What is Dermatomyositis

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]