Fine needle aspiration of mediastinal germ cell tumors.

Germ cell tumors in the mediastinum are rare and often occur in young patients but may occur in older patients. Seminoma, embryonal carcinoma, yolk sac tumor, choriocarcinoma and teratoma have distinct morphologic features with high grade nuclei. They are the primary diagnostic consideration in young males but may be lower on the list in older patients, where they may be misdiagnosed as carcinomas. Review of the history, use of immunohistochemistry stains and recognition of morphologic features will help to make the diagnosis of germ cell tumor of the mediastinum. These tumors have a good to intermediate prognosis, depending on when they are detected.