Dermatomyositis

Dermatomyositis is an autoimmune connective tissue disease characterized by prominent skin and muscle damage. The main clinical features include lilac-purple or red edematous erythema on affected skin (face, neck, periorbital areas, etc.), muscle pain, and muscle weakness. The disease can also involve other organs throughout the body. When only muscles are affected without skin involvement, it is called polymyositis. Dermatomyositis can occur alone or overlap with other autoimmune diseases such as systemic lupus erythematosus, scleroderma, and rheumatoid arthritis. Patients may have various specific antibodies in the blood, including anti-PM-1, anti-Jo-1, and anti-Mi-2. The peak incidence of dermatomyositis is 5-15 years in children and 30-50 years in adults, with a slight female predominance. The onset may be related to tumors, infection, drugs, endocrine, and metabolic factors. Most cases of dermatomyositis follow a chronic progressive course with a good prognosis. In patients over 40 years old, 20-30% have associated malignant tumors. Intradermal tests with autologous tumor extract may show positive reactions, and symptoms improve after treatment or removal of the tumor, indicating that autologous tumor tissue antigens participate in the pathogenesis. Some findings suggest that the cause may be related to viral or Toxoplasma infection. Like other immune diseases, this condition often causes multi-organ functional damage. The most prominent and severe damage is to the lungs, commonly referred to as "interstitial pneumonia." Patients may experience cough, shortness of breath, and in severe cases, pulmonary interstitial fibrosis and respiratory failure. In the advanced stages, treatment efficacy is extremely poor, so early detection is crucial. In the early stage, hormones and some immunosuppressants are commonly used for treatment.