Primary Extragonadal Retroperitoneal Pure Yolk Sac Tumor

Primary germ cell tumors of extragonadal origin are rare and exact incidence of this type cancer is unknown. They have been estimated to represent 3-5% of all adult germ cell malignancies (1). The origin of primary extragonadal germ cell tumors (EGGCT) is still a matter of debate. According to widely accepted theory, during embryogenesis, germ cells are misplaced anywhere at the midline. The mechanism of this misplacement is poorly understood, but malignant transformation of these cells leads to EGGCT at these regions (2-3). The most common sites of origin are, in decreasing order of frequency, the mediastineum, retroperitoneum, sacrococcygeal region and pineal gland, although many unusual sources have been reported (4). We report a case of primary extragonadal retroperitoneal pure Yolk sac tumor (YST) which could not be totally removed during operation and clinical remission was obtained after 4 courses of BEP chemotherapy. PRIMARY EXTRAGONADAL RETROPERITONEAL PURE YOLK SAC TUMOR