Electron microscopic features in generalized pustular psoriasis.

Basal keratinocyte herniations (BKH) have been used as markers of psoriatic activity. Abnormal multipolypoid forms herniating through large gaps in the basal lamina have been found to characterize biopsies from psoriatic patients with concomitant alpha 1-antitrypsin deficiency, and appear to be a marker of excessive proteolytic activity. The finding of similar multipolypoid BKH in patients with generalized pustular psoriasis of the von Zumbusch variety (but not in patients with psoriasis vulgaris), in the absence of concomitant alpha 1-antitrypsin deficiency, would support the concept of the presence of large amounts of proteolytic enzymes in the dermis of patients with this syndrome. The large proportion of BKH directly associated with dermal neutrophils, and the presence of clusters of high-density BKH overlying collections of dermal neutrophils, suggests that neutrophilic proteases are largely responsible for BKH formation in patients with this syndrome.