Background: Bullous pemphigoid is the most frequent autoimmune blistering dermatologic disease. Induction of pemphigoid has been observed after administration of certain drugs but also after various irradiation procedures. We report a case of pemphigoid strictly confined to the irradiated area.
Case report: A 66-year-old woman had been irradiated 16 years before because of a breast carcinoma. She presented with a blistering rash strictly confined to the irradiated area. The diagnosis of pemphigoid was confirmed with pathologic examination, direct immunofluorescence, direct immunofluorescence of sodium chloride-separated skin, electron microscopy and immunoelectron microscopy. Indirect immunofluorescence and serum immunoblot were also positive. The patient was successfully treated with topical steroids.
Discussion: The location on the area of radiotherapy and the limited character of lesions were unusual. A few cases of pemphigoid strictly localized to the area of radiotherapy have been published. However, in our case, only direct immunofluorescence and immunoelectron microscopy reliably confirmed the diagnosis. The unusual location of this pemphigoid is not due to the regional variation in the expression of the antigen. Other hypotheses concerning the pathogenesis of localized pemphigoid should be examined.