A Patient of Crescentic Glomerulonephritis with Positive Anti Myeloperoxidase Antibodies and Immunoglobulin a Deposits on Immunofluorescence: The Conundrum Continues

Abstract

Immunoglobulin (Ig)A nephropathy is the commonest type of primary glomerulonephritis (GN) in the world, with an estimated incidence of 2.5/100000 adults/year. It can co-exist with systemic conditions and is a common cause of crescentic GN. Antineutrophilic cytoplasmic antibody (ANCA) associated vasculitis can present as necrotizing, crescentic GN with pauci immune features on immunofluorescence on renal biopsy. There have been previous case reports of the presence of ANCA and IgA nephropathy in the same patient. Such patients more often have systemic signs and tend to have worse kidney function at presentation as compared to ANCA negative IgA nephropathy patients. However, they tend to show better response to immunosuppressive medication. We report a case of a young Asian lady who presented with acute kidney injury secondary to crescentic GN. She was found to have positive serum anti myeloperoxidase antibodies and also IgA deposits in the mesangium on renal biopsy. She was managed with steroids and cyclophosphamide, but her renal function did not improve after 6 months of induction therapy. This case reiterates the conundrum faced by the clinician in the interpretation of a combination of positive anti MPO antibodies with mesangial hypercellularity, positive mesangial staining for IgA and presence of crescentic nephritis. It also describes the variation in response to therapy in such cases.