Juvenile Dermatomyositis (JDM)

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.

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.

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. 

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.