The ultrastructure of malignant fibrous histiocytoma (case report).

A soft tissue malignant fibrous histiocytoma was studied by light and electron microscopy. The presence of fibroblast-like cells, histiocyte-like cells, undifferentiated stem cells, and xanthomatous cells was confirmed. Fibroblast- and histiocyte-like multinucleated giant cells were also observed. The observation of lysosomes in some fibroblast-like cells, the features of undifferentiated stem cells, and the presence of cells and intermediate characteristics common to xanthomatous, histiocytic, and stem cells suggest a strict relationship among these cellular types.