Key Features of Dermatomyositis
Characteristics
Dermatomyositis (DM) affects characteristic areas of the skin and muscles, with different sites of systemic involvement (Figure 1-2).

Skin manifestations
A detailed physical exam is essential for making the correct diagnosis of DM. Key clinical features of DM involve skin manifestations, muscle involvement, and extra-muscular manifestations. Common cutaneous features of DM include Gottron’s papules and heliotrope eruption, as well as Gottron’s sign (Table 1-2). Less common cutaneous DM manifestations appear in Table 1-3.
Muscle Involvement
Clinical evidence of myositis is found in ~80% of DM patients. Muscle involvement typically occurs as symmetric progressive proximal muscle weakness affecting the shoulder and pelvic girdle without significant muscle pain. In cases of myalgias, or muscle pain, it is important to evaluate for fasciitis which can occur in DM.
More severe muscular…
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Characteristics
Dermatomyositis (DM) affects characteristic areas of the skin and muscles, with different sites of systemic involvement (Figure 1-2).

Skin manifestations
A detailed physical exam is essential for making the correct diagnosis of DM. Key clinical features of DM involve skin manifestations, muscle involvement, and extra-muscular manifestations. Common cutaneous features of DM include Gottron’s papules and heliotrope eruption, as well as Gottron’s sign (Table 1-2). Less common cutaneous DM manifestations appear in Table 1-3.
Muscle Involvement
Clinical evidence of myositis is found in ~80% of DM patients. Muscle involvement typically occurs as symmetric progressive proximal muscle weakness affecting the shoulder and pelvic girdle without significant muscle pain. In cases of myalgias, or muscle pain, it is important to evaluate for fasciitis which can occur in DM.
More severe muscular involvement includes dysphagia and dysphonia of the pharyngeal and esophageal striated muscles. Involvement of the neck muscles may lead to difficulty holding the head up, leading to head drop.
Weakness of the diaphragm and accessory muscles of breathing may contribute to respiratory insufficiency and aspiration pneumonia risk.
Systemic manifestations
Interstitial Lung Disease
Interstitial lung disease (ILD) is the most common systemic manifestation of DM, occurring in about 15-30% of patients. It is one of the leading causes of hospitalization and death in patients with DM. Early symptoms suggestive of ILD include dry cough and progressive dyspnea. Severity can range from mild to rapidly progressive. Median time to onset of ILD is 16–18 months after DM diagnosis, though it can develop anytime during the disease course and may occur despite treatment. Lung involvement is particularly concerning in patients with anti-MDA5 DM, though it is currently not possible to predict which patients with anti-MDA5 will develop RP-ILD.
Cardiac Involvement
Cardiac involvement in DM is associated with poor prognosis. Cardiac manifestations of DM may include subclinical diastolic dysfunction, arrhythmias, myocarditis, pericarditis, pericardial effusion/tamponade, cardiomyopathy, myocardial fibrosis, and congestive heart failure (CHF). CHF is the most frequently reported manifestation, occurring in 10-15% of patients. CHF presents with symptoms of dyspnea on exertion, orthopnea, and nocturnal dyspnea.
Although often asymptomatic and subclinical, some cardiac manifestations are clinically significant. In patients with DM, systemic inflammation, glucocorticoid use, and underlying traditional cardiovascular risk factors may lead to increased risk of cardiovascular events such as acute myocardial infarction, ischemic stroke, deep venous thromboses, and pulmonary emboli, which account for a large proportion of deaths due to DM.
Gastrointestinal Manifestations
Gastrointestinal manifestations of DM occur in 18-20% of DM patients and include dysphagia affecting pharyngeal and upper esophageal skeletal muscle. Dysphagia can be mild to severe, sometimes associated with choking and a risk of aspiration pneumonia, and sometimes requiring feeding tube placement. Severe and life-threatening gastrointestinal manifestations are rare and could include ulcerations, hemorrhage, perforation, and intestinal ischemia/infarction.
Other Manifestations
Dermatomyositis can cause non-erosive polyarthritis or arthralgia of the small joints of the hands, resulting in joint pain or swelling. Overlap inflammatory arthritis, similar to rheumatoid arthritis, can occur with DM.
Malignancy occurs in 15–27% of patients with DM and may present as paraneoplastic syndrome or with malignancies of different organs. Systemic symptoms such as fever, malaise, and unintentional weight loss may herald an occult malignancy. Male gender, older age at onset, the presence of dysphagia, and the absence of interstitial lung disease are other predictive factors of malignancy.
There is decreasing malignancy risk over time, and the first 3 years following DM diagnosis confers the highest-risk period for malignancy diagnosis. Risk factors associated with malignancy include presence of TIF1γ autoantibodies, age >45 years at DM diagnosis, male sex, dysphagia, and cutaneous ulceration.
Malignancy screening recommendations have not reached consensus, but it is well accepted that all patients with dermatomyositis should undergo age appropriate malignancy screening. If patients have refractory DM with associated risk factors noted above, additional intensive screening may be required.
References
- Aggarwal, R., Schessl, J., Charles-Schoeman, C. et al. Safety and tolerability of intravenous immunoglobulin in patients with active dermatomyositis: results from the randomised, placebo-controlled ProDERM study. Arthritis Res Ther 26, 27 (2024).
- ArgenX Press Release. Argenx Advances Clinical Development of Efgartigimod SC in Idiopathic Inflammatory Myopathies. November 20, 2024. https://argenx.com/content/dam/argenx-corp/newsroom/press-release-pdfs/PressRelease_argenx_ALKIVIA_Ph2_20241120.pdf.coredownload.inline.pdf