Clinical Manifestations of Juvenile Rheumatoid Arthritis

Juvenile rheumatoid arthritis (JRA) is a common, rheumatic disease of children and a major cause of chronic disability. It is characterized by a synovitis of the peripheral joints manifesting in soft tissue swelling and effusion.

In the Classification Criteria of the American College of Rheumatology (ACR), JRA is regarded not as a single disease but as a category of diseases with three principal types of onset:

(1) oligoarthritis or pauciarticular disease,

(2) polyarthritis, and

(3) systemic-onset disease.

Initial symptoms may be subtle or acute, and often include morning stiffness and gelling, easy fatigability, particularly after school in the early afternoon, joint pain later in the day, and objective joint swelling. The involved joints are often warm, resist full range of motion, are painful on motion, but are not usually erythematous.

Oligoarthritis (pauciarticular disease) predominantly affects the joints of the lower extremities, such as the knees and ankles . Often, only a single joint is involved at onset. Isolated involvement of upper extremity large joints is not characteristic of this type of onset. Involvement of the hip is almost never a presenting sign of JRA. Hip disease may occur later, particularly in polyarticular JRA, and is often a component of a deteriorating functional course.

Polyarthritis (polyarticular disease) is generally characterized by involvement of both large and small joints of both upper and lower extremities . As many as 20–40 joints may be affected in the more severely involved child, although inflammation of only ?5 joints is required as a criterion for classification of this type of onset. Polyarticular disease may resemble the characteristic presentation of adult rheumatoid arthritis and the HLA profile is often similar. Rheumatoid nodules on the extensor surfaces of the elbows and over the Achilles tendons, while unusual, are associated with a more severe course. Micrognathia reflects chronic temporomandibular joint disease. Cervical spine involvement of the apophyseal joints  occurs frequently with a risk of atlantoaxial subluxation and potential neurologic sequelae.

Systemic-onset disease is characterized by arthritis and prominent visceral involvement that includes hepatosplenomegaly, lymphadenopathy, and serositis, such as a pericardial effusion. It is characterized by a quotidian fever with temperatures to ?39°C, sometimes followed by mildly hypothermic temperatures for ?2 wk. Each febrile episode is frequently accompanied by a characteristic faint, erythematous, macular rash; these evanescent salmon-colored lesions may be linear or circular, from 2–5 mm in size, and are often distributed in groups with a linear distribution most commonly over the trunk and proximal extremities . This rash is not pruritic. Its most diagnostic feature is its transient nature, with a group of lesions usually lasting <1 hr. The Koebner phenomenon, which is cutaneous hypersensitivity to superficial trauma resulting in a localized recurrence of the rash, is suggestive, but not diagnostic, of systemic-onset disease. Heat, such as a warm bath, also evokes a reappearance of the rash.