Patient education: Dermatomyositis (The Basics)

What is dermatomyositis? — Dermatomyositis, or "DM," is a condition that causes muscle weakness and skin rashes. In people with DM, the muscles and skin get inflamed. A small number of people also develop lung problems. Doctors don't know what causes DM.

DM is more common in adults, but it can also happen in children.

What are the symptoms of DM? — DM causes:

●Muscle weakness – The weakness affects both sides of the body and usually happens slowly over time. It involves muscles closest to the trunk of the body, such as those in the neck, shoulders, hips, and thighs. Depending on the muscles involved, people with DM can have trouble climbing stairs, lifting things overhead, or swallowing.

●Skin rashes – DM causes different kinds of skin rashes on different parts of the body. The rashes are usually very itchy, sometimes scaly, and sometimes red. Sunlight usually makes the rashes worse. People can get rashes on their:

•Fingers, including on the backs of the finger joints and around the fingernails

•Elbows and knees

•Upper eyelids

•Neck, upper chest, or upper back

•Scalp

●"Interstitial lung disease" – About 1 in 10 people with DM develop this. Interstitial lung disease can cause inflammation and sometimes scarring in the lungs. This makes it hard for oxygen to get from the air into the lungs, which can make it hard to breathe.

Is there a test for DM? — Yes. Your doctor or nurse will order 1 or more of the following tests:

●Blood tests – These include tests to look for muscle irritation and inflammation, and to check how your immune system is working. (The immune system is the body's infection-fighting system.)

●Electromyography ("EMG") – This test shows whether your muscles are responding to the nerves' electrical signals in the correct way.

●Muscle biopsy – For this test, the doctor takes a small sample of tissue from a muscle that is weak. Then, another doctor looks at the sample under a microscope.

●Skin biopsy – For this test, the doctor takes a small sample of skin from your skin rash. Then, another doctor looks at the sample under a microscope.

●An imaging test called an MRI scan – Imaging tests create pictures of the inside of the body. This can show changes in the muscle.

How is DM treated? — Treatment for DM involves different parts.

The main treatment for DM includes medicines called steroids. Steroids help reduce inflammation.

People with DM usually need to take steroids for a long time. But steroids have side effects of their own. They can make your bones weak and increase your chances of getting an infection. To avoid these side effects as much as possible, your doctor will slowly lower (or "taper") your dose over time.

Your doctor will also treat you with other medicines. These include medicines that calm your immune system.

Your doctor might also give you medicines to help your skin symptoms and itching. Some of these medicines go on the skin. Others come as a pill.

Other treatment for DM involves keeping your body as strong as possible and preventing further problems. This usually includes:

●Working with a physical therapist (exercise expert) to learn exercises to strengthen your muscles

●Avoiding sunlight by wearing sunscreen, wide-brimmed hats, long-sleeved shirts, and long pants

●Changing what and how you eat if you have trouble swallowing or choke easily on your food

●Taking medicines to prevent side effects from the steroids

What if I want to get pregnant? — If you want to get pregnant, talk with your doctor or nurse. They will work with you to get your DM under control before you get pregnant. They will also make sure that your medicines are safe to take during pregnancy.

What will my life be like? — It depends on your individual situation. Some people with DM have only mild symptoms. But many people have more bothersome symptoms that last years.

DM can be associated with certain types of cancer in adults. Your doctor might recommend certain tests. Your doctor might also do additional testing to make sure that you don't have heart problems caused by DM.

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