Mercury-associated neural epidermal growth factor-like 1 protein (NELL-1) positive membranous nephropathy after use of skin lightening creams

Introduction Membranous nephropathy, one of the common causes of glomerulonephritis worldwide, is reported in association with mercury exposure. Neural epidermal growth factor-like 1 protein is a recently described target antigen in membranous nephropathy.Case series Three woman (ages 17, 39, and 19 years old) presented sequentially for our evaluation with complaints consistent with nephrotic syndrome. All three had nephrotic range proteinuria, hypoalbuminemia, hypercholesterolemia, hypothyroidism, and inactive urinary sediments. Kidney biopsies were performed in the first two patients, which demonstrated findings consistent with membranous nephropathy and positive staining for neural epidermal growth factor-like 1 protein. On discovery that they were all using the same skin-lightening cream, samples of the cream were tested and found to contain between 2,180 parts per million and 7,698 parts per million of mercury. Elevated urine and blood mercury concentrations were also found in the first two patients. All three patients improved following cessation of use and treatment with levothyroxine (all three patients) and corticosteroids and cyclophosphamide in patients one and two.Discussion We hypothesize the role of autoimmunity triggered by mercury exposure in the pathogenesis of neural epidermal growth factor-like 1 protein membranous nephropathy.Conclusion Mercury exposure should be carefully assessed as a part of the evaluation of patients with neural epidermal growth factor-like 1 protein positive membranous nephropathy.