Malignant intrathoracic oncocytoma.

A case of malignant intrathoracic oncocytoma occurring in a 56-year-old man is reported. Preoperative films of the chest showed a large superior mediastinal tumor. Radical excision through a right-sided thoracotomy was impossible because of the extensive growth. Light and electron microscopic findings revealed a malignant oncocytoma with metastases in lymphoid tissue and tumor emboli in lymph vessels. Postoperative treatment with cyclophosphamide was recommended for one year. After two years there was no radiologic or scintigraphic evidence of metastases. Review of the literature on malignant oncocytoma suggests a relatively benign course after surgical excision. The role of radiotherapy and chemotherapy cannot yet be established.