Idiopathic arthritis

Question 1

Define juvenile idiopathic arthritis (JIA) [1]

Answer 1

Juvenile idiopathic arthritis (JIA) refers to a condition affecting children and adolescents where autoimmune inflammation occurs in the joints. It is diagnosed where there is arthritis without any other cause, lasting more than 6 weeks in a patient under the age of 16.

Question 2

What are the 5 types of JIA? [5]

Answer 2

Systemic JIA - aka Still’s disease.
Polyarticular JIA
Oligoarticular JIA
Enthesitis related arthritis
Juvenile psoriatic arthritis

Question 3

Describe the clinical presentation of Still’s disease / systemic JIA [+]

Answer 3

Systemic illness that can occur throughout childhood in boys and girls. It is an idiopathic inflammatory condition. Usually has:
* Subtle salmon-pink rash
* High swinging fevers
* Enlarged lymph nodes
* Weight loss
* Joint inflammation and pain
* Splenomegaly
* Muscle pain
* Pleuritis and pericarditis

Question 4

TOM TIP: Think of Still’s disease (systemic JIA) when a patient presents with a salmon-pink rash, fevers and joint pain.

In children that have fevers for more than 5 days, the key non-infective differentials to remember are [4]

Answer 4

Kawasaki disease, Still’s disease, rheumatic fever and leukaemia.

Question 5

How do you investigate for Still’s disease? [4]

Answer 5

Clinical picture

Serology:
- ANA and RF negative
- Raised CRP; ESR; platelets and ferritin

Question 6

Describe a key complication of Still’s disease / systemic JIA? [1]

How does it present? [6]

Answer 6

Macrophage activation syndrome (MAS):
- massive inflammatory response

Presentation:
- DIC
- Anaemia
- Thrombocytopenia
- Bleeding
- Non-blanching rash
- Low ESR

Question 7

Describe the pattern of pyrexia experienced in Still’s disease in adults [1]

Answer 7

typically rises in the late afternoon/early evening in a daily pattern and accompanies a worsening of joint symptoms and rash

Question 8

Tx for Still’s disease (in adults) [2]

Answer 8

NSAIDs
* should be used first-line to manage fever, joint pain and serositis
* they should be trialled for at least a week before steroids are added.

steroids
* may control symptoms but won’t improve prognosis

Question 9

Describe the presentation of polyarticular JIA [2]

Answer 9

• idiopathic inflammatory arthritis in 5 joints or more
• symmetrical arthritis
• mild systemic symtpoms

NB - think of it like a seronegative juvinilie RA

Question 10

Describe the presentation oligoarticular JIA [4]

Answer 10

• It involves 4 joints or less.
• Usually it only affects a single joint, which is described as a monoarthritis - often knee or ankle
• Classically associated with anterior uveitis - refer to an opthamologist
• ANA positive

Question 11

How can you think of Enthesitis-Related Arthritis? [1]

Answer 11

A paediatric version of the seronegative spondyloarthropathy group of conditions that affect adults. These conditions are ankylosing spondylitis, psoriatic arthritis, reactive arthritis and inflammatory bowel disease-related arthritis.

The majority of patients with enthesitis-related arthritis have the HLA B27 gene.

Question 12

Describe the managment of juvenile idiopathic arthrits

Answer 12

NSAIDs, such as ibuprofen
Steroids, either oral, intramuscular or intra-artricular in oligoarthritis
DMARDs, such as methotrexate, sulfasalazine and leflunomide
Biologic therapy, such as the tumour necrosis factor inhibitors etanercept, infliximab and adalimumab