Triple Renal Pathology in a Patient With Myeloperoxidase-Associated Vasculitis, Diabetic Nephropathy, and Immunoglobulin A Nephropathy: A Case Report

Rapidly progressive glomerulonephritis (RPGN) is a nephrologic emergency often caused by antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis.While superimposed diabetic nephropathy can alter the clinical baseline, the concurrent presentation of ANCA vasculitis, diabetic nephropathy, and immunoglobulin A (IgA) nephropathy is uncommon.We present a unique case of a triple-overlap renal pathology.A 56-year-old female patient with a history of type 2 diabetes mellitus presented with acute kidney injury (AKI) with a peak serum creatinine of 5.2 mg/dL, accompanied by macroscopic hematuria and nephrotic-range proteinuria (urine protein-to-creatinine ratio >16,000 mg/g).Serological workup revealed highly elevated myeloperoxidase (MPO) antibodies (677 AI).A renal biopsy confirmed three distinct pathologies: focal crescentic glomerulonephritis, nodular diabetic glomerulosclerosis (Class III), and mesangial IgA deposition.The patient received induction therapy with plasma exchange (PLEX), pulse-dose corticosteroids, and intravenous cyclophosphamide.Due to the cumulative toxicity profile of cyclophosphamide, she was transitioned to maintenance rituximab.To address the residual proteinuria driven by the concurrent diabetic and IgA-associated glomerular injury, sodium-glucose cotransporter-2 (SGLT2) inhibitors and angiotensin receptor blockers (ARBs) were added as supportive therapy.Over 14 months, her serum creatinine stabilized at 1.45 mg/dL, MPO titers decreased to 28 AI, and proteinuria improved to ~6,200 mg/g.This case highlights the critical importance of renal biopsy in diabetic patients presenting with atypical renal function decline or active urinary sediment.Furthermore, it demonstrates that a multimodal therapeutic approach is associated with substantial renal recovery in complex overlapping glomerular diseases.