Successful Treatment of a 42-Year-Old Man with Concurrent Anti-Glomerular Basement Membrane Disease and Anti-Phospholipase A2 Receptor Antibody-Positive Membranous Nephropathy: A Case Report

BACKGROUND Anti-glomerular basement membrane (anti-GBM) disease is an autoimmune disease mediated by deposit of antibodies to collagen type IV in glomerular and alveolar basement membranes. Membranous nephropathy (MN) is characterized by thickening of the glomerular capillary walls due to immune complex deposition. Anti-GBM disease can occur in conjunction with a second disease. However, simultaneous presentation of anti-GBM disease with MN has rarely been described. Here, we present a case of a 42-year-old man with combined anti-GBM disease and anti-phospholipase A2 receptor (PLA2R) antibody-positive membranous nephropathy. CASE REPORT A 42-year-old man was admitted due to acute kidney injury and proteinuria. Serum anti-GBM antibody was positive and the patient was diagnosed with anti-GBM disease without alveolar hemorrhage on day 2. Double-filtration plasmapheresis (DFPP) was performed starting on day 3, and intravenous methylprednisolone and cyclophosphamide were administrated. Kidney biopsy was performed on day 24 and demonstrated co-existence of anti-GBM disease and PLA2R antibody-positive MN. After discharge, the patient continued to receive oral corticosteroid and serial injections of cyclophosphamide over a course of 6 months. His kidney function recovered and MN reached partial remission. CONCLUSIONS We report the case of a 42-year-old man with concurrent anti-GBM disease and PLA2R antibody-positive MN. Early diagnosis and prompt treatment with a combined regimen of corticosteroid, cyclophosphamide, and DFPP were essential factors in the patient's successful recovery.