A Unique Case of Myositis.

Abstract

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a rare systemic small-vessel disease, with heterogeneous clinical manifestations. While arthralgia and myalgia are common in the disease course, frank myositis is exceedingly rare. Immune-mediated necrotizing myopathy (IMNM) is a subtype of idiopathic inflammatory myopathies (IIMs), characterized by severe myositis. We report herein a case of prominent diffuse myositis with shared features of AAV and IMNM.