Anti-BP230 type mucous membrane pemphigoid with desquamative gingivitis: A case report

Mucous membrane pemphigoid (MMP) is an autoimmune subepithelial/subepidermal blistering disease characterized by linear deposition of immunoglobulin G (IgG), IgA, and/or C3 in the basement membrane zone (BMZ) and predominant mucosal lesions involving the oral cavity and conjunctivae. Here, we describe a case of a 58-year-old Japanese man with MMP. Intraoral examination revealed desquamative gingivitis in the upper and lower gingivae. No conjunctival or cutaneous lesions were observed. Histopathological examination revealed a subepithelial split with inflammatory cell infiltration of the epithelial and connective tissues. Direct immunofluorescence revealed a linear deposition of C3 in the BMZ. IgG autoantibodies against BP230 were detected using an enzyme-linked immunosorbent assay. Indirect immunofluorescence using 1 mol/L NaCl-split skin sections revealed no reactivity for serum IgG or IgA. Immunoblotting using normal human epidermal extract as a substrate did not detect IgG reactivity against the 230-kDa antigen. Based on the above results, the definitive diagnosis of MMP with anti-BP230 antibody alone was established. Our case was categorized as low-risk MMP. The patient was treated with 0.1% triamcinolone acetonide ointment, oral minocycline, and oral nicotinamide, which improved the oral erosions. However, the mechanism underlying IgG autoantibody production against intracellular BP230 remains unclear. Further research and more such case studies are necessary to elucidate the mechanism of anti-BP230 antibody production and the clinical feature of anti-BP230 type MMP.