Endodermal sinus tumor (yolk sac tumor), seminoma and hemangiopericytoma. Rare primary mediastinal tumors. A report on the course of the disease in nine patients.

The pathological and clinical features of primary mediastinal hemangiopericytoma, seminoma, and endodermal sinus tumor are presented and discussed. These tumors were found in 3 patients each out of 898 cases of mediastinal tumor. Primary thoracic hemagiopericytomas are rare. The diagnosis can be determined by histology only, but nothing can be said about the malignancy of the tumor. Tumor recurrence is relatively frequent. Two patients were radically operated, and they are living today 4 and 4 1/2 years later, without evidence of recurrence. The third patient with clinically clearly malignant hemangiopericytoma was inoperable. This patient died 6 months after diagnosis. The anterior mediastinum is a predilection site for extragonadal germ cell tumors. Histologically there is no difference between this tumor and the gonadal seminoma. This tumor is well known to be radiosensitive. All 3 male patients were inoperable and received radiotherapy. One patient died after 4 months, the other 2 are living one and 3 years later, respectively, without complaints or evidence of recurrence. Only 12 cases of primary mediastinal endodermal sinus tumors have been reported in the literature, we observed 3 more such tumors. The highly malignant alpha-fetoprotein producing tumor occurs exclusively in young males. There is, as yet, no clear-cut form of treatment. One of our patients died after 2 weeks, another received chemotherapy and died a few months after diagnosis, the third received chemotherapy and irradiation and is living today, 20 months after discovery of the tumor.