What is juvenile dermatomyositis (JDM)?
JDM is an autoimmune disease that affects muscle, skin and small blood vessels in children. The body’s immune system attacks its own healthy muscle, skin and blood vessel tissues because it mistakenly sees them as invaders. The primary symptoms are muscle weakness and skin rashes due to inflammation from an overactive immune system.
How common is juvenile dermatomyositis (JDM)?
JDM is a rare autoimmune disease with approximately 2-4 children per one million children being diagnosed each year in the United States. The disease presents more commonly in girls than boys and usually occurs between the ages of 2 and 15.
What causes juvenile dermatomyositis (JDM)?
The cause of JDM is not known. Researchers believe it may be a result of the body’s abnormal immune system response to environmental triggers (eg, a virus) in children with a genetic predisposition to having an overactive immune system. Even after the trigger is gone, the immune system continues to fight and ends up attacking the body itself.
What are the symptoms of juvenile dermatomyositis (JDM)?
The main symptoms of juvenile dermatomyositis are muscle weakness and skin rashes. This is caused by inflammation in the small blood vessels (vasculitis) in skin and muscle and also by inflammation of the muscle cells. Other symptoms may include:
- Violet-color and dusky red rash: on face, eyelids, cheeks, chest wall, knees or back of elbows. (This may be mistaken for eczema.)
- Raised bumps on knuckes
- Gradual muscle weakness (often in the neck, shoulders, trunk, back or hips)
- Difficulty with everyday activities, such as climbing stairs, standing up, riding a bicycle, getting dressed, lifting the head
- Frequently falling down
- Weak voice (dysphonia)
- Difficulty swallowing (dysphagia)
- Sore and swollen joints
- Severe abdominal pain (because of ulcers in the digestive system due to the vasculitis)
- Hardened lumps from deposits of calcium underneath the skin (calcinosis)
- Lung problems (because of inflammation and thickening of small airways in lungs)
Due to these symptoms, the child may not feel like participating in normal childhood activities. Sometimes the child may even be accused of being lazy.