Polymyositis

Polymyositis is a rare autoimmune muscle disease that causes chronic inflammation and weakness in the skeletal muscles, particularly those closest to the center of the body (like the thighs, hips, shoulders, and upper arms). It typically develops gradually and can make everyday tasks - like climbing stairs or lifting objects - more difficult over time. It is one of a group of diseases called inflammatory myopathies and usually affects adults, especially those between 30 and 60 years old.

Muscle weakness (especially in hips, thighs, shoulders, upper arms, and neck); Difficulty rising from a chair or climbing stairs; Fatigue after walking or standing; Trouble swallowing (dysphagia); Muscle aches or tenderness (less common than weakness); Low-grade fever or weight loss (in some cases); Breathing problems if respiratory muscles are affected.

Autoimmune - the immune system attacks the body's own muscle tissue. While the exact cause is unknown, possible contributing factors include genetic predisposition, viral infections (e.g., HIV, HTLV-1, Coxsackievirus), other autoimmune diseases (e.g., lupus, scleroderma, rheumatoid arthritis), or certain medications or toxins.

Blood tests: Elevated muscle enzymes (CK, aldolase), positive autoantibodies; EMG to detect muscle abnormalities; Muscle biopsy confirms inflammation and damage; MRI identifies areas of muscle inflammation; Autoantibody testing: may include anti-Jo-1 and other myositis-specific antibodies.

Corticosteroids (e.g., prednisone) - first-line therapy; Immunosuppressants (e.g., methotrexate, azathioprine); Physical and occupational therapy to maintain strength and function; IVIG or biologics (like rituximab) for resistant cases; Regular monitoring of lung and heart function if involved.

Many patients respond well to treatment, especially when diagnosed early. May require long-term medication to control inflammation and prevent relapse. In some cases, permanent muscle weakness or disability can occur. Complications can include lung involvement (interstitial lung disease).

Roughly 1 to 8 people per 100,000. More common in women. Onset typically between 30-60 years of age.