Vesicular pemphigoid is a rare clinical variant in which the cutaneous manifestations show a striking overlap with dermatitis herpetiformis. Patients present with numerous small tense vesicles that may be symmetrical, intensely pruritic and therefore associated with conspicuous excoriation.
In a biopsy taken from an established blister, the changes are most often those of an inflammatory (cell-rich) variant. The blister, which is subepidermal, is typically unilocular and covered by attenuated epithelium . In early lesions the roof epidermis may appear unaffected or show occasional to even confluent necrotic basal keratinocytes. The blister contents include coagulated serum, fibrin strands and large numbers of inflammatory cells including conspicuous eosinophils . Variable numbers of neutrophils may be present.
The underlying dermis is inflamed and usually shows widespread severe edema. An infiltrate of eosinophils and mononuclears surrounds the blood vessels and extends between the adjacent collagen bundles. Leukocytoclasis is not seen and features of vasculitis are not present. The adjacent papillary dermis is often edematous and, very occasionally, eosinophil microabscesses are a feature . Exceptionally rarely, neutrophil microabscesses may be seen, raising diagnostic confusion with dermatitis herpetiformis. Eosinophilic spongiosis is also sometimes evident in the adjacent epidermis.