Dermatomyositis

Dermatomyositis is a rare condition that causes muscle weakness and distinctive skin rashes. While there is no cure, treatment can help improve muscle strength and clear the skin changes, allowing many people to manage their symptoms and maintain their quality of life.

What is dermatomyositis?
Signs and symptoms
What causes dermatomyositis?
Who does dermatomyositis affect?
How is dermatomyositis diagnosed?
Treatment options
Possible complications
Living with dermatomyositis

What is dermatomyositis?

Dermatomyositis is a rare condition in which swelling and irritation, called inflammation (a response to cell damage), attacks the body’s tissues^[1]. The condition causes muscle weakness and a skin rash. The name comes from Latin words: dermis (skin), myos (muscles), and -itis (inflammation)^[5].

Dermatomyositis is classified as one of the idiopathic inflammatory myopathies (IIMs), which are a group of muscle diseases characterized by chronic muscle inflammation^[2]. A myopathy is a muscle disease, and the condition is often considered an autoimmune condition, though experts are not entirely certain what causes it^[3].

The condition is not common. It can affect both adults and children. In adults, dermatomyositis most often happens in the late 40s to early 60s. In children, it most often appears at ages 5 to 15^[1]. Around 1 in every 100,000 people develop dermatomyositis each year^[8].

Some people with dermatomyositis have only skin symptoms without muscle weakness. This is called clinically amyopathic dermatomyositis (CADM). In this variant, patients have the characteristic skin findings of dermatomyositis but do not have muscle weakness^[2].

Signs and symptoms

The symptoms of dermatomyositis can appear at once or they can come on over time^[1]. The most common symptoms include skin changes and muscle weakness.

Skin changes

A skin rash is often the first sign of dermatomyositis. A violet-colored or dusky red rash appears, most often on the face and eyelids and on the knuckles, elbows, knees, chest, and back. The rash may be harder to see on Black skin or brown skin^[1]. The rash may hurt and itch, and it can sometimes look like a sunburn^[3].

There may also be small bumps on the hands, mainly near the knuckles. These bumps found over the knuckles, elbows, and knees are called Gottron’s papules or Gottron’s sign and often have a raised, scaly appearance^[13]. The skin may be scaly, dry, and rough^[3].

The rash may affect sun-exposed areas, including the cheeks, nose, shoulders, upper chest, and elbows. Other patterns include a rash on the chest and front of the shoulders (called a v-sign rash) or on the neck and back of the shoulders (called a shawl sign rash)^[8]. The fingernails may be ragged, and the skin around the fingernails may be inflamed^[5].

Children may develop white spots on their skin from calcium deposits, called calcinosis^[1].

Muscle weakness

Muscle weakness involves the muscles closest to the center of the body, called the trunk. This includes muscles in the hips, thighs, shoulders, upper arms, and neck. The weakness affects both the left and right sides of the body and tends to get worse over time^[1].

This weakness often leads to difficulty with everyday activities such as climbing stairs, rising from a chair or from the floor, turning in bed, lifting, combing hair, or reaching over the head for something like an item on a shelf^[13]. People may also have trouble sitting upright, getting up from a seated position, or washing their hair^[8].

Muscle pain (myalgia) and joint pain, with or without true arthritis and joint inflammation, can also be part of dermatomyositis^[13]. Over time, the inflammatory process can lead to loss of muscle bulk, called atrophy^[3].

Other symptoms

Other symptoms of dermatomyositis may include weight loss, fever, extreme tiredness (fatigue), and light sensitivity^[4]. The condition can also cause discoloration and bumps on the skin^[8].

Muscles (particularly shoulders, upper arms, hips, thighs, neck)
Skin (face, eyelids, knuckles, elbows, knees, chest, back, scalp)
Esophagus (throat)
Lungs
Heart

What causes dermatomyositis?

Experts don’t know the exact cause of dermatomyositis. Although the cause is unknown, several genetic, immunologic, and environmental factors are believed to play a role in this condition^[2].

Genetic factors

Having certain gene changes may make someone more likely to develop dermatomyositis. Multiple studies have shown that patients with particular human leukocyte antigen (HLA) types are at higher risk of dermatomyositis. These risk factors vary by population and ethnicity^[2].

Immune system involvement

For some reason, the body’s immune system turns against its own muscles and damages muscle tissue in an autoimmune process. In dermatomyositis, immune cells attack the small blood vessels that supply muscles and skin^[3]. Dermatomyositis is considered an autoimmune disorder featuring both humoral and T-cell autoimmune processes^[4].

Although autoantibodies are detected in patients with dermatomyositis, it is unclear whether they play a role in causing the disease^[2]. Eighty percent of adults and sixty percent of children with juvenile dermatomyositis have a myositis-specific antibody (MSA)^[4].

Environmental factors

Environmental factors, particularly infections, may trigger the condition. Viruses such as Coxsackie B virus have been associated with dermatomyositis, but no definitive causal link has been found^[2]^[4].

Dermatomyositis is not a genetic disorder, although there may be genetic factors that make it more or less likely that an inflammatory myopathy will develop^[3].

Who does dermatomyositis affect?

Anyone can be affected by dermatomyositis, but some groups of people are more likely to develop it. The condition affects women more often than men—females are 2-3 times more likely to be affected than males^[8].

In adults, dermatomyositis usually occurs in people in their late 40s to early 60s, particularly those in their 40s and 50s^[1]^[4]. In children, it most often appears at ages 5 to 15^[1]. In children, approximately 3 in every million are affected by juvenile dermatomyositis^[8].

How is dermatomyositis diagnosed?

Dermatomyositis can be difficult to diagnose, particularly if the typical rash is lacking. When patients present with classical signs and symptoms, making the diagnosis is relatively easy^[15]. To diagnose dermatomyositis, a healthcare professional does a physical exam and checks muscle strength^[6].

Diagnosis is typically based on some combination of symptoms, blood tests, electromyography, and muscle biopsies^[4]. The following tests may help with diagnosis:

Blood tests

A blood test may show higher levels of muscle enzymes, which can mean muscle damage. A blood test also can detect autoantibodies linked with certain symptoms of dermatomyositis^[6].

Electromyography (EMG)

For this test, a healthcare professional puts a thin needle electrode through the skin into the muscle. The test measures electrical activity of the muscles as they relax or tighten. Changes in the pattern of electrical activity can confirm a muscle disease. Testing different muscles can show which ones the condition affects^[6].

MRI scan

A magnetic field and radio waves from a computer make detailed pictures of the muscles. An MRI can find swelling and inflammation over a large area of affected muscle^[6].

Skin or muscle biopsy

A healthcare professional removes a small piece of skin or muscle to send to a lab for study. A skin sample can help confirm the diagnosis of dermatomyositis. A muscle biopsy can show muscle damage and inflammation. If the skin biopsy confirms the diagnosis, a muscle biopsy might not be needed^[6].

Chest X-ray and lung tests

A simple chest X-ray can check for signs of the type of lung damage that may happen with dermatomyositis. A healthcare professional may suggest tests to see how well the lungs work and a CT of the chest, especially if the patient has certain autoantibodies that have been linked with a condition of lung scarring called interstitial lung disease^[6].

Treatment options

There’s no cure for dermatomyositis, but treatment can improve muscle strength and help muscles work better. Treatment also can help clear the skin rash^[1]. Although no cure for the condition is known, treatments generally improve symptoms^[4].

Dermatomyositis is a highly treatable disease. Drugs that suppress the immune system (immunosuppressive drugs) are the mainstay of therapy^[9]. Treatment plans are typically individualized to meet the needs of the affected person, and ongoing monitoring is required to optimize the treatment protocol^[9].

Medications

Corticosteroids, particularly prednisone, are often the first-line treatment to reduce inflammation and are the mainstay of therapy for the muscle disease^[9]^[10]. These medications help to reduce inflammation and swelling and suppress damaging autoimmune responses. However, long-term use of high-dose corticosteroid therapy may produce unwanted side effects, such as decreased bone density, increased tissue swelling, and weight gain^[9].

Because most patients develop steroid-related side effects, most doctors recommend using a steroid-sparing immunosuppressive agent early in the course of treatment. For some affected people, therapy with other immunosuppressive drugs may be beneficial. These include:^[9]^[10]

Azathioprine
Methotrexate
Mycophenolate mofetil
Tacrolimus
Cyclosporine

Generally, methotrexate, mycophenolate mofetil, or azathioprine are used first as glucocorticoid-sparing agents for muscle involvement. Response rates to methotrexate have been reported to be approximately 70-80%^[10].

Intravenous immunoglobulin (IVIG) has been recently approved for the treatment of dermatomyositis and may also improve outcomes^[1]^[9]. Additional treatment options used in combination may include the monoclonal antibody rituximab^[9].

For skin symptoms, the antimalarial agent hydroxychloroquine may be used for mild skin predominant dermatomyositis^[9]. Topical corticosteroids can also help with the skin rash^[10].

Physical and supportive therapies

A tailored exercise program can help maintain and improve muscle strength and flexibility. Physical therapists work with patients to create a safe and effective regimen^[14]. Rehabilitative exercise is recommended for both adult and pediatric patients in order to maintain muscle strength, even during the course of active muscle disease^[10].

Occupational therapists help patients adapt their daily activities and use assistive devices to maintain independence and quality of life. For patients experiencing difficulty swallowing or speaking, specialized speech and swallowing therapy can help improve these functions^[14].

Treatment duration

In some cases, affected people may require prolonged maintenance therapy throughout their lives, while in others, therapy may be gradually withdrawn as symptoms resolve. Several years of treatment to suppress the immune system may be necessary^[9].

Sun protection

The skin disease is treated by avoiding sun exposure and by using sunscreens and photoprotective clothing, as the rash is often made worse by sunlight^[5]^[10].

Possible complications

Dermatomyositis may affect other muscles or organs in the body beyond the skeletal muscles and skin. Some possible complications include:

Esophagus problems

If the muscles of the esophagus (passage from the mouth to the stomach) are affected, stomach acid can leak up (reflux) into the esophagus and cause heartburn. This can be treated with acid blocking drugs. If more severely affected, swallowing may be difficult^[5].

For patients with difficulty swallowing and/or gastroesophageal reflux, elevation of the head of their bed and avoidance of eating prior to bedtime are helpful. These simple maneuvers may prevent aspiration pneumonitis. Occasionally, nasogastric tube feeding is needed to increase caloric input^[10].

Lung complications

If the chest wall muscles are affected, some people may develop shortness of breath and have difficulty breathing deeply. Sometimes the lung tissue may be affected and lead to stiffness of the lungs causing breathing difficulties. This can be assessed by testing lung function or scanning the chest^[5]. This condition is called interstitial lung disease^[2].

Heart problems

The heart is also a muscle and can be affected in dermatomyositis, although this is rare. If the heart muscle is involved, this can cause palpitations (an irregular or fast heartbeat) and dizzy spells. The doctor may recommend having a heart tracing or electrocardiogram (ECG) to check for this^[5].

Calcinosis

Calcinosis is the presence of firm yellow or white deposits (lump/spot) of calcium in the skin and sometimes the muscles. This can be painful but may improve once treatment is started. If the lump/spot becomes painful and/or causes problems with movement, surgical removal may be suggested^[5]. Surgical removal of calcium deposits is sometimes recommended to treat painful calcinosis^[9]. Children and adolescents are much more prone to the development of calcinosis, and aggressive early treatment may prevent this complication^[10].

Cancer association

In adults who have dermatomyositis, it is important for doctors to look for signs of any underlying cancer. This occurs in a quarter of adults but very rarely in children^[5]. Around 15% of people with dermatomyositis develop cancer later in their life^[8]. A significant proportion of patients with dermatomyositis have an underlying malignancy, which can alter the prognosis of the condition^[2].

Some of the most common cancers people with dermatomyositis develop include ovarian cancer, lung cancer, lymphoma, breast cancer, and colon cancer^[8]. Unexpected weight loss, a change in bowel habits, bleeding from the back passage, a persistent cough, or blood in the urine are important symptoms which should be reported to the doctor^[5].

Dermatomyositis may develop as a paraneoplastic syndrome associated with several forms of malignancy^[4].

Long-term effects

In rare cases, dermatomyositis can be fatal, especially in the first year after symptoms start^[8]. Dermatomyositis could affect the body for the rest of a person’s life. If it damages muscles badly enough, a person might lose the ability to move or use a part of the body the way they used to. This usually takes years to develop, but some people experience severe muscle weakness earlier than others^[8].

Living with dermatomyositis

Most people improve with treatment, and in some, the condition resolves completely^[4]. While there is no cure for dermatomyositis, symptoms can often be managed with long-term (sometimes life-long) medications and physical therapy^[8].

Self-care practices

Taking good care of yourself is an essential part of healing. There are many self-care recommendations that all people can employ to get and stay healthier. Some suggestions include:^[16]

Get plenty of rest
Maintain and enhance close personal relationships or develop new ones (studies have shown that a strong community and meaningful connections with others makes you healthier)
Have something in your life that brings you rewards or pleasure, such as hobbies, friends, family, or your pet
Give your life a sense of purpose, so you have a reason to fight
Get outside the house, even if you really want to stay inside
Every night, write down three things that you are grateful for
Listen to music, or better yet, sing
Laugh, even if you don’t feel like it (studies have shown that laughter really does make you feel better)
Keep a journal of your progress, so you see that you really are getting better
Accept your disease as a part of you, but don’t let it define you

General measures

Several general measures are helpful in the care of patients with dermatomyositis. Bed rest is often valuable for those with severe inflammation of the muscles. In patients with muscle weakness, especially children, a program of physical therapy is useful to help prevent contractures (muscle shortening/tightness) that can complicate the disease when patients do not fully move their joints^[10].

Dietary management

A balanced diet rich in anti-inflammatory foods can support overall health and well-being. A nutritionist can provide personalized dietary recommendations^[14].

Adapting to life changes

Living with dermatomyositis often forces people to re-define who they are and how they see themselves. Many patients find they learn to live much more in the here and now^[15]. While the journey can be challenging, with proper treatment and support, many people are able to return to a kind of normal life and enjoy rewarding activities, including work and family life.

It’s important to see your healthcare provider right away if you experience any symptoms of dermatomyositis. Some cases take months to develop, but dermatomyositis can develop quickly. The sooner you begin treatment, the more likely it is you can avoid having severe complications^[8].