Secondary malignant fibrous histiocytoma following refractory langerhans cell histiocytosis.

We describe a rare case of secondary malignant fibrous histiocytoma (MFH) following Langerhans cell histiocytosis (LCH). A 23-year-old Japanese male exhibited systemic lymphadenopathy, multiple lung tumors, and osteolytic changes in bilateral iliac bones in 1989. A biopsy specimen from the left iliac bone revealed an infiltration of S-100 protein-positive histiocyte-like cells intermingled with eosinophils, which confirmed the diagnosis of eosinophilic granuloma, a type of LCH.