Atypical generalized eruptive histiocytosis associated with acute monocytic leukemia.

Histiocytoses are diseases caused by proliferation of either dendritic cells/Langerhans cells or of monocytes/macrophages. Generalized eruptive histiocytosis belongs to the cutaneous non-Langerhans cell histiocytoses and is a rare monocyte-macrophage proliferative disorder that usually follows a benign clinical course. We present the case of a 59-year-old man who presented with a 7-month history of progressively developing erythematous macules and slightly elevated papules widely distributed over the trunk, neck, face, and thighs.