Abstract
Patient. A 65-year-old man was admitted with a large primary retroperitoneal tumor and an increased β-human chorionic gonadotropin (β-HCG) serum level. A germ cell tumor was suspected; however, a computed tomography-guided biopsy failed to enable tumor classification. After two courses of chemotherapy, the β-HCG serum level had returned to the normal level and a diagnostic laparotomy with incisional biopsy was performed. The immunohistochemical examination of the specimen identified the tumor as a retroperitoneal pleomorphic leiomyosarcoma.Discussion. Tumor markers play only a marginal role in the work-up of patients with soft tissue sarcomas. In men with suspected retroperitoneal sarcomas, however, the determination of germ cell tumor markers occasionally enables a preoperative distinguishing of primary retroperitoneal germ cell tumors with considerable consequences for management. In this setting, a retroperitoneal tumor associated with a moderately elevated β-HCG is a diagnostic dilemma, and surgeons should be aware of the pitfall of a β-HCG-producing leiomyosarcoma in the differential diagnosis.