LAUSR

There is a rare but documented association between the pemphigoid group of diseases and renal abnormalities, including membranous glomerulonephropathy, with an unknown immunopathogenic mechanism. Here, we report the case of a 68-year-old male patient presenting with oral erosions and blisters and some cutaneous involvement. Serum ELISA reactivity to BP180 was low at 11.6 Units/ml and negative to BP230. Immunoblot (IB) showed strong serum reactivity against recombinant Integrin α6 and BP180, consistent with a diagnosis of mucous membrane pemphigoid (MMP). Non-nephrotic proteinuria and hematuria was identified on screening laboratory exam and evidence of kidney relapse was present with every mucous membrane/cutaneous flare. Examination of the kidney revealed electron-dense deposits along the subepithelial glomerular basement membrane by electron microscopy and diffuse glomerular deposition of IgG. Serum epitope mapping revealed that the major pathogenic antibodies were IgG4 targeting the AA 1080-1107 region of BP180. Serum pre-absorption with recombinant 1080 protein resulted in specific ablation of IB reactivity and a 50% reduction of the indirect immunofluorescence signal. The patient underwent three cycles of rituximab treatment, resulting in remission of both his mucocutaneous and renal disease for a periods ranging from 1 to 1.5 years. This is the first report of a patient with concurrent and cyclic presentation of MMP and membranous glomerulonephritis (MGN). This article is protected by copyright. All rights reserved.