Granulomatous dermatitis with enlarged histiocytes: a characteristic pattern of granulocyte colony-stimulating factor. Report of two cases and review of the literature.

Two patients developed a pruritic maculopapular rash following treatment with granulocyte colony-stimulating factor (G-CSF). Histopathological examination disclosed a superficial dermal inflammatory infiltrate composed of interstitially arranged large histiocytic CD68+ cells and perivascularly disposed lymphocytes. Large histiocytes were interspersed among the collagen bundles with associated slight deposits of mucin. Elastophagocytosis was occasionally observed, and a slight reduction of dermal elastic fibers was also noted. There was no evidence of frank granuloma formation, fibrosis or significant changes of collagen bundles. This histopathological variant of granulomatous dermatitis with "enlarged histiocytes" seems to be characteristic of an unusual cutaneous reaction secondary to CSF treatment.