Primary yolk sac tumor of the retroperitoneum: A case report and review of the literature.

Yolk sac tumor (YST), also known as an endodermal sinus tumor, is a rare malignant germ cell tumor. Primary retroperitoneal YST (PRYST) is extremely rare and, to the best of our knowledge, has only been described in case reports. The histogenesis of PRYST and the appropriate treatment strategy remain unclear due to the rarity of this type of tumor. The present study reports a case of YST in the retroperitoneum. A 19-year-old female presented with abdominal distension and edema of the lower limbs. A computed tomography scan revealed a large, solid mass located in the retroperitoneum. The tumor size was 20×25×30 cm and widespread metastasis was identified during the exploratory laparotomy. The postoperative histopathology report showed a malignant retroperitoneal tumor (although a YST was initially considered). The patient underwent three surgical procedures and 17 cycles of five different chemotherapy regimens. The patient succumbed to cachexia, which was due to tumor recurrence, and liver and spleen metastases 21 months after diagnosis. PRYST may relapse following surgical treatment; however, surgical resection is currently the optimal treatment method. In this case, bleomycin, etoposide and cisplatin; bleomycin, vincristine and cisplatin; and vincristine and cisplatin chemotherapy regimens were effective for the patient with PRYST, although the tumor was not completely resected. α-fetoprotein (AFP) is an important tumor marker for monitoring PRYST recurrence and observation of elevated serum AFP levels during chemotherapy indicates a poor prognosis.