05/20/2025
Derm Index: What You Should Know About Dermatomyositis
Dermatomyositis (DM) is a rare, chronic, autoimmune disorder characterized by both inflammatory muscle disease and distinct cutaneous manifestations. Although it can affect individuals of all ages, sexes, and ethnicities, the disease demonstrates a higher prevalence in adult females. DM is often triggered by an immune-mediated process in genetically predisposed individuals, which may be exacerbated by environmental factors such as infections, drugs, or malignancies. Additionally, DM frequently coexists with other connective tissue diseases like systemic lupus erythematosus, rheumatoid arthritis, scleroderma, Sjogren’s syndrome, and mixed connective tissue disease.
Pathophysiology and Risk Factors
While the exact etiology of dermatomyositis remains unknown, the disease is believed to result from autoimmune dysregulation, where the immune system attacks the skin and muscles. In some cases, the condition may be associated with underlying malignancies, particularly in older adults. The frequency of cancer in adults with DM ranges between 10% and 50%, with an increased risk for cancers such as ovarian, breast, lung, gastric, and other female ge***al cancers. This relationship underscores the need for thorough oncologic screening in adult patients diagnosed with DM. In pediatric cases, calcinosis, or the deposition of calcium salts under the skin, can develop, leading to firm, yellow-to-white lumps, especially in the knuckles and elbows.
Clinical Manifestations
Dermatomyositis often presents with non-specific systemic symptoms such as fatigue, weakness, and muscle pain. The skin manifestations may precede or accompany the muscle symptoms. One of the most notable dermatologic features is the heliotrope rash, a purple discoloration affecting the eyelids, which is characteristic of the condition. Gottron’s papules, which are scaly, erythematous lesions over the knuckles, are another hallmark of DM. Other skin findings include poikiloderma, a condition marked by thin, atrophic skin, visible blood vessels, and hyperpigmented spots in sun-exposed areas such as the face, neck, shoulders, and upper chest.
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