Dermatomyositis is a rare inflammatory disease. It is an inflammatory myopathy, a condition that occurs when muscles become inflamed. It is one of only three known inflammatory myopathies. The most common symptom is weakness in the muscles. Dermatomyositis can affect both adults and children. Although there’s no cure for the illness, you may experience a period when you have no symptoms.
The exact cause of dermatomyositis isn’t known. However, similarities between it and autoimmune diseases have caused doctors to believe that there’s a link between the two. Autoimmune diseases occur when the body’s disease-fighting cells called antibodies attack healthy cells. Having a compromised immune system (from a viral infection or cancer, for example) may also contribute to the development of dermatomyositis.
Although anyone can develop dermatomyositis, it’s most common in adults between the ages of 40 and 60 and children between the ages of 5 and 15. The disease affects women more often than men.
In most cases, the most obvious symptom is a skin rash on the face, chest, nails, or elbows that can appear to be red or violet.
You may also have muscle weakness that gets worse over weeks or months. This muscle weakness usually starts in your neck, arms, or hips and can be felt on both sides of your body.
Other symptoms you might experience are:
- muscle pain
- muscle tenderness
- problems swallowing
- lung problems
- hard calcium deposits underneath the skin (mostly seen in children)
- unintentional weight loss
Dermatomyositis is considered the easiest of the inflammatory muscle diseases to diagnose because of the rash associated with it. Your doctor may be able to diagnose you with amyopathic dermatomyositis (dermatomyositis of your skin) if you don’t have any muscle weakness. Other tests that may be performed to confirm the diagnosis are:
- magnetic resonance imaging (MRI)— to look for abnormal muscles
- electromyography— to record electrical impulses that control your muscles
- blood analysis— to check the levels of muscle enzymes and autoantibodies (those that attack normal cells)
- muscle biopsy— a sample of muscle tissue will show inflammation and other problems associated with the disease
- skin biopsy—a skin sample will show changes caused by the disease
Although there is no cure for dermatomyositis, treatment can improve the condition of your skin and muscle weakness. Prompt treatment improves your chances of avoiding complications.
In most cases, corticosteroid medications such as prednisone are the preferred method of treatment. They can be taken orally or applied to the skin. Corticosteroids lower the response of your immune system, which reduces the amount of inflammation-causing antibodies. Your doctor will likely start you on a high dose of corticosteroids and then slowly lower the amount over a few weeks.
Other Drug Therapies
If corticosteroids alone don’t improve your symptoms, your doctor might prescribe other medications to suppress your immune system.
These medications are used to reduce the side effects of corticosteroids. Drugs such as Azasan and methotrexate may be used if your case is advanced or if you have any complications.
Intravenous immunoglobulin (IVIG)
IVIG uses healthy antibodies to block the attacking antibodies you are producing that target your skin and muscles. IVIG consists of a mixture of antibodies that have been collected from thousands of healthy people who have donated their blood. These treatments don’t last very long, and it’s likely you’ll need a new infusion every six to eight weeks.
Tacrolimus is a drug given to transplant patients to prevent rejection of the new organ by suppressing the immune system. It comes in both pill and cream form.
Other Treatment Methods
Depending on your case, your doctor might suggest additional treatments such as:
- physical therapy that improves and preserves your muscle strength along with preventing loss of muscle tissue
- antimalarial medications for a persistent rash
- surgery to remove calcium deposits
- medications to help with pain
The muscle weakness and skin problems linked with the disease can cause a number of problems. Some common complications are:
- difficulty breathing
- lung infections
- problems swallowing
- weight loss