Chronic sclerosing pyelitis with an increased number of IgG4-positive plasma cells.

IgG4-related disease has been recently described. This disease occurs in various anatomic locations including pancreas, biliary tract, liver, retroperitoneum, kidney, breast, lung, thyroid gland, prostate, salivary gland, lacrimal gland, and lymph node. In this article, we report the first case of IgG4-related disease arising in the renal pelvis. A 49-year-old Japanese woman was found to show left hydronephrosis by a medical checkup. Histological examination of the renal pelvic tumor showed IgG4-related disease. Her postoperative serum IgG4 was elevated, and this was compatible with IgG4-related disease. Systemic examination showed swelling of major and minor salivary glands and the lacrimal glands, and biopsy of the minor salivary gland revealed the finding of IgG4-related disease. Finally, pathologists and clinicians should be aware of the possibility that the renal pelvis may be involved in IgG4-related systemic disease.