Malignancy-associated membranous nephropathy: focus on diagnosis and treatment.

BACKGROUND: The clinicopathological features of malignancy-associated membranous nephropathy have been described previously, but information about diagnosis and treatment remains limited. METHODS: Patients with malignancy-associated membranous nephropathy in a tertiary hospital in China between June 2012 and October 2021 were retrospectively reviewed. RESULTS: Forty-two patients with malignancy-associated membranous nephropathy were identified. Compared to patients with idiopathic membranous nephropathy, patients with malignancy-associated membranous nephropathy were older and less frequently showed glomerular phospholipase A2 receptor staining (37.9% vs 85.0%) and IgG4 predominant deposition (66.7% vs 95.0%). At diagnosis of membranous nephropathy, the malignancy was unknown in 67% (28/42) of patients and was detected only by tumor screening. Among the 19 patients with concurrent diagnosis of cancer and biopsy-proven membranous nephropathy, 15 received anticancer treatment alone initially. Six of the 10 patients who attained cancer remission achieved remission of membranous nephropathy, while none of the 5 patients without remission of cancer did, suggesting a causal relationship between the two diseases. Some patients with persistent or relapsing membranous nephropathy following cancer remission achieved remission of membranous nephropathy after immunosuppressive therapy. Over a median follow-up of 24 months, 25% (10/40) of patients died, mainly due to neoplasia. CONCLUSIONS: Tumor screening is important in patients with membranous nephropathy, especially in elderly patients and patients with negative phospholipase A2 receptor or non-IgG4 predominant deposition. Remission of membranous nephropathy can be observed following remission of cancer in some cases. Immunosuppressive therapy may be considered if membranous nephropathy does not remit after remission of cancer.

Analysis of Glomerular IgG Subclasses Switch in Idiopathic Membranous Nephropathy Classified by Glomerular Phospholipase A2 Receptor Antigen and Serum Antibody.

BACKGROUND: The role of IgG subclass in idiopathic membranous nephropathy (IMN) was unclarified. Recent study found IgG subtype switches from IgG1 to IgG4 in the early pathological stage in IMN. The profile of IgG subclass in phospholipase A2 receptor- (PLA2R-) related and PLA2R-unrelated IMN was unrevealed. Our study is aimed at testifying whether IgG subclass switch existed in PLA2R-related and PLA2R-unrelated IMN, respectively. METHODS: Our study retrospectively enrolled 157 Chinese patients with biopsy-confirmed IMN between September 2017 and November 2019. We measured glomerular PLA2R antigen and serum anti-PLA2R antibody to classify the patients into PLA2R-related (n = 132) and PLA2R-unrelated (n = 25) subgroup. We evaluated glomerular IgG subclass by immunofluorescence (IF) predominance. Our study defined IgG subclass deposition as predominant if the IF score was higher than the other three and ≥1 +, or as codominant if the IF intensity was equal to any other and ≥1 +. We explored the relationship between IF predominance of glomerular IgG subtype and electron microscopic (EM) stages of IMN. RESULTS: We did not find statistical difference of predominant or codominant rate (pre/co-rate) among EM stages in any subclass (P > 0.05). Pre/co-rate of IgG3 linearly associated with EM stage in total and PLA2R-related subgroup (P = 0.044, P = 0.013). PLA2R-related subgroup showed higher IgG4 intensity (2.1 ± 0.6 vs. 1.6 ± 0.7, P = 0.001) and pre/co-rate of IgG4 in stage 1 (97% vs. 57%, P = 0.015) than PLA2R-unrelated group. We found no difference of IgG subclass pre/co-rate in different EM stages or linear association between pre/co-rate of IgG1, IgG2, IgG4, and EM stages (P > 0.05). CONCLUSIONS: Pre/co-rate of IgG3 declined with EM stage in total and PLA2R-related subgroup. We did not find IgG subclass switches from IgG1 to IgG4 in either IMN patients or subgroups.