musculoskeletal and connective tissue disorders
Autoimmune Myositis
Key Points
Muscle weakness caused by myositis is most often proximal. Heliotropic rash and Gottron papules are specific for dermatomyositis. To establish the diagnosis, look for characteristic rash, muscle weakness, elevated creatine kinase level, and muscle changes on electromyography or MRI. Unless patients have the characteristic skin findings, do a muscle biopsy to confirm the diagnosis. Consider screening patients ≥ 40 years with dermatomyositis and patients ≥ 60 years with polymyositis for cancer. Treat patients with corticosteroids and other immunosuppressants. 