Junctional blisters in acquired bullous disorders of the dermal-epidermal junction zone: role of the lamina lucida as the mechanical locus minoris resistentiae.

The level of cleavage was determined in a variety of acquired bullous diseases of the dermal-epidermal junction zone (bullous pemphigoid, dermatitis herpetiformis, porphyria cutanea tarda and epidermolysis bullosa acquisita). We used an indirect immunofluorescence technique to examine the basal membrane zone with anti-type IV collagen and anti-laminin antisera and bullous pemphigoid sera. The majority of blisters examined proved to be junctional, including those from disorders hitherto considered to be dermolytic. Dermolytic cleavage was encountered only sporadically in microvesicles of dermatitis herpetiformis, in one small vesicle and in one out of five large blisters of porphyria cutanea tarda and in a large lesion of epidermolysis bullosa acquisita. We conclude that in acquired bullous disorders of the dermal-epidermal junction zone the preferential site of split formation is the lamina lucida which appears to act as a locus minoris resistentiae; dermolytic split formation of substantial extent occurs only when the sublaminal fibrillar apparatus is mechanically compromised.