🧬 Not sure where to start? Try searching for your diagnosis above or visit the “Diseases” section.
Anti-Mi-2 (classic dermatomyositis)
Anti-MDA5 (associated with lung involvement)
Anti-TIF1-γ, Anti-NXP2, and others—some linked to cancer risk
Muscles (especially proximal muscles)
Skin
Sometimes lungs or esophagus
Dermatomyositis is a rare autoimmune disease that causes muscle weakness and a distinctive skin rash. The body’s immune system mistakenly attacks healthy muscle and skin tissue, leading to inflammation, pain, and sometimes long-term damage.
It affects both adults and children and can range from mild to severe.
Weakness in the upper arms, thighs, neck, or hips
Trouble climbing stairs, standing from a chair, or lifting arms
Muscle pain or tenderness
Difficulty swallowing (in some cases)
Heliotrope rash: purplish or reddish rash around the eyes and eyelids
Gottron’s papules: raised, scaly bumps over knuckles, elbows, or knees
Red or violet rashes on the face, neck, chest, back, or shoulders
Sun sensitivity (rash worsens with UV exposure)
Thickened, cracked skin on hands (“mechanic’s hands”)
Fatigue
Weight loss
Shortness of breath (if lungs are affected)
Calcinosis (calcium deposits under the skin—more common in children)
The exact cause is unknown, but dermatomyositis is believed to be autoimmune—the immune system mistakenly attacks muscle and skin cells.
Possible contributing factors:
Genetic predisposition
Viral infections
Certain cancers (in adults, dermatomyositis can be a warning sign of an underlying malignancy)
Exposure to UV light may trigger rashes
Doctors use a combination of:
Blood tests (look for muscle enzymes like CK and autoantibodies like anti-Mi-2 or anti-MDA5)
Electromyography (EMG) to test muscle function
Muscle biopsy to look for inflammation
MRI to detect muscle inflammation
Skin biopsy if rash is present
Cancer screening may also be done in adults
There is no cure, but treatment can manage symptoms and slow the disease:
Corticosteroids (like prednisone) to reduce inflammation
Immunosuppressants (like methotrexate or azathioprine)
IVIG (intravenous immunoglobulin) in severe cases
Antimalarial drugs (like hydroxychloroquine) for skin symptoms
Physical therapy to maintain strength and flexibility
Sun protection to prevent rash flare-ups
Many people improve significantly with treatment
Some may go into remission; others have ongoing symptoms
In severe or untreated cases, complications can include permanent muscle weakness, lung disease, or difficulty swallowing
Children with juvenile dermatomyositis often respond well to treatment
Affects approximately 1 in 100,000 people
More common in women than men
Can occur at any age—bimodal peak in children (5–15) and adults (40–60)
Juvenile dermatomyositis makes up about 20% of cases
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS). Dermatomyositis.
https://www.niams.nih.gov/health-topics/dermatomyositis
Mayo Clinic. Dermatomyositis.
https://www.mayoclinic.org/diseases-conditions/dermatomyositis
Rider, L. G., & Miller, F. W. (2013). Classification and treatment of the juvenile idiopathic inflammatory myopathies. Rheumatic Disease Clinics, 39(4), 877–904.
https://doi.org/10.1016/j.rdc.2013.05.004
Sontheimer, R. D. (2002). Would a new name hasten the acceptance of amyopathic dermatomyositis (dermatomyositis siné myositis) as a distinctive subset within the idiopathic inflammatory dermatomyopathies spectrum of clinical illness? Journal of the American Academy of Dermatology, 46(4), 626–636.
https://doi.org/10.1067/mjd.2002.120533
DermNet NZ. Dermatomyositis.
https://dermnetnz.org/topics/dermatomyositis
No frequently asked questions found.
No related content found.
No related content found.
No related content found.
No related content found.
