This study aimed to establish the prevalence and clinical associations of anti-HMG-CoA-reductase (anti-HMGCR) in a large UK cohort of 381 patients with juvenile myositis. Anti-HMGCR autoantibodies were detected in 4 patients (1%). These children had no or minimal rash and significant muscle disease. Muscle biopsies were considered distinctive, with widespread variation in fiber size, necrotic fibers, and chronic inflammatory cell infiltrates; all had prolonged elevation of creatine kinase and all ultimately received biologic therapies.
