Pustulosis vegetans.

Sterile pustules and crusted vegetative plaques on the trunk and limbs developed in a 24-year-old man. They left cribriform scars after healing. Histologically, the lesions showed epidermal proliferation and pustulosis resembling that found in "pyoderma vegetans" and pemphigus vegetans. The lesions were effectively suppressed in two months by the topical application of methoxsalen followed by UV-A irradiation. Studies revealed that the chemotactic activity of polymorphonuclear leukocytes (PMNs) in the patient's peripheral blood was enhanced and that an extract of lesional crusty scales showed the presence of a PMN chemotactic factor. This factor had a molecular weight near 12,500 daltons similar to that reported in psoriasis scales. We speculate that tissue destruction due to complement activation, possibly induced by immune complex-mediated reactions in the dermis, provoked a process of transepithelial elimination of the inflammatory products.