KIT D816V Positive Acute Mast Cell Leukemia Associated with Normal Karyotype Acute Myeloid Leukemia

Figure 1

Peripheral blood smears showing different types of morphologically abnormal mast cells. Leishman’s stain (a, 40x; b, 100x). Circulating mast cells (MC) had variable morphological features, from metachromatic blasts of medium to large cell size, round to oval shape, fine/immature nuclear chromatin, high nuclear : cytoplasmic ratio, and cytoplasmic metachromatic granules, to atypical MC type 2 with variable, sometimes spindle, cell shape, bilobated nucleus with fine to moderately condensed chromatin, variable nuclear : cytoplasmic ratio, and hypogranulated cytoplasm. Please note that in spite of these heterogeneous morphological features, all the MC present in the peripheral blood had an aberrant immature phenotype, corresponding to abnormal MC precursors (Figure 4).