Polymorphic pemphigoid.

We describe 20 patients with a chronic polymorphic eruption; they shared clinical, histopathological, and therapeutic features of both dermatitis herpetiformis and bullous pemphigoid (BP). In 14 of these 20 cases, direct and indirect immunofluorescence studies corresponded to BP. The remaining six patients showed IgA deposits in a linear pattern at the basement membrane zone, and two of these six showed IgA pemphigoid antibodies in their sera as well. No significant clinical and histological differences were detected in the patients, in connection with the immunological findings. Furthermore, one patient's condition, which was studied by repeated immunofluorescence examinations, changed from a linear IgA pattern and a negative indirect test to a linear IgG pattern and a positive reaction for IgG pemphigoid antibodies. We concluded that these cases constitute a polymorphic variant of BP.