Define the term Juvenile Chronic Arthritis.
A collection of joint disorders characterised by arthritis that is:
- non-infective
- > 3 months duration
- inflammatory
- in children <16 years of age
Discuss the pathological features of JIA.
- primary synovial inflammation
- fibrosis and ankylosis
- flexion deformities are common
- retardation of growth & local bone deformities → is due to chronic inflammation and alteration in blood supply to eg growth plates
NB: cartilage erosion is as not marked as in RA → severe joint instability is uncommon
Briefly describe the clinical features of the following forms of JIA; in your answer, you must highlight the distinguishing features of each form of JIA:
a. Systemic JIA
• initially: episodes of fever/ macular rashes/malaise
o these episodes occurs daily
• the episodes last for a few hours during which the child appears quite ill.
o between episodes the child seems well
• +/- lymphadenopathy splenomegaly hepatomegaly
• joint swelling
o occurs weeks/months after onset
o usually resolves when the condition subsides
o may become progressive seronegative polyarthritis
b. Pauciarticular JIA
• no systemic illness • only a few joints are affected • presenting ssx: o swelling of medium sized joints (knee/ankle/elbow/wrist) o swelling of only a single joint o chronic iridocyclitis • remission occurs after a few years; the child may have permanent: o growth defects o sight problems o asymmetrical deformities
c. Polyarticular JIA
• polyarticular arthritis
o TMJ
o Cx Spine
o Hands / wrists
• Classic RA-like deformities usually absent
• the condition may however present as an RA-like condition with a positive RF, in which case it is described as “JUVENILE RA”.
Briefly discuss the main laboratory investigations which are employed in JIA. Comment on the typical findings for each investigation.
- ESR / CRP: incr. (systemic condition)
- WBC count: incr. (systemic condition)
- RF: +ve in Juvenile RA only
- HLAB27: +ve in Juvenile AS.
- Joint aspiration and synovial fluid examination will exclude infection/septic arthritis (comparatively non-developed immune system wrt adult Pt) and haemarthrosis (because of young age of Pt chance that haemophillia may not have been previously diagnosed)
Comment briefly on the diagnostic problems encountered in JIA.
• systemic JIA may resemble a viral infection
• systemic JIA with single joint involvement may be confused with:
o Reiter’s
o septic arthritis
o tuberculous arthritis (if manifestations are less acute)
• Always need to consider the possible presence of:
o leukemia
o rheumatic fever
o bleeding disorders (dt age of Pts)
List the main complications of JIA.
Ankylosis
o good function is the rule
o some loss of movement is common
Growth defects: o growth retardation o damage to growth plate eg. • external torsion of tibia • dysplasia of distal ulna • shortness of neck etc
Fractures:
o mainly in children < 5 years
o is due to osteoporosis (d/t incr. presence of inflammatory mediators around joints / bones → affects bone deposition) that may occur.
Iridocyclitis
o is common in pauciarticular disease
o if untreated, it may cause blindness
Amyloidosis
o occurs in long standing disease
o can be fatal
