Juvenile idiopathic arthritis in Child
The most widely adopted classification criteria for JIA is shown below, and it is based mostly on clinical presentation rather than disease pathophysiology. Attempts at incorporating biologic data into new classification criteria are underway, and may help to provide more homogeneous disease subsets in the future. Genetic factors are being investigated within subsets of these diseases.
- Oligoarthritis (fewer than 5 joints involved) – The most common type of JIA, seen in girls aged 2-4 years, it usually affects the lower extremities. This type of arthritis is often complicated by asymptomatic uveitis, a potentially sight-threatening condition; the presence of a positive ANA increases this risk.
- Rheumatoid factor (RF)-positive polyarthritis (5 or more joints involved) – Usually affects adolescent girls; presents with a symmetric arthritis of small joints (wrists and fingers) and a positive RF serology. This disease is the same as adult rheumatoid arthritis.
- RF-negative polyarthritis (5 or more joints involved) – A heterogeneous group; can have positive ANA and behave like oligoarthritis, or can resemble seronegative rheumatoid arthritis in adults.
- Psoriatic arthritis – Often affects children aged 2-4 and 9-11. It is diagnosed when arthritis is seen in patients with psoriasis, or if there is dactylitis (swelling of a finger), nail pits, or a first-degree family member with psoriasis. Patients with nail, scalp, and inverse (intertriginous) psoriatic skin disease have a higher risk of developing psoriatic arthritis.
- Enthesitis-related arthritis – Usually affects boys older than 6 years of age and is characterized by enthesitis, or inflammation of the entheses (the region where tendons and ligaments insert into bone), commonly at the Achilles tendon or plantar fascia. It is associated with HLA-B27 and is often called seronegative spondyloarthropathy.
- Systemic arthritis – This disorder is characterized by the presence of arthritis and quotidian fevers, usually occurring at night, as well as an evanescent salmon-colored rash and systemic features such as hepatosplenomegaly, lymphadenopathy, leukocytosis, and elevations in inflammatory markers (ESR, CRP). Not all features of the disorder will be present at disease onset. This disorder is thought to represent an autoinflammatory disease, in which the innate immune system creates uncontrolled systemic inflammation. The development of macrophage activation syndrome can be fatal.
- Undifferentiated arthritis – Patients not meeting inclusion criteria for any disease or who meet more than 1 set of criteria are classified in this category.
M08.00 – Unspecified juvenile rheumatoid arthritis of unspecified site
410795001 – Juvenile rheumatoid arthritis
- Psoriatic arthritis is included in classification criteria for JIA; see Synopsis.
- Septic arthritis – Fever, joint pain with erythema, and severely limited range of motion secondary to pain.
- Osteomyelitis – Usually affects children under the age of 5; associated with fever and pain, should be further evaluated with imaging.
- Lyme arthritis (see Lyme disease) – In endemic areas, it is a late manifestation of Lyme disease and usually presents with painless swelling of 1 knee.
- Systemic lupus erythematosus – Arthritis associated with other signs and symptoms of SLE.
- Malignancy – May present with an unusual pattern of joint involvement, systemic features, night-time pain, and low or inappropriately normal white blood cell and platelet counts despite the presence systemic inflammation.
- Trauma – Usually presents acutely.
- Acute rheumatic fever – Occurs 2-3 weeks after streptococcal infection. Children may develop a migratory polyarthritis, carditis, chorea, erythema marginatum, subcutaneous nodules, fever, elevated inflammatory markers, and heart block.
- Post-Streptococcus reactive arthritis – Occurs 1-2 weeks after a streptococcal infection; non-migratory arthritis; does not meet criteria for acute rheumatic fever.
- Reactive arthritis – Usually occurs several weeks after a genitourinary or gastrointestinal infection and primarily affects the lower extremities.
- Viral / post-viral arthritis – Parvovirus B19, rubella, hepatitis C virus, hepatitis B virus, or human immunodeficiency virus (HIV).
- Transient synovitis – Usually follows viral upper respiratory tract infection; occurs in boys ages 3-10 and manifests with sudden-onset hip pain and limp. Children usually appear well and lack high fevers.
- Immunoglobulin A vasculitis (formerly Henoch-Schönlein purpura) – Palpable purpura in dependent areas, abdominal pain, renal disease.
- Kawasaki disease – Young children, 2 years of age, with conjunctivitis, cervical lymphadenopathy, erythema of the lips and oral mucosa, extremity changes, rash.
- Serum sickness – Rash, fever 1-2 weeks after offending drug.
- Cryopyrin‐associated periodic syndromes (CAPS)