Stripping of the stratum corneum in patients with psoriasis: production of prepinpoint papules and psoriatic lesions.

In patients with psoriasis, partial stripping of the stratum corneum induced minute erythematous and edematous, nonscaling papules six hours to seven days later. These "prepinpoint papules" PPPs) comparable to spontaneous PPPs, which we described earlier, appeared in 75 of 159 patients with active psoriasis but in none of 27 controls; 73% to 91% of these PPPs, depending on the activity of the disease, transformed into pinpoint papules. Histological and histochemical examinations of the PPPs showed infiltrates containing numerous polymorphonuclear leukocytes around the vessels and penetrating into the epidermis, partly destroying it. The earliest change in the epidermis was thinning of the granular layer without other features of psoriasis. Immunoglobulin G and complement deposits on stratum corneum (SC) antigen sites were found in the PPPs initially in about one third, and later in two thirds of the papules, whereas they were present in virtually all of the psoriatic pinpoint papules. Papules induced by stripping, similar to spontaneous PPPs, play a central role in the etiology of at least some forms of psoriasis. Polymorphonuclear leukocyte infiltrates and SC antibody binding are key features of the conversion of PPP to pinpoint psoriatic lesions.