Primary membranous nephropathy presenting with crescentic glomerulonephritis 25 years after initial presentation: A case report

Membranous nephropathy (MN) is a common cause of nephrotic syndrome. Rarely, it can present with rapidly-progressive renal failure and hematuria. While this may be due to lupus nephritis, superimposed anti-glomerular basement membrane (GBM) disease, or antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis, there have been rare reports of anti-GBM - and ANCA-negative crescentic glomerulonephritis presenting in primary membranous nephropathy (pMN). We present the case of a patient with long-standing pMN who developed acute deterioration of renal function and was found to have a flare of MN along with crescentic glomerulonephritis (GN) despite a negative serum ANCA, anti-GBM, and antinuclear antibody (ANA) work-up. He was started on dialysis and inununosuppressive therapy, and eventually recovered enough renal function to become dialysis-independent. A brief review of available literature suggests that crescentic GN presenting with pMN is a rare but established entity. Much more rarely has it been reported to occur in patients with previously-diagnosed pMN. In these contexts, crescentic GN may be occurring as the most severe manifestation of pMN rather than as a separate entity. Immunosuppressive therapy is often given, however, prognosis is guarded as half of patients will have worsening renal function and a quarter will develop end-stage renal disease.