"Aleukemic" granulomatous leukemia cutis

Aleukemic leukemia cutis is a rare condition characterized by the infiltration of the skin by leukemic cells before their appearance in the peripheral blood. The authors report a case of aleukemic leukemia cutis in a 30-year-old seemingly healthy man who presented with multiple skin papulonodular lesions and lack of peripheral blood involvement. Histopathologically, the skin infiltrates showed prominent granulomatous features that masked the underlying malignant process. Immunophenotypic studies of skin and bone marrow infiltrates revealed the myelomonocytic lineage of the atypical cells, consistent with M4 acute myelomonocytic leukemia. The authors emphasize the value of immunohistochemical studies in diagnosing a cutaneous atypical infiltrate and discuss problems of histopathologic differential diagnosis.