Polymyositis Other names: Inflammatory myopathy Epidemiology: Age of onset: 40-60 years More common in women Pathogenesis: T-cell mediated: CD4+ T cells Macrophages Cytotoxic T cells Autoantibodies: Anti-Jo-1 antibody Anti-Mi-2 antibody Anti-SRP antibody Anti-PL-7 antibody Clinical Features: Muscle weakness: Proximal muscle weakness (shoulders, hips) Difficulty climbing stairs Difficulty lifting objects Muscle pain: Often mild or absent Other: Skin rash Raynaud's phenomenon Interstitial lung disease Cardiac involvement Diagnosis: Blood tests: Elevated muscle enzymes (CK, aldolase) Autoantibodies EMG: Myopathic pattern Muscle biopsy: Inflammatory infiltrate with CD8+ T cells and macrophages Imaging: MRI: Muscle edema and inflammation Treatment & Management: Corticosteroids: First-line therapy High-dose initial therapy Taper slowly Immunosuppressive agents: Methotrexate Azathioprine Mycophenolate mofetil Cyclosporine Intravenous immunoglobulins: For severe or life-threatening disease Plasmapheresis: May be helpful in acute exacerbations Physical therapy: To maintain muscle strength and function Complications: Respiratory muscle weakness: May require mechanical ventilation Cardiac involvement: Arrhythmias, heart failure Aspiration pneumonia Prognosis: Most patients improve with treatment Some patients may have persistent muscle weakness Risk of relapse is high