Inflammatory Myositis

Myositis is an infrequently encountered condition marked by muscle inflammation. Symptoms of this condition can include skin problems, muscle weakness, and possibly affect other organs. Additionally, individuals with myositis may experience systemic symptoms such as weight loss, fatigue, and low-grade fever.

Causes

Myositis can be triggered by various factors, including injury, medications, infections, inherited muscle diseases, or autoimmune disorders. Sometimes, the cause remains unknown, or idiopathic.

• Injury
  Intense exercise can lead to a mild form of myositis. A more severe muscle injury known as rhabdomyolysis, where muscles rapidly break down, can also be associated with myositis.
  
• Medicines
  Various medications can induce myositis. Statins, used to lower cholesterol, are among the most common drugs that can lead to muscle pain and, in rare cases, myositis.
  
• Infection
  Viral infections, such as the common cold, are the most frequent infectious cause of myositis. Bacterial, parasitic, and fungal infections can also trigger it. Viruses like COVID-19 have been identified as rare causes. Benign acute childhood myositis has been observed in children following viral infections.
  
• Inherited Muscle Diseases
  Several inherited myopathies can present with secondary myositis, including conditions like calpainopathy, dysferlinopathy, facioscapulohumeral muscular dystrophy, dystrophinopathy, and LMNA-associated myopathy.
  
• Autoimmune Disorders
  Autoimmune responses targeting specific body proteins, including muscles, can cause myositis. The primary types of idiopathic myositis, also known as inflammatory myopathies, include dermatomyositis, polymyositis, and inclusion body myositis, which typically test positive for autoantibodies. Other autoimmune diseases, such as systemic lupus erythematosus, may also produce myositis-like symptoms.