Location of basement membrane type IV collagen beneath subepidermal bullous diseases.

Using standard immunohistochemical methods, routinely processed sections, and a polyclonal antibody to Type IV collagen, we have determined the location of Type IV collagen, a substance located in the lamina densa of basement membrane, in a spectrum of acquired subepidermal bullous diseases. Type IV collagen was attached to the blister roof in five cases of well-established epidermolysis bullosa acquisita and to the blister base in 25 cases of bullous pemphigoid, four cases of dermatitis herpetiformis and 12 cases of porphyria cutanea tarda. Immunohistochemical localization of Type IV collagen in epidermal-dermal basement membrane is a simple, rapid and reliable technique which can be utilized to exclude and possibly to confirm the diagnosis of epidermolysis bullosa acquisita in routinely fixed paraffin-embedded tissues.