Nephrology pictures: pemphigus vulgaris and membranous nephropathy

Abstract

Figure 1 depicts a 39-year-old woman hospitalized because of diffuse skin bullous lesions that spread out over the trunk, back, limbs and scalp, as well as ulcers in the oral cavity and esophagus. The lesions were painful and progressed quickly to ulcers and erosions. Past history included active smoking and successful treatment for intraepithelial cervix neoplasia. One year earlier she presented with edema, hypoalbuminemia, hypercholesterolemia and nephrotic range proteinuria. Membranous nephropathy (MN) was diagnosed by kidney biopsy; antibodies anti-PLA2R were positive. She was started on prednisone and cyclophosphamide on alternate months, but was lost to follow-up during the COVID pandemic and did not complete treatment. Therefore, after restarting follow-up, four months before the current hospitalization, she was started on cyclosporine, which was discontinued due to oral ulcers. At time of the current admission, the patient had subnephrotic proteinuria, hypoalbuminemia, but no edema and her serum creatinine was normal. The diagnosis of pemphigus vulgaris (PV) was confirmed by skin biopsy, and immunohistochemistry showed the presence of IgG4 subclass antibody in the epithelial tissue (Fig. 2). She received pulse and oral steroids (methylprednisolone 1 g for three days and prednisolone 1 mg/kg/d) along with azathioprine (2 mg/kg/d), as standard treatment for the pemphigus, with incomplete response at 6 weeks. She was therefore switched to Rituximab, allowing slow healing of the skin lesions together with decrease in proteinuria. Five months after admission she was in remission and prednisone was tapered. The relationship between bullous skin diseases and glomerulonephritides has been increasingly recognized [1, 2]. Bullous pemphigoid, IgA pemphigus and pemphigus foliaceus have been reported in association with MN [3, 4]. Pemphigus vulgaris has been described in association with thymoma [5], and this is, to the best of our knowledge, the first case associated with PLA2R positive MN. The common underlying mechanism likely involves the production of autoantibodies, specifically IgG4, directed against different skin and kidney antigens (Fig. 2) [1].