Malignant granular cell tumor. Report of a case with special reference to carcinoembryonic antigen.

A case of malignant granular cell tumor and its histochemical and electron-microscopic characteristics are reported. This case showed, in addition to the well-known distribution of this type of tumor in subcutaneous fat, mediastinum, retroperitoneum and lungs, multiple foci in the myocardium. Contrary to recent studies reporting the presence of carcinoembryonic antigen (CEA) in benign and malignant granular cell tumors, this case is CEA-negative. We suggest that the reported CEA-reactivity in this type of tumor is probably due to cross-reacting antibodies against antigens, presumably associated with lysosomes.