Abstract

Membranous nephropathy (MN) is a leading cause of nephrotic syndrome (NS). The remission rate of MN remains limited, and effective strategies for refractory MN are not established. We present the case of a 49-year-old Japanese woman with severe NS caused by MN. Kidney biopsy revealed glomerular basement membrane thickening with granular deposition of immunoglobulin G (IgG) and complement component 3. IgG subclass analysis showed predominant IgG1 deposition, with weak IgG2 and IgG3 deposition. Phospholipase A2 receptor (PLA2R) deposition was equivocal in the first kidney biopsy and negative in the second. Serum anti-PLA2R antibody was not detected. Electron microscopy revealed subepithelial, subendothelial, and mesangial electron-dense deposits. Detailed screening revealed no significant abnormalities other than appendiceal findings, suggesting secondary MN associated with appendiceal infection. Although combined therapy with prednisolone, cyclosporine, rituximab, and low-density lipoprotein apheresis was administered during the first 6 months, remission of MN was not achieved. During dialysis, initiated because of kidney failure, long-term multidisciplinary management, including control of appendiceal infection and inflammation and initiation of angiotensin II receptor blocker therapy, ultimately led to remission of MN and discontinuation of dialysis. Overall, even refractory MN requiring dialysis may have a reversible clinical course with careful conservative management and long-term follow-up.

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