Classical dermatomyositis

Classical dermatomyositis is an idiopathic inflammatory myopathy characterized by the combination of distinctive skin manifestations and symmetric proximal muscle weakness. It affects both the skin and skeletal muscles, and can also involve the lungs, joints, gastrointestinal tract, and heart. The hallmark cutaneous features include a heliotrope rash (a violaceous or lilac-colored discoloration of the eyelids, often with periorbital edema), Gottron papules (erythematous to violaceous papules or plaques over the knuckles, elbows, and knees), and a photosensitive erythematous rash on the face, neck, upper chest (V-sign), and upper back (shawl sign). Proximal muscle weakness typically manifests as difficulty rising from a chair, climbing stairs, or lifting objects overhead. Patients may also experience dysphagia, fatigue, and arthralgia. Classical dermatomyositis is associated with an increased risk of interstitial lung disease and malignancy, particularly in adults, making cancer screening an important component of management. The disease is thought to result from a complement-mediated microangiopathy affecting the small blood vessels of the skin and muscle. Myositis-specific autoantibodies, such as anti-Mi-2, anti-TIF1-gamma, anti-NXP-2, and anti-MDA5, help define clinical subsets and guide prognosis. Diagnosis is based on clinical features, elevated muscle enzymes (creatine kinase, aldolase), characteristic findings on electromyography, MRI of affected muscles, and muscle biopsy showing perifascicular atrophy and perivascular inflammation. Treatment typically involves high-dose systemic corticosteroids as first-line therapy, often combined with steroid-sparing immunosuppressive agents such as methotrexate, azathioprine, or mycophenolate mofetil. Intravenous immunoglobulin (IVIG) has demonstrated efficacy and is used for refractory cases or as an adjunctive therapy. Rituximab may be considered in treatment-resistant disease. Physical therapy and rehabilitation are essential components of care to maintain muscle strength and function. Photoprotection and topical therapies are used for skin manifestations. Prognosis varies depending on the severity of muscle and organ involvement, the presence of associated malignancy, and response to treatment.

Common questions about Classical dermatomyositis