Antineutrophil cytoplasmic autoantibody (ANCA) positive immunoglobulin A (IgA) nephropathy: Case reports and review of literature

Abstract Background There are reports of circulating antineutrophil cytoplasmic autoantibodies (ANCA) in patients with immunoglobulin A (IgA) nephropathy with an uncertain pathogenic role. Aim of the work To present the findings of myeloperoxidase (MPO) ANCA-positive patients amid a different course of IgA nephropathy with crescents and to discuss the efficacy of immunosuppressive therapy. Case presentation Two cases of IgA nephropathy associated with positive ANCA are reported and a review of the literature data is presented. The first patient presented with a progressive nephropathy and significantly impaired renal function at baseline, whereas in the second patient renal function remained stable over 10 years, despite the recurrent exacerbations of the disease. Both patients had extrarenal manifestations (joint pain and/or anemia) and elevated markers of inflammation (erythrocyte sedimentation rate, C-reactive protein) that are not typical features for IgA nephropathy. In the first case, immunosuppressive therapy with corticosteroids and cyclophosphamide resulted in improvement of kidney function. The second case showed the potential efficacy of rituximab as an induction remission and maintenance therapy for ANCA-positive IgA nephropathy. Conclusion Whether the association of IgA nephropathy with ANCA positivity is coincidental or constitutes a novel entity remains debated. Circulating ANCA can be found in patients with IgA nephropathy. They can be truly pathogenic and contribute to kidney damage and may induce overt systemic vasculitis or at least extrarenal signs and symptoms. ANCA-positive IgA nephropathy can respond to immunosuppressive regimens, including rituximab, similar to patients with ANCA-associated vasculitis (AAV).