Juvenile dermatomyositis (JDM) factsheet

Introduction

Juvenile dermatomyositis (JDM) is a disease that affects the small blood vessels in the muscles and skin. It is a rare but treatable autoimmune condition. 

Autoimmune conditions cause the immune system to get confused and attack its own body instead of fighting off illness and infections. 

JDM is usually seen in children between the ages of four and ten but can develop at any age. 

JDM cannot be caught from other people and is not passed down in families.

 Signs and symptoms

Symptoms of JDM can vary for each child but commonly include:

  • tiredness or fatigue – when your child is sleepier than usual, affecting their normal daily activities like walking, playing and sport
     
  • muscle pain and weakness – usually in the torso, abdomen, back and neck, your child may not be able to move or do their everyday activities without pain
     
  • breathing problems – weakness in your child’s airway muscles can make it difficult to swallow and breathe, and their voice may sound a bit different
     
  • muscle inflammation – where the muscles become short, tight, and swollen, making it difficult to straighten out their arms and legs
     
  • rashes on the face – usually causing swelling around the eyes, a purple-pink colour on the eyelids and red cheeks
     
  • rashes, sores, and thickened skin – showing up before pain, getting worse in the sunlight and usually on the knuckles, knees, and elbows
     
  • calcinosis – hard lumps full of calcium that build up under the skin and are difficult to treat
     
  • abdominal pain or stomach ache – sometimes affecting the bowels and causing hard poos that are difficult to pass.

Diagnosis

Your local doctor will refer your child to a specialist doctor called a rheumatologist for diagnosis and management of JDM. 

A rheumatologist looks after the joints and muscles. They will be able to diagnose JDM based on the results from tests, including:

  •  a physical check
  • blood tests to check the level of enzymes, substances made by muscles when they are damaged or inflamed
  • MRI scans to get a picture of the affected muscles
  • electromyography (EMG), a test that measures how your child’s muscle response when stimulated with a small needle
  • biopsy, where a small sample of your child’s muscle is taken and tested.

Your child’s doctor will let you know which tests are needed depending on symptoms. 

Treatment

JDM is an ongoing childhood condition that can be managed well with medications to control inflammation.  

Your child’s doctor will talk to you about different medications and treatments for JDM and which ones are most suitable.

 Management

Follow-up care

Treatment of JDM will usually improve the symptoms, and it may get better by the time your child is an adult.

Your child will have regular blood tests, and checkups with their treatment team as they grow.

School and everyday activities

Treatment for JDM aims to help your child return to normal activities like playing, sports, and school. 

Along with medication, your child will see a physiotherapist to exercise and strengthen affected muscles. 

Physiotherapists will develop a program to help your child regain movement and flexibility while reducing stiffness and pain. 

You can support your child at home by keeping up with physiotherapy exercises. 

Let school and other activities know about your child’s treatment so they can modify activities appropriately.

Last updated Wednesday 17th April 2024

Disclaimer

This factsheet is provided for general information only. It does not constitute health advice and should not be used to diagnose or treat any health condition.

Please consult with your doctor or other health professional to make sure this information is right for you and/or your child.

The Sydney Children’s Hospitals Network does not accept responsibility for inaccuracies or omissions, the interpretation of the information, or for success or appropriateness of any treatment described in the factsheet.

© Sydney Children’s Hospitals Network 2024


This factsheet was produced with support from John Hunter Children's Hospital.