Localized Bullous Pemphigoid: Report of a Case with an Immunofluorescence and Electron Microscopical Studies on the Lesional Distribution of 180-KD Bullous Pemphigoid Antigen, β4 Integrin,and Type VII Collagen

A 67-year-old woman with a left-sided hemiplegia had localized bullous pemphigoid demonstrating typical clinical lesions on the left pretibial skin and the radial-side skin of the right forearm. The histology showed a subepidermal blister with extensive hyperkeratosis, hypergranulosis, and acanthosis. Direct immunofluorescence revealed distinct linear deposits of IgG and C3 at the dermo-epidermal junction in the perilesional skin and in the roof of the blisters, but few deposits in nonlesional skin. Electron microscopy revealed separation in the lamina lucida. Indirect immunofluorescence of type VII collagen showed its localization in the blister floor. The distribution of the 180-KD bullous pemphigoid antigen (BPA) and β4 integrin, hemidesmosomal transmembrane proteins, were studied in the lesional skin by indirect immunofluorescence. Both 180-KD BPA and β4 integrin were localized in the blister roof. By immunoelectron microscopy, β4 integrin was detected in small groups on the cell surface facing the blister cavity. Since the epitope of the monoclonal antibody to 180-KD BPA used here is known to be localized at a distance of 20 to 50 nm from the membrane surface and this epitope retained in the blister roof, it appears that the blister was produced in the deep lamina lucida. The lesions were cleared with topical 0.05% clobetasole propionate ointment.