Malignant mediastinal myxoid tumor and renal cell carcinoma.

A 69-year-old man with a malignant mediastinal myxoid tumor and a right renal cell carcinoma died from bilateral compression atelectasis after a two months' clinical course. The mediastinal tumor simulated a myxoid malignant fibrous histiocytoma (MFH) because of great pleomorphism of tumor cells, although the histological differential diagnosis of myxoid MFH, other myxoid sarcomas, and metastatic renal cell carcinoma was very difficult. Three reported cases of primary mediastinal MFH are briefly reviewed.