A mediastinal germ cell tumor of yolk sac type--case report.

OBJECTIVE: We report an extremely rare case of germ-cell tumor localized at the level of the anterior mediastinum.

CLINICAL PRESENTATION: A 36-year-old man who presented with left subclavial vein thrombosis was admitted to our hospital for specific cure. Computed tomographic scan of the chest showed a large anterior mediastinal mass. Surgical intervention revealed an infiltrative mediastinal tumor involving the left subclavial vein, which was biopsied for morphological examination. Histologically, the tumoral mass proved to be a carcinoma, with papillary and tubular growth patterns. Immunohistochemical stains for alpha-fetoprotein were positive in the tumor cells while stains for carcinoembryonic antigen and placental like alkaline phosphatase were negative. The serum level of alpha-fetoprotein of this patient was elevated, as well. This supported the diagnosis of Yolk sac tumor, a rare primary tumor within the mediastinum. Postsurgery, the patient received a combination chemotherapy consisting of cisplatin, vepesid and bleomycin every 3 weeks for a total of 4 cycles. During the treatment, the alpha-fetoprotein level, was decreasing.

CONCLUSION: Primary mediastinal Yolk sac neoplasm is a rare tumor. The diagnosis should be made not only by morphological studies but also the patient's age and the elevation of serum alpha-fetoprotein. In spite of modern chemotherapy, the prognosis of mediastinal yolk sac tumor remains poor. The single most important prognostic indicator is whether the tumor mass can be completely excised before or after chemotherapy.