What is the cause of myositis?

• A. Infection
• B. Inflammation
• C. Infection or inflammation
• D. Autoimmune

Answer: (C)

Myositis is defined by inflammation of skeletal muscle, which leads to symptoms like proximal muscle weakness and fatigue. The inflammation can arise from different causes, most commonly infectious agents that directly invade muscle or trigger an immune response, and from non-infectious inflammatory or autoimmune processes that attack muscle tissue. Because the condition encompasses both infectious and inflammatory pathways, the broadest and best-fitting description of its cause is infection or inflammation. Narrowing it to just infection misses non-infectious inflammatory causes, while naming autoimmune alone reflects only part of the picture—autoimmune inflammatory myopathies are a subset, but not the entirety of myositis.