Dermatomyositis (DM) is a long-term inflammatory disorder which affects 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.The cause is unknown. Theories include that it is an autoimmune disease or a result of a viral infection. Dermatomyositis may develop as a paraneoplastic syndrome associated with several forms of malignancy. It is a type of inflammatory myopathy. Diagnosis is typically based on some combination of symptoms, blood tests, electromyography, and muscle biopsies.While no cure for the condition is known, treatments generally improve symptoms. Treatments may include medication, physical therapy, exercise, heat therapy, orthotics and 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 per 100,000 people per year are newly affected. 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. Signs and symptoms
The main symptoms include several kinds of skin rash along with muscle weakness in both upper arms or thighs.
Epidemiology
Incidence of DM peaks at ages 40–50, but the disease can affect people of all ages. It tends to affect more women than men. The prevalence of DM ranges from one to 22 per 100,000 people. History
The diagnostic criteria were proposed in 1975 and became widely adopted. Amyopathic DM, also called DM sine myositis, was named in 2002. People who died with dermatomyositis
Opera singer Maria Callas (1923–1977) allegedly had dermatomyositis from 1975 until her death. Actor Laurence Olivier (1907–1989) had dermatomyositis from 1974 until his death. American football running back Ricky Bell (1955–1984), the runner-up for the Heisman Trophy in 1976, and the number-one pick in the NFL draft in 1977, died at the age of 29 from heart failure caused by this disease. Rob Buckman (1948–2011) a doctor, comedian, author, and the president of the Humanist Association of Canada. Research
As of 2016, research was ongoing into causes for DM, as well as biomarkers;  clinical trials were ongoing for use of the following drugs in DM: ajulemic acid (Phase II), adrenocorticotropic hormone gel (Phase IV, open label), IMO-8400, an antagonist of Toll-like receptor 7,8 and 9 (Ph II), abatacept (Phase IV, open label), and sodium thiosulfate (Phase II). References

 This article incorporates public domain material from NINDS Dermatomyositis Information Page. United States Department of Health and Human Services. Retrieved 12 December 2016. == External links ==