To investigate the incidence, clinicopathological characteristics and prognosis of IgG4-related kidney disease (IgG4-RKD) of Chinese patients in our center.

All of the renal biopsies from January 2010 to January 2019 were reviewed retrospectively by assessing the involvement of extrarenal organs, measuring serum IgG4 concentrations, and carrying out an immunohistochemical analysis to detect IgG4⁺ plasma cells infiltration at the National Clinical Research Center of Kidney Diseases, Jinling Hospital. Analysis was performed of clinical features, pathological features, and renal prognosis in the patients diagnosed as IgG4-RKD.

Of the 44 784 renal biopsy patients, 22 cases were identified as definite IgG4-RKD. The most common manifestations of IgG4-RKD were proteinuria (86.4%) and renal insufficiency (81.8%), with 68.2% of the patients having extrarenal lesions. Of the IgG4-RKD patients, 86.4% had high serum IgG level, 84.2% high serum IgG4 level, and 45.5% hypocomplementemia. About 90.9% of the IgG4-RKD patients presented as tubulointerstitial nephritis, and 3 patients (13.6%) had membranous nephropathy. About 40.9% of the patients showed storiform fibrosis, and 54.5% showed the bird′s eye pattern in renal tissues. 21 patients were treated with corticosteroids, while two patients failed to follow up. The remaining 20 patients had a median 12-month follow-up, of which one patient progressed to end-stage renal disease, 9 patients showed improved renal function, and 10 patients displayed stable renal function.

IgG4-RKD was a rare disease, often occurred in the middle-aged and elderly people with a male preponderance. The most common manifestations were renal insufficiency and proteinuria. More than half of the patients had extrarenal manifestations. Most of the IgG4-RKD patients had high serum levels of IgG and IgG4, and half of them had hypocomplementemia. The most common type of renal pathology was interstitial nephritis. IgG4-RKD was characterized by a large number of IgG4⁺ plasma cells infiltration, storiform fibrosis, and the bird′s eye pattern in the renal tissues. Glucocorticoid was still the first line choice for treatment of IgG4-RKD.