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Sarcomatoid intracardiac metastasis of a testicular germ cell tumor closely resembling primary cardiac sarcoma.

This report describes a 40-year-old man with a remote history of testicular mixed nonseminomatous germ cell tumor (NSGCT) treated by surgery and chemotherapy. He presented 10 years later with shortness of breath and was found to have a mass occupying the right atrium, based high in the superior vena cava. He also had multiple pulmonary emboli. The sarcomatous and myxomatous histological appearance of the neoplasm closely resembled a primary cardiac sarcoma. However, immunohistochemical studies confirmed the diagnosis of metatstatic sarcomatoid germ cell tumor. Metastatic spindle cell tumors have been reported in patients with NSGCTs. These neoplasms are thought to arise from the spindle cell component of the yolk sac tumor that is resistant to chemotherapy.