Cutaneous necrotizing venulitis in patients with cystic fibrosis.

Palpable purpura was noted to occur late in the course of some patients with cystic fibrosis. Skin biopsy specimens showed necrotizing venulitis characterized by a perivenular infiltrate composed of neutrophilic leukocytes, fibrin, hypogranulated mast cells, and endothelial cell necrosis. Circulating immune complexes were detected. Recurrent pulmonary infections and the chronic administration of therapeutic agents provide sources of potential antigens.