Suction-induced basal cell cytolysis in the Weber-Cockayne variant of epidermolysis bullosa simplex.

In the Weber-Cockayne form of epidermolysis bullosa simplex (EBS-WC), trauma induces blisters which are confined to the palms and soles. Histologically, basal cell cytolysis is seen. We studied 6 patients with EBS-WC to determine the ultrastructural level at which artificially-induced suction blisters form. Blisters were raised by application of a suction blister cup to uninvolved forearm skin, the cup being connected to a negative pressure of 200 mm of mercury. The blisters were biopsied and examined by light and electron microscopy. On light microscopy, all biopsies showed marked vacuolization of keratinocytes in the lower two-thirds of the epidermis, and in all but one there was a cleavage plane through the basal keratinocytes. These findings were confirmed by electron microscopy in 4 patients. The separation through the basal cells is in contrast to the situation in normal individuals in whom cleavage occurs below the level of the basal cells, within the lamina lucida. Thus, even apparently normal skin from non-acral sites has the same structural abnormality as the affected acral sites in EBS-WC.