long-term inflammatory disorder which affects skin and the muscles.
[1] symptoms are a skin rash and worsening muscle weakness over time.[] These may occur suddenly or develop over months.[1] Other symptoms 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] It is a type of inflammatory myopathy.[1] Diagnosis is typically based on some combination of symptoms, blood tests, electromyography, and muscle biopsies.[3]
While 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.[4]
