Figure 1

Histopathologic evidence of vasculitis, neurogenic atrophy, and myositis. A-E (HES stain), muscle cryostat sections showing: A, necrotizing vasculitis of medium-sized artery with abundant eosinophils; B, atrophic angulated fibers, nuclear clumps, and split fibers; C, isolated necrotic fibers; D, phagocytosis of non-necrotic fiber; and E, fiber with rimmed vacuole. F , MHC-1 immunohistochemical stain showing variable sarcolemmal and sarcoplasmic expression. Bar (in A, mm): A, 0.1; B, 0.2; C, 0.18; D, 0.12; E, 0.07; F, 0.4.