Idiopathic inflammatory myopathy

Idiopathic inflammatory myopathy is a subacute or chronic inflammatory myopathy characterized by muscle fiber necrosis, regeneration, and inflammatory cell infiltration in the interstitial tissue. The peak incidence in children is between 10 and 14 years old, and in adults, it is between 45 and 54 years old. The average age of onset in males is greater than in females, but the incidence in females is significantly higher than in males. The main symptoms are weakness and pain in the proximal limbs, neck, and pharyngeal muscles, which can manifest as difficulty raising the arms, inability to lift the legs, and inability to stand up after squatting.