A challenging case of mast cell sarcoma primarily involving the bone marrow
A 63-year-old man presented with fever, splenomegaly, hyperferritinemia (10 798 ng/dL), elevated soluble interleukin-2R (6644 pg/mL), anemia (hemoglobin 6.9 g/dL), and thrombocytopenia (42 000/μL). Atypical cells were seen on the blood smear (panel A; Wright-Giemsa stain, 50× objective). Bone marrow aspirate showed large pleomorphic tumor cells with metachromatic granules and hemophagocytosis (panel B; Wright-Giemsa stain, 40× objective). Bone marrow biopsy showed a destructive growth pattern (panel C;