR 92, RR 18, temperature 37.2°C, SpO2 98% on room air. Physical examination reveals hepatomegaly with a firm, nontender liver edge, but the spleen is not palpable. Laboratory values include WBC 45,000/μL with left shift (12% myeloblasts, 18% metamyelocytes), hemoglobin 9.2 g/dL, and platelets 120,000/μL. Abdominal ultrasound with Doppler shows a large heterogeneous 8 cm hepatic mass with increased vascularity and patent portal vein. Bone marrow aspiration and biopsy demonstrate normal cellularity with only 8% blasts and no evidence of fibrosis. Flow cytometry of peripheral blood confirms myeloid blasts. Which of the following best explains the discrepancy between the peripheral blood blast percentage and bone marrow blast percentage?
Answer choices
- AExtramedullary hematopoiesis with leukostasis from a hepatic myeloid sarcoma (chloroma)Correct answer
- BChronic myeloid leukemia in blast crisis with hepatic involvement
- CAcute leukemic transformation of underlying myelodysplastic syndrome
- DLeukemoid reaction secondary to acute hepatic necrosis and infection
- ESplenic sequestration of normal mature myeloid precursors causing relative blast predominance
- FHepatocellular carcinoma producing granulocyte colony-stimulating factor (G-CSF)
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