Skin
One form the rashes take is called "heliotrope" (a purplish color) or lilac, but may also be red. It can occur around the eyes along with swelling, but also occurs on the upper chest or back what is called the "shawl" (around the neck) or "V-sign" above the breasts and may also occur on the face, upper arms, thighs, or hands. Another form the rash takes is called Gottrons sign which are red or violet, sometimes scaly, slightly raised papules that erupt on any of the finger joints (the metacarpophalangeal joints or the interphalangeal joints). Gottrons papules may also be found over other bony prominences including the elbows, knees, or feet. All these rashes are made worse by exposure to sunlight, and are often very itchy, painful, and may bleed.If a person exhibits only skin findings characteristic of DM, without weakness or abnormal muscle enzymes, then he or she may be experiencing amyopathic dermatomyositis (ADM), formerly known as "dermatomyositis sine myositis". Muscles
People with DM experience progressively worsening muscle weakness in the proximal muscles (for example, the shoulders and thighs). Tasks that use these muscles: standing from sitting, lifting, and climbing stairs, can become increasingly difficult for people with dermatomyositis. Other
Around 30% of people have swollen, painful joints, but this is generally mild.In some people, the condition affects the lungs, and they may have a cough or difficulty breathing. If the disease affects the heart,  arrhythmias may occur.
Around 80% of people with DM test positive for ANA and around 30% of people have myositis-specific autoantibodies which include antibodies to aminoacyl-tRNA synthetases (anti-synthetase antibodies), including antibodies against histidine—tRNA ligase (also called Jo-1); antibodies to signal recognition particle (SRP); and anti-Mi-2 antibodies.Magnetic resonance imaging may be useful to guide muscle biopsy and to investigate involvement of internal organs; X-ray may be used to investigate joint involvement and calcifications.A given case of dermatomyositis may be classified as amyopathic dermatomyositis if only skin is affected and no muscle weakness for longer than 6 months is seen according to one 2016 review, or two years according to another. Classification
Dermatomyositis is a form of systemic connective tissue disorder, a class of diseases that often involves autoimmune dysfunction.It has also been classified as an idiopathic inflammatory myopathy, along with polymyositis, necrotizing autoimmune myositis, cancer-associated myositis, and sporadic inclusion body myositis.A form of this disorder that occurs prior to adulthood is known as juvenile dermatomyositis. Treatment
No cure for dermatomyositis is known, but the symptoms can be treated. Options include medication, physical therapy, exercise, heat therapy (including microwave and ultrasound), orthotics and assistive devices, and rest. The standard treatment for dermatomyositis is a corticosteroid drug, given either in pill form or intravenously. Immunosuppressant drugs, such as azathioprine and methotrexate, may reduce inflammation in people who do not respond well to prednisone. Periodic treatment using intravenous immunoglobulin can also improve recovery.