True carcinosarcoma of the esophagus with osteosarcoma

We experienced a case of true carcinosarcoma of the esophagus with osteosarcoma. Computed tomography scan revealed calcification of the tumor. Immunohistochemically, vimentin staining was positive, and osteoid formation was found in the sarcomatous portion. It was clear that the lesion contained osteosarcoma of mesenchymal origin, and thus we diagnosed it as true carcinosarcoma.