Sarcoidosis presenting as bilateral hydronephrosis.

We report an unusual case of sarcoidosis associated with bilateral hydronephrosis. The patient was a 53-year-old Japanese woman who presented with dysuria and urinary incontinence. Computed tomography of the abdomen showed bilateral hydronephrosis caused by a retroperitoneal mass, surrounded by enlarged retroperitoneal lymph nodes. Histological examination of the mass demonstrated noncaseating epithelioid cell granulomas involving the retroperitoneal lymph nodes. Corticosteroid therapy led to complete resolution of the retroperitoneal mass and hydronephrosis. This case emphasizes that sarcoidosis should be included in the differential diagnosis of a retroperitoneal mass.