Neural epidermal growth factor-like 1 protein-positive membranous nephropathy in renal allografts: A series of 6 patients.

Membranous nephropathy (MN) is a major cause of nephrotic syndrome, and neural epidermal growth factor-like 1 protein (NELL1) is the second most common inciting antigen. An increasing number of exposures and diseases have been associated with NELL1⁺ MN. There are limited data on NELL1 following kidney transplantation with only 1 previously reported case. In this report, we describe 3 cases of recurrent and 3 cases of de novo NELL1⁺ MN. None of the patients in this series had known triggers of MN, such as malignancy or associated medications (including lipoic acid, bucillamine, tiotropin, or indigenous medicines). This suggests that NELL1, although not a podocyte antigen, may present as an idiopathic disease or transplantation may serve as an exposure for the development of NELL1⁺ MN.