Malignant fibrous histiocytoma of the esophagus.

A 78-year-old man presented with an esophageal polyp that was confirmed by immunohistochemistry and electron microscopy to be malignant fibrous histiocytoma. The tumor was comprised of a proliferation of spindle-shaped cells admixed with bizarre giant cells. These tumor cells were immunoreactive for smooth muscle actin, vimentin, alpha-1-anti-chymotrypsin and CD68. Electron microscopic examination revealed the myofibroblastic and histiocytic features of the tumor cells. No elements of epithelial or myogenic differentiation were found in the tumor. Malignant fibrous histiocytoma of the esophagus is extremely rare, with 10 cases being documented so far in the literature. The differential diagnosis of pleomorphic tumors of the esophagus is discussed.