An unusual presentation of membranous nephropathy with primary and secondary features: a case report

Membranous nephropathy (MN) is a common cause of nephrotic syndrome in adults, broadly classified as primary or secondary based on etiology and pathologic findings. We present a single unusual case report of a 75-year-old woman with an 11-year course of MN featuring concurrent characteristics of both primary and secondary disease. On two separate kidney biopsies for the same patient, she demonstrated histopathologic features consistent with Class V lupus nephropathy alongside positive PLA₂R staining - a combination that creates significant diagnostic uncertainty. Despite the overlapping features, the patient achieved remission on two separate occasions using different immunosuppressive regimens: cyclosporine initially, followed by Mycophenolate mofetil and prednisone upon relapse over a decade later. This case contributes to the emerging literature on PLA₂R positivity in lupus membranous nephropathy and highlights the diagnostic and therapeutic challenges clinicians face when primary and secondary MN features coexist. The long-term follow-up and dual treatment response on a single patient reported here add to a limited body of published cases and carry implications for management of this increasingly recognized overlap syndrome.