Symptoms and signs of Idiopathic Inflammatory Myopathies

Weakness or loss of strength, which is almost always proximal, in other words, affecting the muscles closest to the central part of the body, except in the case of IBM where the flexor muscles of the fingers and quadriceps are typically affected. Proximal strength loss is apparent in the arms (shoulder girdle), evidenced by difficulty in raising them above the head, and in the legs (pelvic girdle), causing difficulties when getting up from a low chair or the toilet. Normally, no pain is associated with this muscle weakness.

Skin lesions. Dermatomyositis is characterised by typical skin lesions which may appear prior to, during or after muscular weakness. The characteristic skin lesions are heliotrope rash (purplish in colour around the eyes); erythematous rash on the face, knees, elbows, neck, chest ("V" sign), back and shoulders; Gottron papules (above the knuckles on the hands) and "mechanic's hands" (like those of a construction worker who does not wear gloves). More rare are subcutaneous calcifications that sometimes produce painful ulcers. Ulcers on the fingers and palms are often seen in forms of myositis that are associated with the anti-MDA-5 antibody.

Lung involvement. IIM can affect the lungs in various ways. The most common is undoubtedly interstitial lung disease (ILD), where the lung tissues become inflamed and damaged. More rarely, it can also affect the intestines and heart. Finally, weakness of the respiratory muscles can lead to respiratory failure. This is sometimes the way the disease presents.