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. Although the patient was treated with prednisolone initially, the disease did not respond well and progressed gradually over time. The patient subsequently received multiple courses of chemotherapy and immunosuppressive therapy with many kinds of anticancer agents for 6 years. He also received radiotherapy totaling 136.8 Gy for lung tumors and osteolytic lesions of the pelvis. In 1997, because of the LCH refractoriness, biopsy was performed again from the right inguinal lymph node. Microscopic examinations demonstrated a mixture of spindle-shaped cells and histiocyte-like cells, which appeared to be in a storiform pattern. The tumor cells were immunohistologically positive for CD68 and vimentin, but negative for CD1a and S-100 protein. Therefore, the patient was diagnosed with MFH. Although chemotherapy was continued, the patient died of pneumonia during the neutropenic period following chemotherapy. Autopsy revealed systemic invasion of MFH and dissemination of mucormycosis. LCH was not detected histologically in any tissues.