Retrospective analysis of de-identified archival biopsy specimens taken from skin ulcers and sural nerves of 29 patients with histologically proven PAN-associated MSV vasculitis. Patients met the classification and definitional criteria of the American College of Rheumatology3 and Chapel Hill Consensus Conference.4 Specimens were obtained from Johns Hopkins University, University of Pennsylvania, and Ameripath Inc. Biopsy technique, depth and site within the ulcer, and histologic findings were evaluated by the same dermatopathologist (C.H.N). Peripheral ulcer areas were defined to include the ulcer edge and surrounding nonulcerated skin, whereas nearby central ulcer areas included the areas near the ulcer center. Both areas were determined by the referring physician and histopathologically. Fisher exact and χ² tests were performed.