Solitary Langerhans cell histiocytoma

Biopsy of a solitary tumor of the buttock in a 3-month-old girl was diagnosed as a histiocytic proliferation suggestive of histiocytosis X. Electron microscopy showed Birbeck granules and dense myelinlike bodies within the cytoplasm of the tumor cells. An immunoperoxidase study, using a panel of monoclonal antibodies (OKT6, OKT4, and OKM1) and a polyclonal anti-S100 protein antibody, showed positive staining for OKT6 and OM1 and moderately positive staining for OKT4 and S100. After surgery to remove the tumor, visceral involvement could not be demonstrated during a 20-month follow-up.