Dermatomyositis (dur-muh-toe-my-uh-SY-tis) is an uncommon inflammatory disease marked by muscle weakness and a distinctive skin rash.

Dermatomyositis affects adults and children alike. In adults, dermatomyositis usually occurs from the late 40s to early 60s. In children, the disease most often appears between 5 and 15 years of age. Dermatomyositis affects more females than males.

There's no cure for dermatomyositis, but periods of remission — when symptoms improve spontaneously — may occur. Treatment can clear the skin rash and help you regain muscle strength and function.

The most common signs and symptoms of dermatomyositis include:

  • Skin changes. A violet-colored or dusky red rash develops, most commonly on your face and eyelids and on areas around your nails, knuckles, elbows, knees, chest and back. The rash, which can be patchy with bluish-purple discolorations, is often the first sign of dermatomyositis.
  • Muscle weakness. Progressive muscle weakness involves the muscles closest to the trunk, such as those in your hips, thighs, shoulders, upper arms and neck. The weakness affects both the left and right sides of your body, and tends to gradually worsen.

When to see a doctor

Seek medical attention if you develop muscle weakness or an unexplained rash.

The exact cause of dermatomyositis is unknown, but the disease shares many characteristics with autoimmune disorders, in which your immune system mistakenly attacks your own body tissues.

Small blood vessels in muscular tissue are particularly affected in dermatomyositis. Inflammatory cells surround the blood vessels and eventually lead to degeneration of muscle fibers.

Possible complications of dermatomyositis include:

  • Difficulty swallowing. If the muscles in your esophagus are affected, you may have problems swallowing (dysphagia), which in turn may cause weight loss and malnutrition.
  • Aspiration pneumonia. Difficulty swallowing may also cause you to breathe food or liquids, including saliva, into your lungs (aspiration), which can lead to pneumonia.
  • Breathing problems. If your chest muscles are affected by the disease, you may experience breathing problems, such as shortness of breath.
  • Calcium deposits. Deposits of calcium can occur in your muscles, skin and connective tissues (calcinosis) as the disease progresses. These deposits develop earlier and are more common in children with dermatomyositis.

Associated conditions

Dermatomyositis may cause other conditions or put you at higher risk of developing them. These conditions include:

  • Raynaud's phenomenon. This is a condition in which your fingers, toes, cheeks, nose and ears turn pale when exposed to cold temperatures.
  • Other connective tissue diseases. Other conditions, such as lupus, rheumatoid arthritis, scleroderma and Sjogren's syndrome, can occur in combination with dermatomyositis.
  • Cardiovascular disease. Dermatomyositis may cause the muscular walls of your heart to become inflamed (myocarditis). In a small number of people who have dermatomyositis, congestive heart failure and heart arrhythmias may develop.
  • Lung disease. A condition called interstitial lung disease may occur with dermatomyositis. Interstitial lung disease refers to a group of disorders that cause scarring (fibrosis) of lung tissue, making the lungs stiff and inelastic. Signs and symptoms include a dry cough and shortness of breath.
  • Cancer. Dermatomyositis in adults has been linked to an increased likelihood of developing cancer, particularly of the cervix, lungs, pancreas, breasts, ovaries and gastrointestinal tract. Risk of cancer increases with age, although it appears to level off three years or so after a diagnosis of dermatomyositis. The diagnosis of cancer may also happen before you develop dermatomyositis.

You'll probably first bring your symptoms to the attention of your family doctor. He or she might refer you to a doctor who specializes in the treatment of arthritis and other diseases of the joints, muscles and bone (rheumatologist) or to a doctor who specializes in disorders of the nervous system (neurologist).

What you can do

When you go in to see your doctor, be sure to have a record of your symptoms. Although it may be difficult to pinpoint when symptoms started, try to estimate when your symptoms first started and which parts of your body have been affected. You may want to write a list that includes:

  • Detailed descriptions of your symptoms
  • Information about medical problems you've had
  • Information about the medical problems of your parents or siblings
  • All the medications and dietary supplements you take
  • Questions you want to ask the doctor

Prepare a list of questions ahead of time to help make the most of your limited time with your doctor. For dermatomyositis, some basic questions to ask your doctor include:

  • What is likely causing my symptoms?
  • Are there other possible causes for my symptoms?
  • Are my symptoms likely to change over time?
  • What kind of tests might I need? Are any special preparations required?
  • Are treatments available for my condition? What treatments do you recommend?
  • I have other medical conditions. How can I best manage them together?
  • Do you have any brochures or other printed material that I can take with me? What websites do you recommend?

In addition to the questions that you've prepared in advance, don't hesitate to ask your doctor questions during your appointment if you think of something new.

What to expect from your doctor

Your doctor will likely ask you several questions, such as:

  • When did you first notice your symptoms?
  • Did your condition develop gradually or did it come on suddenly?
  • Are you easily fatigued during waking hours?
  • What other symptoms are you experiencing?
  • Does your condition limit your activities?
  • Has anyone in your family ever been diagnosed with a disease or condition that affects the muscles?
  • Are you currently taking any medications or dietary supplements?
  • What, if anything, seems to improve your symptoms?
  • What, if anything, appears to worsen your symptoms?

If your doctor suspects you have dermatomyositis, he or she might suggest some of the following tests:

  • Blood analysis. A blood test will let your doctor know if you have elevated levels of muscle enzymes, such as creatine kinase (CK) and aldolase. Increased CK and aldolase levels can indicate muscle damage. A blood test can also detect specific autoantibodies associated with different symptoms of dermatomyositis, which can help in determining the best medication and treatment.
  • Chest X-ray. This simple test can check for signs of the type of lung damage that sometimes occurs with dermatomyositis.
  • Electromyography. A doctor with specialized training inserts a thin needle electrode through the skin into the muscle to be tested. Electrical activity is measured as you relax or tighten the muscle, and changes in the pattern of electrical activity can confirm a muscle disease. The doctor can determine the distribution of the disease by testing different muscles.
  • Magnetic resonance imaging (MRI). A scanner creates cross-sectional images of your muscles from data generated by a powerful magnetic field and radio waves. Unlike a muscle biopsy, an MRI can assess inflammation over a large area of muscle.
  • Skin or muscle biopsy. A small piece of skin or muscle is removed for laboratory analysis. A skin sample can confirm the diagnosis of dermatomyositis and rule out other disorders, such as lupus. A muscle biopsy may reveal inflammation in your muscles or other problems, like damage or infection. If the skin biopsy confirms the diagnosis, a muscle biopsy may not be necessary.

There's no cure for dermatomyositis, but treatment can improve your skin and your muscle strength and function. The earlier treatment is started in the course of dermatomyositis, the more effective it is — leading to fewer complications.

However, as with many conditions, no single approach is best; your doctor will tailor your treatment strategy based on your symptoms and how well they respond to therapy.

Medications

The most commonly used medications to treat dermatomyositis include:

  • Corticosteroids. Drugs such as prednisone can be very effective in controlling dermatomyositis symptoms. But prolonged use of these drugs can have serious and wide-ranging side effects, which is why your doctor may gradually taper the dose of medication down to lower levels.
  • Corticosteroid-sparing agents. When used in combination with a corticosteroid, these drugs can decrease the dose and potential side effects of the corticosteroid. The two most common medications used for dermatomyositis are azathioprine (Azasan, Imuran) and methotrexate (Trexall).
  • Rituximab (Rituxan). More commonly used to treat rheumatoid arthritis, rituximab is an option if initial therapies don't adequately control your dermatomyositis symptoms.
  • Antimalarial medications. For a persistent rash, your doctor may prescribe an antimalarial medication, such as hydroxychloroquine (Plaquenil).

Therapy

Depending on the severity of your symptoms, your doctor might suggest:

  • Physical therapy. A physical therapist can show you exercises to maintain and improve your strength and flexibility and advise an appropriate level of activity.
  • Speech therapy. If your swallowing muscles are weakened by dermatomyositis, speech therapy can help you learn how to compensate for those changes.
  • Dietetic assessment. Later in the course of dermatomyositis, chewing and swallowing can become more difficult. A registered dietitian can teach you how to prepare easy-to-eat foods.

Surgical and other procedures

  • Intravenous immunoglobulin (IVIg). IVIg is a purified blood product that contains healthy antibodies from thousands of blood donors. These healthy antibodies can block the damaging antibodies that attack muscle and skin in dermatomyositis. Given as an infusion through a vein, IVIg treatments are expensive and may need to be repeated regularly for the effects to continue.
  • Surgery. Surgery may be an option to remove painful calcium deposits and prevent recurrent skin infections.

With dermatomyositis, areas affected by your rash are more sensitive to the sun. As a precaution, wear protective clothing or high-protection sunscreen when you go outside.

Living with a chronic autoimmune disease can make you wonder at times whether you're up to the challenge. To help you cope, try supplementing your medical care with the following suggestions:

  • Know your illness. Read all you can about dermatomyositis and other muscle and autoimmune disorders. Talk to other people who have a similar condition. Don't be afraid to ask your doctor any questions that you may have concerning your illness, diagnosis or treatment plan.
  • Be a part of your medical team. Consider yourself, your doctor and any other medical experts involved as a united front in the fight against your disease. Following the treatment plan you agreed to is vital. Keep your doctor updated on any new signs or symptoms you may experience.
  • Get active. Maintaining an exercise routine can help you maintain and build your muscle strength. Just be sure that you get a detailed plan and recommendations from your doctor or physical therapist before starting an exercise program.
  • Rest when you're tired. Don't wait until you're exhausted. This will only set you back further as your body tries to recuperate. Learning to pace yourself can help you maintain a consistent level of energy, accomplish just as much and feel better emotionally.
  • Acknowledge your emotions. Denial, anger and frustration are normal feelings when you must deal with an illness. Things don't seem normal or fair and likely seem out of your control. Feelings of fear and isolation are common, so stay close to your family and friends. Try to maintain your daily routine as best you can and don't neglect doing those things you enjoy. Many people find support groups to be a helpful resource.
Jun. 17, 2014