[Two cases of IgG4-related systemic disease arising from urinary tract].

Case 1: The patient was a 68-year-old man. Abdominal computed tomography performed during hospitalization for the close observation of a pituitary gland tumor, showed a right renal mass. Percutaneus needle biopsy revealed IgG4-related disease of the kidney. Pituitary gland tumor biopsy also indicated that the lesion was associated with IgG4-related disease. The pancreas did not show abnormalities. The patient was treated with prednisolone, and both renal and pituitary lesions markedly decreased in size. Case 2: the patient was an 80-year-old man. Right hydronephrosis was observed, and computed tomography showed a right pelvic tumor. Right renal pelvic tumor was diagnosed, and the patient underwent right nephroureterectomy. Pathological examination showed that this tumor was also associated with IgG4-related sclerotic disease. IgG4-related disease tends to occur in multiple organs. This condition should be considered when treating patients with multiple sclerotic diseases. However, in some patients, the disease may be localized to a single site. Further studies are required to elucidate the characteristics of IgG4-related disease.