Dermatomyositis | |
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Discrete red areas overlying the knuckles in a person with juvenile dermatomyositis. These are known as Gottron's papules. | |
Specialty | Rheumatology |
Symptoms | Rash, muscle weakness, weight loss, fever[1] |
Complications | Calcinosis, lung inflammation, heart disease[1][2] |
Usual onset | 40s to 50s[3] |
Duration | Long term[1] |
Causes | Unknown[1] |
Diagnostic method | Based on symptoms, blood tests, electromyography, muscle biopsies[3] |
Differential diagnosis | Polymyositis, inclusion body myositis, scleroderma[3] |
Treatment | Medication, physical therapy, exercise, heat therapy, orthotics, assistive devices, rest[1] |
Medication | Corticosteroids, methotrexate, azathioprine[1] |
Frequency | ~ 1 per 100,000 people per year[3] |
Dermatomyositis (DM) is a long-term inflammatory disorder which affects the skin and the muscles.[1] Its symptoms are generally a skin rash and worsening muscle weakness over time.[1] These may occur suddenly or develop over months.[1] Other symptoms may include weight loss, fever, lung inflammation, or light sensitivity.[1] Complications may include calcium deposits in muscles or skin.[1]
The cause is unknown.[1] Theories include that it is an autoimmune disease or a result of a viral infection.[1] Dermatomyositis may develop as a paraneoplastic syndrome associated with several forms of malignancy.[4] It is a type of inflammatory myopathy.[1] Diagnosis is typically based on some combination of symptoms, blood tests, electromyography, and muscle biopsies.[3]
Eighty percent of adults with adult-onset dermatomyositis have a myositis-specific antibody (MSA).[5]
Sixty percent of children with juvenile dermatomyositis have a myositis-specific antibody (MSA).[6]
Although no cure for the condition is known, treatments generally improve symptoms.[1] Treatments may include medication, physical therapy, exercise, heat therapy, orthotics, and assistive devices, and rest.[1] Medications in the corticosteroids family are typically used with other agents such as methotrexate or azathioprine recommended if steroids are not working well.[1] Intravenous immunoglobulin may also improve outcomes.[1] Most people improve with treatment and in some, the condition resolves completely.[1]
About one per 100,000 people per year are newly affected.[3] The condition usually occurs in those in their 40s and 50s with women being affected more often than men.[3] People of any age, however, may be affected.[3] The condition was first described in the 1800s.[7]
Cal2006
was invoked but never defined (see the help page).Myositis-specific autoantibodies (MSAs) can now be identified in 80% of adults.
Approximately 60% of patients with JDM are positive for a myositis-specific antibody (MSA).