Juvenile Dermatomyositis

What is juvenile dermatomyositis?

Juvenile dermatomyositis (JDM) is an autoimmune disease that causes inflammation of the muscles (myositis), skin, and blood vessels in children. In autoimmune diseases, the immune system mistakenly attacks healthy tissue and cells. For children with JDM, this results in muscle weakness and skin rashes. In severe cases, JDM can affect systems of the body such as the digestive tract, heart, and lungs.

JDM is rare in children. Those who do develop JDM are most often between five and 10 years of age, and the condition is more common in girls.

Both JDM and the less common juvenile polymyositis are forms of the autoimmune inflammatory muscle disorder, myositis.

What are the symptoms of juvenile dermatomyositis?

The most common symptoms of JDM are:

• Rash: A violet or dark red rash on the face and over the knuckles, knees, and elbows
• Muscle weakness: A gradually progressing muscle weakness that occurs in the muscles of the hips, thighs, shoulders, upper arms, and neck. It affects both sides of the body at the same time and can make simple movements difficult, such as getting up out of a chair or out of bed.

A more severe form of this condition may cause:

• Shortness of breath
• Difficulty swallowing
• Voice changes
• Calcium deposits in the muscles
• Fever
• Weight loss

How is juvenile dermatomyositis diagnosed?

If you or your pediatrician suspect JDM, your child will be referred to a pediatric rheumatologist, who will conduct a full medical exam and schedule some tests. Tests used to diagnose JDM include:

• Blood and urine tests check for elevated muscle-related enzymes.
• Magnetic resonance imaging (MRI) gives a view of the muscles that can show inflammation or can guide a muscle biopsy.
• Muscle biopsy allows for a close look of muscle tissue under a microscope, which can indicate the extent of tissue and muscle damage due to inflammation and distinguish JDM from other muscle-related diseases.
• Nalifold capillaroscopy uses a magnifying tool to look at the blood vessels around the nails, which are commonly swollen in patients with active JDM.  

How is juvenile dermatomyositis treated?

Juvenile dermatomyositis is treated primarily with medication and physical therapy. Specialists in our Pediatric Rheumatology Program will work with you to create the right treatment plan for your child.

Medications that we may prescribe to treat JDM include corticosteroids, methotrexate, mycophenolate, rituximab, and intravenous immune globulin.

Physical therapy and physical activity is essential for children with this condition, to maintain and increase muscle strength and flexibility.

We will also recommend avoiding sun exposure to help control the rash. Sunscreen and protective clothing are recommended.

Muscle weakness due to JDM can affect chewing and swallowing. Your child may be scheduled for appointments with a dietician to discuss healthy, safe eating.