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Understanding Rheumatic Diseases

Clear, trusted information for families, youth and healthcare professionals

Pediatric rheumatic diseases can be complex and often unfamiliar at first. Whether you’re a parent, caregiver, healthcare provider, researcher, or student, understanding these conditions is essential to supporting care, decision-making, and long-term outcomes.

This section contains clear, practical information to help you understand juvenile arthritis and related conditions.

Start with the basics, then explore specific conditions and topics as you need.

What is JIA?

Juvenile Idiopathic Arthritis (JIA) – addressing the most common type of rheumatic disease in children.

Juvenile Idiopathic Arthritis (JIA) is the most common type of rheumatic disease in children. It refers to a group of autoimmune and inflammatory conditions that affect the joints and, in some cases, other parts of the body.

“Idiopathic” means the exact cause is unknown. What is known is that JIA occurs when the immune system mistakenly attacks healthy tissue, leading to inflammation, pain, stiffness, and swelling.

JIA can vary widely from child to child. Some experience mild symptoms that are well managed with treatment, while others may require ongoing care to control inflammation and prevent long-term joint damage.

Early diagnosis and treatment are important to help children stay active, manage symptoms, and maintain joint health.

Hear it from the kids

In Canada, JIA affects 1 in 1,000 kids.Juvenile Idiopathic Arthritis (JIA) – addressing the most common type of rheumatic disease in children.

That’s over 10,000 kids in Canada alone living with Juvenile Idiopathic Arthritis. Check out the video below to learn more about what JIA is, directly from kids living with it.

Types of JIA

JIA is not a single condition — it includes several subtypes.
Each type of JIA presents differently, with variations in how many joints are affected, the presence of systemic symptoms, and how the disease progresses. Understanding the subtype can help guide treatment and set expectations.

Oligoarticular JIA

Affects four or fewer joints, often the knees or ankles. This is the most common type and may be associated with eye inflammation (uveitis).

Polyarticular JIA

Affects five or more joints and can involve both small and large joints. It may resemble adult rheumatoid arthritis.

Systemic JIA

Involves joint inflammation along with systemic symptoms such as fever, rash, and fatigue.

Enthesitis-Related JIA

Affects areas where tendons attach to bones (entheses), often involving the lower limbs and spine.

Psoriatic JIA

Associated with psoriasis. May include joint inflammation along with skin and nail changes.

Undifferentiated JIA

Cases that don’t fit neatly into one category or show features of multiple subtypes.

RF-Positive Polyarticular JIA

A less common form of polyarticular JIA that is more similar to adult rheumatoid arthritis and may be more persistent.

JIA 101

In Canada, JIA affects 1 in 1,000 kids.

Parent speaker, Jennifer O’Shea and Dr. Roberta Berard, share information on the different subtypes of JIA, the difference between pain and a flare, and emerging research insights. Plus, answers to your questions regarding medications, treatment paths and remission.

Uveitis

Regular eye screening is an important part of treatment.

Uveitis is an inflammatory eye condition that can occur alongside juvenile idiopathic arthritis (JIA) and other childhood rheumatic diseases. Because symptoms are not always visible, regular eye screening is an important part of early detection, treatment, and ongoing care.

Learning about uveitis can help families recognize symptoms, understand treatment options, and support long-term eye health.

Learn more about Uveitis

Related Rheumatic
Conditions

Other conditions that impact different parts of the body.
In addition to JIA, other rheumatic conditions can affect children and youth. While they may share similarities, they can impact different parts of the body and require different approaches to care.

Lupus (SLE)

An autoimmune disease that can affect the skin, joints, kidneys and other organs in the body.

Vasculitis

A group of diseases characterized by inflammation of blood vessels, which causes them to thicken, weaken, narrow, or scar.

CRMO (Chronic Recurrent Multifocal Osteomyelitis)

A rare autoimmune disease causing chronic bone inflammation leading to bone lesions, pain, and potential swelling, often in legs, ankles, or jaws. 

Juvenile Dermatomyositis

A systemic inflammation of blood vessels, primarily affecting skin and muscles.

Scleroderma 

An autoimmune rheumatic disease characterized by the overproduction of collagen, causing hardening, thickening, and tightening of the skin and connective tissues.

Fever Syndrome

A group of conditions that cause recurring episodes of fever and inflammation without infection. These episodes may include symptoms like rash, joint pain, or fatigue.

Autoimmune vs.
Autoinflammatory

They both work in different ways and affect children differently.

Some pediatric rheumatic diseases are considered autoimmune conditions, while others are classified as autoinflammatory conditions. Although both involve the immune system causing inflammation in the body, they work in different ways and can affect children differently.

Understanding these differences can help families better understand symptoms, treatment approaches, and why certain conditions may behave differently from one another. It also helps explain why some diseases involve recurring fevers and widespread inflammation, while others primarily affect joints, skin, muscles, or organs.

Autoimmune Conditions

The immune system mistakenly attacks healthy tissues in the body.

These conditions often involve:

  • Joint inflammation
  • Fatigue
  • Skin or organ involvement
  • Ongoing immune system activity

Examples may include:

  • Lupus (SLE)
  • Some forms of JIA
  • Scleroderma

Autoinflammatory Conditions

The body’s innate immune system becomes overactive, leading to episodes of inflammation without infection.

These conditions may involve:

  • Recurring fevers
  • Rashes
  • Joint or muscle pain
  • Sudden inflammatory flare-ups

Examples may include:

  • Systemic JIA
  • Fever syndromes
  • CRMO

While these conditions differ in how the immune system behaves, both can cause significant inflammation and require specialized care, monitoring, and treatment.

Why understanding a child’s diagnosis matters

Taking time to understand your child’s condition helps you ask better questions, make informed decisions, and feel more confident in managing care.

It also helps children and youth better understand their own health as they grow — an important part of building independence over time.

Explore Related Topics

Explore key topics to better understand treatment, manage symptoms, and support your child’s overall wellbeing.

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Confidence through understanding

Cassie + Friends is here to support you — every step of the way.

While these conditions can feel complex at first, knowledge builds confidence. With the right information and support, families and young people can better navigate care and move forward with clarity.