Bucillamine, Membranous nephropathy, Proteinuria relapse-free survival rate, Rheumatoid arthritis, 30% eGFR decline-free survival rate, Medicine, Science

Abstract To evaluate the pathological and clinical course differences between bucillamine‑induced membranous nephropathy (BCL-MN) and primary membranous nephropathy (p-MN). This retrospective cohort study included 29 BCL-MN patients and 98 p-MN patients at two hospitals from 2000 to 2019. We compared the kidney biopsy findings and clinical course between the BCL-MN and p-MN groups, focusing on pathological differences, proteinuria relapse rates, and 30% or greater decrease in the eGFR. While kidney function and proteinuria levels were similar, histopathological differences were observed. BCL-MN group showed less spike formation in LM and more stage I cases. IgG1 was predominant in BCL-MN group, contrasting with IgG4 in p-MN group. BCL-MN group had significantly higher prevalence of segmental subepithelial deposits (66.7% vs. 24.7%, p