Section 17. Autoimmune Connective Tissue Diseases

Juvenile rheumatoid arthritis (JRA) is a generalized systemic disease of unknown etiology characterized by a transient macular, papular, or urticarial rash and ensuing fever, lymphadenopathy, hepatosplenomegaly (HSM), anemia, and arthralgia.

Insight

There are four classical evanescent eruptions: (1) urticaria, (2) erythema marginatum (of acute rheumatic fever), (3) the rash of Still disease, and (4) serum sickness.

Classification

JRA has three major types:

1. 1. Systemic onset (20%): Still’s disease, fevers, rash, lymphadenopathy (LAD), HSM, serositis, polyarthritis

   2. Polyarticular (20%): >five joints, hands, feet > knees/wrists/ankles

   3. Oligo-/Pauciarticular (60%): < four joints, knees > ankles

Synonyms Still’s disease, juvenile idiopathic arthritis, juvenile chronic arthritis.

Epidemiology

Age Peaks: 2 to 4 years, adolescence.

Gender Systemic JRA: M = F. Others: F > M, 2:1.

Prevalence 1/1000.

Genetics Polymorphisms for the genes encoding tumor necrosis factor-α (TNF-α), migratory inhibitory factor, interleukin-6 (IL-6), and tapasin (endoplasmic reticulum component involved in antigen presentation).

Etiology Unknown.

Pathophysiology

Cytokines TNF-α, migratory inhibitory factor, and IL-6 parallel the fever spikes, but the pathogenesis of JRA is still not understood. JRA tends to be precipitated by emotional, infectious, or surgical stress.

History

The onset of JRA may be sudden or insidious, depending on the age of the patient (the younger the patient, the more severe the systemic manifestations). Cutaneous eruptions occur in 90% of patients and may be the initial presentation. The rash of JRA is evanescent and can be macular or urticarial. Systemically, there may be associated fever, adenopathy, splenomegaly, anemia, and arthralgias.

Physical Examination

Skin Findings

Type Macules, papules, urticarial plaques (Fig. 17-1).

Size 2–6 mm to 8–9 cm.

Color Salmon pink to red, with a zone of pallor (Fig. 17-2).

Distribution Areas of trauma/heat: axilla, waist, olecranon process/ulnar forearm, dorsal hands, knees, ears, scapula, sacrum, buttocks, and heels.

Other Palms and soles: thenar and hypothenar eminences may be erythematous. Periungual telangiectases (5% of patients). Spindling fingers (50%, spindle-shaped deformity of fingers because proximal interphalangeal involvement > distal interphalangeal involvement).

General Findings

Fever >38.9°C

LAD, HSM

Musculoskeletal Arthralgias/arthritis: single joint (knees > ankles/hips > hands), symmetric polyarthritis joints, motion limitation (knees: 90%, fingers: 75%, ...