Asymptomatic extra-adrenal paraganglioma masquerading as retroperitoneal sarcoma.

A 41-year-old man without clinical symptoms was referred for treatment of an enlarging retroperitoneal tumor. Enhanced computed tomography showed a well-defined and heterogeneously enhanced tumor, 4 cm in size, in the dorsal portion of the pancreas. A low-density nodule was detected in the left adrenal gland, 10 mm in diameter. Retroperitoneal sarcoma and nonfunctional left adrenal tumor were suspected, and surgical treatment was performed. During excision of the retroperitoneal tumor, blood pressure was extremely elevated when the tumor was compressed. Blood pressure normalized after excision of the tumor; thus, a diagnosis of paraganglioma was favored over that of retroperitoneal sarcoma. The left adrenal gland was resected together with the adrenal tumor. Microscopically, the tumor cells of the retroperitoneum had round to oval nuclei, and abundant granular amphophilic cytoplasm proliferated in nest-like fashion. Extra-adrenal retroperitoneal paraganglioma was considered, and the adrenal tumor was diagnosed as cortical adenoma. In patients with retroperitoneal tumor, even in the absence of clinical symptoms, we should keep in mind the possibility of extra-adrenal paraganglioma.