Systemic Mast-Cell Disease (Mastocytosis)

Figure 1. A 71-year-old man presented with hepatosplenomegaly and multiple macular, hyperpigmented, nonpruritic skin lesions on the trunk, legs, and arms (Panel A). The hemoglobin level was 9.1 g per deciliter, the platelet count was 112,000 per cubic millimeter, and the white-cell count was 36,200 per cubic millimeter, with monocytosis, lymphopenia, 16 percent myelocytes, and 3 percent blasts. A bone marrow biopsy revealed findings consistent with the presence of chronic myelomonocytic leukemia, fibrosis, osteosclerosis, and increased numbers of mastocytes, but not of blasts. There were numerous mastocytes, including spindle-cell forms (arrow in Panel B; Giemsa stain, ×40), and multiple extracellular . . .