Primary retroperitoneal paraganglioma mimicking a ureteral tumor: a case report and literature review.

Paragangliomas (PGLs) arise from chromaffin cells of the extra-adrenal sites along the sympathetic and/or the parasympathetic chain. Majority of the PGLs occur in the abdomen. When retroperitoneal PGLs produce symptoms of compression or invasion of adjacent organs, they could be misdiagnosed as a tumor of adjacent organs. Here, we report a rare case of ureteral obstruction caused by an extra-adrenal retroperitoneal PGL that mimicked a ureteral tumor. A 46-year-old female presented with a 2-year history of hypertension. Routine laboratory tests were unremarkable. The computed tomography (CT) scan showed a hypervascular mass located in the left mid-ureteral section. Ureteropyelography revealed left ureteral obstruction at the level of L4 to L5 vertebrae and hydroureteronephrosis. Cystoscopy confirmed left ureteral obstruction. Based on the clinical and imaging findings, a left ureteral tumor was suspected preoperatively. The tumor was completely resected, and the involved segment of the ureter was removed. No significant enlarged lymph nodes were seen in the pelvic cavity and retroperitoneum. A histopathological examination of the tumor confirmed retroperitoneal PGL partly infiltrating the ureter. The patient's blood pressure returned to the normal range postoperatively. Our case demonstrates the importance of considering extra-adrenal PGL in the differential diagnosis of retroperitoneal tumors.