Analysis of the characteristics of IgG4-related membranous nephropathy with literature review / 中华风湿病学杂志

ABSTRACT

Objective:By retrospectively analyzing 6 cases of IgG4-related membranous nephropathy (IgG4-MN), combined with literature review, to explore the clinical and renal pathological characteristics of the disease, and improve clinicians' understanding of the disease.Methods:The data of six patients with biopsy-proven IgG4-MN in the nephrology center of our hospital during April 2017 to January 2021 were collected. At the same time, we reviewed the literature systematically and summarized the clinicopathological characteristics.Results:Six male patients with the age ranged fom 55 to 75 years old were described. Urine protein level was (3.1±2.1) g/24 h, 3 cases (50%) showed nephrotic syndrome and 4 cases (67%) had elevated serum creatinine. The median creatinine level was (103±24) μmol/L. Six cases (100%) had elevated serum immunoglobulin (Ig)E level, and 4 cases (67%) had elevated IgG4. M-type phospholipase A2 receptor (PLA2R) was positive in 1 case (17%) and tubulointerstitial nephritis (TIN) was present in 6 cases. The review of the literature suggested that a total of 49 cases with IgG4-MN were reported, including 6 cases in this report. There were 40 males (40/46, 87%), with a age range of (61±12) years old, 32 cases (32/49, 65%) showed nephrotic syndrome range proteinuria, and the proportion of serum IgG and IgG4 increase was 61%(20/33) and 88% (36/41), respectively, 13 cases (13/15, 87%) had elevated serum IgE level, 47% (14/30) had low-complement C3 and 44%(12/27) had low-complement C4 level. The main organs involved were pancreas (15/37) and lymph nodes (16/37). Renal pathology showed TIN in 74%(36/49). Electron dense deposition was mainly subepithelial deposits. 7%(2/28) were positive for anti-PLA2R antibody in serum, 17%(3/18) were positive for PLA2R in kidney tissue, 6%(1/18) were suspected positive for PLA2R in kidney tissue, and 8%(1/12) were dual positive in blood and kidney tissue.Conclusion:IgG4-MN usually presents with nephrotic range proteinuria or nephrotic syndrome in middle-aged and elderly patients. Most of them are complicated with TIN and other organ involvement. A certain proportion of patients are PLA2R positive in IgG4-MN, and whether it is primary or secondary MN needs further study.