Primary hepatic mixed germ cell tumor in an adult.

Primary hepatic mixed germ cell tumor (GCT) is very rare, and less than 10 cases have been reported. We report a case of mixed GCT composed of a choriocarcinoma and yolk sac tumor, which occurred in the liver of a 40-year-old woman. A large mass was detected by computed tomography solely in the liver. Serum β-human chorionic gonadotropin (hCG) was highly elevated, otherwise, other serum tumor markers were slightly elevated or within normal limits. For hepatic choriocarcinoma, neoadjuvant chemotherapy was administered, followed by right lobectomy. Histologic features of the resected tumor revealed characteristic choriocarcinoma features with diffuse positivity for hCG in the syncytiotrophoblasts and diffuse positivity for α-fetoprotein and Sal-like protein 4 in the yolk sac tumor components. Primary malignant GCT in the liver is associated with a poor prognosis and requires specific treatment. Therefore, GCT should be considered during a differential diagnosis of a rapidly growing mass in the liver.