NELL-1 positive membranous nephropathy in association with antisynthetase syndrome

Membranous nephropathy (MN) is an important cause of nephrotic syndrome and is associated with significant adverse health outcomes including progression to end-stage kidney disease, complications relating to volume overload and increased risk of venous thromboembolism. Primary MN is frequently linked to antibodies against the phospholipase A2 receptor, although a broader range of target autoantigens are emerging. We report a case of a man in his mid-60s who had been recently diagnosed with antisynthetase syndrome presenting with nephrotic syndrome. A kidney biopsy revealed findings in keeping with MN, including positive immunohistochemical staining for the neural epidermal growth factor-like 1 protein (NELL-1) autoantigen. This report highlights a possible novel association between antisynthetase syndrome and NELL-1 positive MN.