Pemphigoid nodularis: two case studies and analysis of autoantibodies before and after the development of generalized blistering.

We report 45- and 61-year-old women with generalized prurigo nodularis-like eruption whose clinical, histologic and immunopathologic features were consistent with the diagnosis of pemphigoid nodularis. In one case, nodular lesions preceded the onset of generalized blistering by two years and in the other, no definite blister nor erosion was seen except for some appearing on the soles during the course of the disease. Western immunoblotting of EDTA-separated epidermal extracts revealed that the 230-kD bullous pemphigoid (BP) antigen was recognized by circulating autoantibodies in the patient sera, but the 180-kD BP antigen was not. The 180-kD BP antigen was recognized weakly by immunoblotting of the 180-kD BP antigen NC16a domain fusion protein, which shows high detection sensitivity. These findings suggested that weak reactivity of autoantibodies with either whole or a part of the 180-kD BP antigen molecule in some way accounts for negligible or localized blister-formation in this disorder. However, no particular change was noted in the reactivity with 180-kD BP antigen between the patient serum obtained before and after the development of generalized blistering. It is possible that different factors from the changes in serum reactivity with BP antigens may be involved in initiating generalized blistering.