Malignant fibrous histiocytoma of the tongue: report of a case and ultrastructural observations.

A 42-year-old female presented with a 2.5 cm symptomless swelling on the left lateral surface of the tongue. Histologically, there were large, often pleomorphic, fibroblast-like and histiocyte-like cells, multinucleate giant cells and cells of variable morphology. Many of the cells had abundant vesicular cytoplasm. There were also aggregations of neutrophilic or eosinophilic leukocytes, or both. The cells in some areas formed a fascicular or storiform pattern, or both. Ultrastructurally, the vesicular appearance was due mostly to markedly dilated endoplasmic reticulum, but many of the neoplastic cells contained some lipid. There were some myofibroblasts and a few xanthofibroblasts. The cells of variable morphology had many of the ultrastructural features of the fibroblast and histiocyte-like cells. There were also some small undifferentiated cells with minimal cytoplasm. These ultrastructural features confirmed the histological diagnosis of malignant fibrous histiocytoma.