Skin biopsy from a patient with leukocytoclastic vasculitis showing striking mural fibrin deposition in a postcapillary venule and a concomitant angiocentric mixed neutrophilic and lymphocytic infiltrate. This pattern can be seen in a variety of disorders including hypersensitivity vasculitis, systemic lupus erythematosus, rheumatoid arthritis, mixed connective tissue disease, Sjögren's disease, Behçet syndrome, and relapsing polychondritis.