Symptoms vary from person to person. They often develop gradually but may come on suddenly. Common signs and symptoms of dermatomyositis include:
• Muscle weakness – Dermatomyositis commonly affects the big muscle groups in the neck, upper arms and thighs, leading to:
o Difficulty climbing stairs, difficulty getting up from a chair or out of a car
o Difficulty reaching for overhead objects
o Difficulty swallowing, regurgitation of food/fluids from the nose
o Changes in the voice: softer, weaker
o Difficulty breathing
• Skin and circulation
o Raynaud’s phenomenon (fingers and/or toes changing colour in response to cold or stress)
o A purplish hued rash on the eyelids (heliotrope rash)
o Red/purplish bumps over the joints of the fingers, knuckles, elbows and/or knees (Gottron’s papules) or over the palms (inverse Gottron’s papules)
o Rashes over the upper chest (V sign) or back (shawl sign)
o Purplish or reddish rashes over the outer parts of the thighs (Holster sign)
o Rashes may worsen when exposed under the sun
o Rough, cracked and thickened skin on the hands (mechanic’s hands) and around the fingernails (ragged cuticles)
o Skin ulcers
o Small hard calcium deposits under the skin (calcinosis)
• Lungs
o Shortness of breath and dry cough
• Heart
o Shortness of breath, palpitations, chest pain, leg swelling
• Joints
o Joint pain, swelling and stiffness
• General symptoms
o Fatigue
o Fever
o Weight loss or loss of appetite
Dermatomyositis cannot be diagnosed based on a single test alone. Doctors use a combination of symptoms, physical examination signs, blood tests, and organ-specific assessments to make this diagnosis.
Key steps in diagnosis include:
• Detailed medical history and physical examination
• Laboratory tests including blood counts, inflammatory markers, muscle enzymes such as creatine kinase (CK) and aldolase, and assessment of the liver and kidney function
• Blood antibody tests: looking for specific antibodies that are commonly seen in dermatomyositis such as anti-Jo1, TIF-1-gamma, NXP-2, Mi-2, MDA-5 etc.
• Specialised tests to look for muscle inflammation: these include electromyography (EMG) which assess the muscle’s response to electrical signals, and MRI scans of the affected muscle groups which may show inflammation
• Organ-specific tests:
o Lung function tests (blowing tests) and CT scans of the chest to look for any inflammation or scarring in the lungs
o Echocardiogram (ultrasound of the heart)
• A tissue biopsy of the skin or muscles may be performed to support the diagnosis of dermatomyositis
• Screening for cancer: as adult patients with dermatomyositis have increased risk to develop cancers, a comprehensive screen for cancer is usually performed. This includes CT scans of the body, endoscopy (putting a small camera into the mouth, through the rectum and nose), and for women: mammogram and PAP smear
Early and accurate diagnosis allows for closer monitoring and timely treatment, which can help prevent serious complications.
There is currently no cure for dermatomyositis, but treatment can help control symptoms, protect organs, and improve quality of life. Care is usually coordinated by a rheumatologist, often together with other specialists such as lung, heart and skin doctors. Your treatment plan will be carefully tailored to your symptoms, preferences, and goals of care. Patients who are treated adequately can continue to lead normal active lives.
• Corticosteroids are fast-acting medications that effectively suppress the immune system. These are usually started at high doses (intravenous injections through the veins or oral), then reduced over time.
• Immunosuppressive agents are used in addition to steroids to reduce the need for long-term steroids and for control of disease activity.
o These include methotrexate, azathioprine, mycophenolate mofetil, tacrolimus and cyclophosphamide
o Biologic agents are targeted medications often given intravenously through the veins, e.g. rituximab
o Newer targeted therapies have also been used in patients with severe disease or do not respond to the above treatment e.g. tofacitinib
• Intravenous immunoglobulin (IVIg) may be given in severe disease, especially when there are feature suggesting weakness in the neck and respiratory muscles which can be life-threatening. IVIg consists of purified antibodies collected from donors and helps to reduce inflammation quickly.
• Topical creams may be used to treat rashes
Physiotherapy and occupational therapy is recommended to maintain mobility and muscle strength. Additionally, other medical conditions are addressed as part of holistic care, such as high cholesterol, diabetes, and osteoporosis. To prevent infections when on high doses of immune suppression medications, prophylactic antibiotics and certain vaccinations are encouraged (e.g. influenza, pneumococcal, COVID-19, shingles and respiratory syncytial virus).
