Histopathology of anti-p200 pemphigoid

Anti-p200 pemphigoid is an autoimmune subepidermal blistering disease characterized by circulating and tissue-bound antibodies against a 200-kd glycoprotein (p200) of the human dermis. We reviewed 10 lesional biopsies from seven patients with anti-p200 pemphigoid in an attempt to define typical histopathologic features of this disease. All biopsy specimens showed subepidermal blistering and a moderate to dense inflammatory infiltrate in the upper dermis. Immunohistochemical analysis localized type IV collagen to the dermal side of the blister, suggesting that split formation occurred within the lamina lucida of the cutaneous basement membrane. The inflammatory infiltrate was composed almost exclusively of neutrophils in six biopsies and contained a mixture of neutrophils and eosinophils in the remaining four. In three specimens, microabscess formation in the papillary dermis adjacent to the blister cavity was noted. Neutrophilic and eosinophilic spongiosis was found in five and three biopsies, respectively. We conclude that histopathology of anti-p200 pemphigoid is characterized by subepidermal blistering and a superficial inflammatory infiltrate, which is usually dominated by neutrophils but occasionally contains significant numbers of eosinophils. While this microscopic picture mimics that of linear IgA disease, dermatitis herpetiformis, or bullous pemphigoid, it should also alert a histopathologist to the possibility of anti-p200 pemphigoid and prompt immunofluorescence and immunoblotting studies for definite diagnosis or exclusion of this autoimmune subepidermal blistering disease.