PMC7725938_01
Bone marrow biopsy showing marrow cavity diffusely infiltrated by a compact sheet-like proliferation of neoplastic mast cells (Low magnification, X200).
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The bone marrow examination demonstrated a diffuse infiltration of the marrow cavity by a compact proliferation of abnormal mast cells occupying >70% of the intertrabecular marrow space (Fig. 1a, b). The mast cells, which accounted for at least 40% of the bone marrow aspirate smear differential count, included mostly promastocytes with a majority of the cells displaying classical nuclear bilobation and a round cytoplasm (Fig. 1c) with some spindle shaped immature forms also noted (Fig. 1d).
Bone marrow biopsy showing marrow cavity diffusely infiltrated by a compact sheet-like proliferation of neoplastic mast cells. (High magnification, x400).
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Immunochemistry demonstrated a strong expression of CD 117 (KIT), Tryptase, CD25, and CD2 (Fig. 2a-d).
Bone marrow aspirate smear showing promastocytes (immature cells with bilobated nuclei and cytoplasms packed with metachromatic mast cell granules).
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Autopsy demonstrated splenomegaly with a spleen weight of 1570 gm (normal: 150-200 gm) displaying a diffuse infiltration of mast cells (Fig. 3), and hepatomegaly with a liver weight of 3100 gm (normal: 1200-2000 gm) also showing diffuse infiltration of mast cells (Fig. 4).