An immunoelectron microscopy study of the relationship between herpes gestationis and polymorphic eruption of pregnancy.

Five patients with typical bullous herpes gestationis and five patients with polymorphic eruption of pregnancy were studied. Shave biopsies were taken from both involved and uninvolved skin and examined by routine immunofluorescence. They were also examined by immunoelectron microscopy employing a multistep peroxidase-antiperoxidase technique which has been shown to be more sensitive than immunofluorescence. Despite the increased sensitivity of immunoelectron microscopy all cases of polymorphic eruption of pregnancy were completely negative. Although there is a considerable clinical and histopathological overlap between herpes gestationis and polymorphic eruption of pregnancy our findings indicate that these conditions are pathogenetically distinct and should be classified as separate disorders.