Testicular germ cell tumor composed of placental site trophoblastic tumor and teratoma

SummaryWe present a case of a 24-year-old man with a right testicular mass, 2.5 cm in largest diameter. Before orchiectomy, the serum level of β-human chorionic gonadotropin (hCG) was elevated, whereas that of α-fetoprotein was normal. Histologic examination showed a malignant germ cell tumor with a unique and hitherto unpublished combination of placental site trophoblastic tumor and teratoma. Testicular tubules adjacent to the tumor contained intratubular germ cell neoplasia. All cells of placental site trophoblastic tumor were immunohistochemically cytokeratin 7, 18, and pancytokeratin positive and cytokeratin 20, S-100 protein, α-fetoprotein, placental alkaline phosphatase, p63, OCT3/4, Nanog, and calretinin negative. Ten percent of the placental site trophoblastic tumor stained with hCG, 30% with epithelial membrane antigen and human placental lactogen, and 80% with inhibin antibodies. FISH study showed a gain on the short arm of chromosome 12 in the placental site trophoblastic tumor, proving that this component is of germ cell origin. The patient is alive and well 3 years after the orchiectomy without additional treatment.