Immature myeloid precursors in chronic neutrophilic dermatosis associated with myelodysplastic syndrome.

Sweet syndrome (SS) associated with myeloproliferative disorders has been considered an inflammatory process mediated by neutrophils in which immunologic mechanisms are operative. The authors report the case of a 68-year-old man suffering from a myelodysplastic syndrome, who presented with a relapsing skin eruption resembling SS. Histopathologically, the skin infiltrates showed prominent neutrophilic features masking the underlying malignant process. Extensive immunophenotypic studies of skin revealed the presence of a few immature myeloid cells intermingled with an overwhelming infiltrate of neutrophils. The atypical cells in the skin had a phenotype identical to that of leukemic cells in the peripheral blood and bone marrow. Whether or not immature myeloid cell precursors constitute a specific infiltrate of leukemia cutis or are a result of recruitment of circulating leukemic cells to this area of inflammation is discussed.