Dermatomyositis
| Dermatomyositis | |
|---|---|
| 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 |
| Complications | Calcinosis, dysphagia, interstitial lung disease, heart disease (rarely), joint pain, other autoimmune conditions |
| Usual onset | 40s to 50s |
| Duration | Long term |
| Causes | Autoimmune (Type III hypersensitivity) |
| Risk factors | Other autoimmune conditions, ovarian cancer, breast cancer, lung cancer, other cancers |
| Diagnostic method | Based on symptoms, blood tests, electromyography, muscle biopsies |
| Differential diagnosis | Polymyositis, inclusion body myositis, scleroderma |
| Treatment | Medication, physical therapy, exercise, heat therapy, orthotics, assistive devices, rest |
| Medication | Corticosteroids, methotrexate, azathioprine |
| Frequency | ~ 1 per 100,000 people per year |
Dermatomyositis (DM) is a long-term inflammatory autoimmune disorder which affects the skin and the muscles. Its symptoms are generally a skin rash and worsening muscle weakness over time. These may occur suddenly or develop over months. Other symptoms may include weight loss, fever, lung inflammation, or light sensitivity. Complications may include calcium deposits in muscles or skin.
Dermatomyositis is an autoimmune disorder featuring both humoral and T-cell autoimmune processes. Dermatomyositis may develop as a paraneoplastic syndrome associated with several forms of malignancy. It is known to be associated with several viruses, especially coxsackievirus, but no definitive causal link has been found. Dermatomyositis is considered a type of inflammatory myopathy. Diagnosis is typically based on some combination of symptoms, blood tests, electromyography, and muscle biopsies. Eighty percent of adults and sixty percent of children with juvenile dermatomyositis have a myositis-specific antibody (MSA).
Although no cure for the condition is known, treatments generally improve symptoms. Treatments may include medication, physical therapy, exercise, heat therapy, orthotics, assistive devices, and rest. Medications in the corticosteroids family are typically used with other agents such as methotrexate or azathioprine recommended if steroids are not working well. Intravenous immunoglobulin may also improve outcomes. Most people improve with treatment and in some, the condition resolves completely.
About one in 100,000 people receive a new diagnosis of dermatomyositis each year. The condition usually occurs in those in their 40s and 50s with women being affected more often than men. People of any age, however, may be affected. The condition was first described in the 1800s.