What is juvenile myositis?
[JOO veh nil mie oh SIE tis]

Juvenile myositis, or JM, is sometimes called other names-juvenile dermatomyositis (JDM) or juvenile polymyositis (JPM).

JM is called an autoimmune (AHT oh i MYOON) disease. Your body has an immune system that fights off bad things, like colds and flu, that are not supposed to be in your body. In autoimmune diseases, like JM, your immune system keeps fighting, even though the bad things are not in your body anymore. So your immune system makes a mistake and ends up fighting your healthy muscles and skin. This makes your muscles feel weak, and sometimes they hurt. Some children also have a skin rash.

Nobody knows what causes JM, but you didn't "catch" it from anyone and your friends and family can't "catch" it from you. There are two main types of juvenile myositis-dermatomyositis and polymyositis. Most children who have myositis have dermatomyositis, or JDM.

How will JM make me feel?

JM makes your muscles weak and sore. You may have trouble standing up from a chair or walking up steps; reaching up to comb or wash your hair; or lifting your head. You might feel tired more often than you used to. Your skin may have a purple-red color or look puffy. You may also itch from the rash, and you have to be careful in the sun so your rash doesn't get worse.

With juvenile polymyositis, or JPM, you won't have the rash but your muscles will still weak and sore.

What will it be like to go to the doctor?

When you go to see doctors, they will ask you questions and do some special tests to see how you are doing and what they can do to make you feel better. The doctors test your blood and see how strong your muscles are. They look at your rash if you have one to see if it's getting any better or if there's something else they need to do to make it better.

Doctors may have to do other tests using equipment that looks like a big camera taking pictures of your muscles. This lets them see what's going on.

Updated March 2007