Spotlight on juvenile dermatomyositis

Juvenile dermatomyositis (JDMS) is an inflammatory autoimmune disease affecting approximately three in one million children.

Autoimmune diseases generally occur when the body's immune system begins to malfunction and attack healthy tissue in various parts of the body, causing inflammation and damage. In dermatomyositis, muscle and skin are attacked by inflammation, but the joints, lungs, heart, and intestinal tract can also be affected.

Juvenile dermatomyositis affects girls and boys in equal numbers, and the average age of onset is seven years. While it has no known cure, it is treatable.

The cause of juvenile dermatomyositis remains unknown, although some researchers believe it may be a combination of an inherited susceptibility and an external trigger, such as exposure to excessive sunlight.

Diagnosis of juvenile dermatomyositis

Juvenile dermatomyositis is one type of a much larger disease category called "myositis" (translated, it means "inflammation of the muscle"); approximately 85% of diagnosed myositis is juvenile dermatomyositis. Other kinds of the disease are juvenile polymyositis (JPM) and overlap myositis, which occurs when a child has more than one autoimmune disease, including myositis.

Because some symptoms of dermatomyositis are similar to those of other diseases and because it is rare, it can be difficult for physicians to make the diagnosis. Often, the characteristic skin rashes are first misdiagnosed as eczema or psoriasis. Muscle pain can be mistaken for growing pains or overuse, and weakness can be confused with laziness or sleepiness.

There are several hallmark symptoms of juvenile dermatomyositis, often present at the time of diagnosis. These warning signs include:
  • Rash-including red face rash, scaly patches on arms and legs, and hardened patches on fingers at the knuckles
  • Weakness
  • Muscle pain
  • Fever
  • Fatigue
  • Difficulty swallowing
  • Joint pain and swelling

For more then 50% of children diagnosed with juvenile dermatomyositis, rash is the first sign of the disease. For children with juvenile polymyositis, rashes are less common, and muscle pain and weakness are the most common first signs.

Doctors may order several different types of tests in order to confirm a tentative diagnosis of juvenile dermatomyositis. These may include:
  • Blood tests
  • Urine analysis
  • Muscle imaging tests, including magnetic resonance imaging (MRI), ultrasound scan, and computed tomography (CT) scan
  • Muscle biopsy
  • Electromyography, a test in which a small needle is placed into the muscle, electrically stimulating the muscle, and measuring the response.

Treatment for juvenile dermatomyositis

While there is no cure for juvenile dermatomyositis, treatment advances are allowing more children to live normal lives. Before the use of corticosteroid treatments (also called steroids or prednisone) for juvenile dermatomyositis, one third of children would die from the disease, one third would be severely disabled, and one third would achieve spontaneous remission. Today, the majority of children with the disease who receive treatment recover completely.

Once a diagnosis of juvenile dermatomyositis has been made, the child will usually be referred to a pediatric rheumatologist—a doctor who specializes in treating childhood arthritis diseases. Rheumatologists have at least five years of extra training in addition to regular medical school, and are the best people to treat arthritis diseases. Other specialists usually involved in treating a child with juvenile dermatomyositis include dermatologists, to treat the skin problems associated with the disease.

A well-rounded treatment plan for juvenile dermatomyositis includes medication, education, physiotherapy and occupational therapy, and a healthy diet.

The medications most commonly used to treat the inflammation in juvenile dermatomyositis are oral or IV steroids, like prednisone, which work to slow down the immune system and decrease inflammation. Methotrexate, another medication used to decrease inflammation, is often also used in combination with prednisone.

Another medication, hydroxychloroquine (Plaquenil®), can be used to control the severe rash sometimes present in juvenile dermatomyositis. As well, intravenous immunoglobulin, a drug prepared from human blood, appears to be of benefit in treating severe skin involvement.

Many parents of children with juvenile dermatomyositis note that giving strong medications in the high doses often necessary is one of the most difficult parts of coping with the disease. This is why education is such a critical part of a treatment plan for juvenile dermatomyositis. Like many inflammatory arthritis diseases, early aggressive treatment is vitally important. Parents who have received all of the necessary information are much more likely to be able to help create and implement a well-rounded, effective treatment plan. Children who are treated quickly and effectively have the very best chance of recovering fully.

Physiotherapy and occupational therapy can help to prevent muscle tightening and damage in the early stages of treatment. After the disease is controlled, physiotherapy may be helpful in regaining strength and range of motion. In almost all cases, children are encouraged to return to their regular physical activities as soon as they are able.

Sunscreen is recommended for children with juvenile dermatomyositis, as the rash can become more active with sun exposure. Sunscreen with SPF 21 or higher is usually recommended.

Diet is also an important component of treatment for any disease, and this is especially true for one requiring steroid treatment. Children with juvenile dermatomyositis should eat a diet low in sodium and high in calcium, to help prevent the brittle bones that are a potential side-effect of steroid treatment.