IgA Nephropathy with ANCA Vasculitis: A Case Section with Diagnostic and Therapeutic Challenges

The co-existence of IgA nephropathy (IgAN) and Anti-Neutrophil Cytoplasmic Antibody (ANCA)-Associated Vasculitis (AAV) is rare but presents a distinct diagnostic and therapeutic challenge. IgAN is the common glomerulonephritis characterised by mesangial IgA deposition, while AAV typically involves small-vessel vasculitis associated with Myeloperoxidase (MPO)-ANCA or PR3- ANCA positivity. Although these are classically considered separate entities, emerging evidence suggests that ANCA positivity can be seen in a subset of IgAN patients, often associated with more aggressive renal involvement and a broader systemic inflammatory response. We describe three cases of biopsy-proven IgA nephropathy with AAV. All patients had histological features consistent with both mesangial IgA deposition and crescentic glomerulonephritis, along with elevated ANCA titers. Presentations varied from constitutional symptoms to a severe pulmonary-renal syndrome. All patients received immunosuppressive therapy including corticosteroids and cyclophosphamide, followed by maintenance with mycophenolate mofetil. Two patients showed improvement in renal function, while one progressed to end-stage kidney disease requiring dialysis. This case series underscores the importance of considering ANCA testing in IgA nephropathy with atypical or rapidly progressive features and supports a combined immunosuppressive treatment approach in such overlapping pathologies.