Microscopic examination revealed a dense dermal infiltrate consisting of moderately sized atypical monocytoid cells exhibiting pleomorphism, necrosis, and mitotic figures, features characteristic of leukemia cutis. The white blood cell count was higher than 90 × 109/L (reference range, 5.0-10.0 × 109/L). A peripheral blood smear obtained at the time of presentation (Figure 4) contained numerous blast cells. A bone marrow biopsy specimen demonstrated well-differentiated promonocytes and monocytes as the predominant white cells. Flow cytometric studies revealed CD13, CD14, and CD33 positivity, suggesting a myeloid/monocytic lineage. Histochemical analysis demonstrated strong positive staining for α-naphthyl acetate esterase. Based on the results of these studies, the patient was diagnosed as having acute myelogenous leukemia, class M5b.
Diffuse and Progressive Papules and Nodules. Arch Dermatol. 2000;136(6):791-796. doi: