Pediatric emergency medicine trisk 1167 1167

TABLE 60.5
FEVER AND JOINT PAIN
Usually febrile at presentation
Septic arthritis (bacterial)
Osteomyelitis
Gonococcal arthritis
Acute rheumatic fever
Juvenile idiopathic arthritis (systemic onset subcategory)
Subacute bacterial endocarditis
Serum sickness
Kawasaki disease
May or may not be febrile at presentation
Leukemia
Mycobacterial arthritis
Postinfectious (reactive) arthritis
Lyme disease
Systemic lupus erythematosus
Inflammatory bowel disease
Joint involvement with Lyme disease has two distinct patterns. In early
localized or disseminated disease, the child may develop episodic migratory
polyarthritis, affecting mainly large joints. However, more typically at this stage,
the child has polyarthralgia without signs of joint inflammation. Weeks to months
(mean 4 to 6 weeks) after the tick bite, half of untreated children develop a
monoarthritis, usually of the knee. The joint is significantly swollen but only
mildly painful, and patients are usually afebrile at this stage and without a history
of trauma. A recent study of children in a Lyme-endemic area found that an
absolute neutrophil count <10 × 103 cells/mm3 and an ESR <40 mm/hr helped
distinguish Lyme arthritis from septic arthritis, although others have shown
significant overlap in these labs across the two etiologies of arthritis.
Extremely painful, migratory joint inflammation involving multiple joints in a
child with recent evidence of a group A streptococcal infection should raise the

concern for acute rheumatic fever. Evidence of carditis, erythema marginatum,
subcutaneous nodules, or a positive serology for antistreptococcal antibodies
supports the diagnosis. The presence of diffuse urticaria and angioedema
accompanying arthralgia or arthritis, especially 3 to 10 days after initiation of an