Carcinosarcoma of the esophagus with metastases showing osteosarcoma: a case report and review of the literature.

Carcinosarcoma of the esophagus includes both carcinomatous and sarcomatous elements. The classification and histogenesis of carcinosarcoma is controversial. In a polypoid carcinosarcoma diagnosed in a resected esophagus the sarcomatous component was composed of dense interlacing bundles of spindle-shaped cells in the submucosa. Areas with transitional features between the two components were observed. Immuno-histochemical examination showed vimentin-positive cells in the sarcomatous areas. Subsequently, obtained autopsy specimens from the lung, kidney and iliac bone showed metastatic osteosarcoma composed of an interlacing pattern of bone or osteoid components. We suspected that the sarcomatous elements in the esophagus resulted from sarcomatous transformation of carcinoma cells, and that the metastatic lesions showed differentiation of neoplastic cells to the osteosarcoma.