[Retroperitoneal Castleman's disease occurred around the bilateral upper ureters. A case report].

: A 45-year-old woman with a history of right regional dull pain was referred to our hospital for evaluation of right hydronephrosis. CT and MRI showed a solitary mass (1 x 1 cm, L1-L2 level) at the right upper ureter. Laboratory data were within the normal range. A right nephrectomy was carried out under a clinical diagnosis of primary right ureteral tumor. The pathohistological diagnosis of surgical specimen was plasma cell type of Castleman's disease. One year after surgery, the patient was rehospitalized for azotemia and left hydronephrosis. Abdominal CT revealed a solitary mass (1.5 x 1.5 cm) located at left upper ureter similar to that on her right side. We diagnosed that the mass lesion was due to asynchronous Castleman's disease, so we performed steroid therapy. After the treatment, mass had disappeared. The patient is uneventful for two years. This is the first case reported in the Japanese literature describing Castleman's disease occurred around the bilateral upper ureters.