Prolonged fevers of unknown origin in children: patterns of presentation and outcome

To review the presentation, clinical characteristics, and outcome of children with prolonged fevers of unknown origin who are referred for pediatric rheumatologic evaluation.

We used a retrospective review of the charts of the 40 children (23 boys and 17 girls, aged 9 months to 14.6 years) with fevers persisting longer than 1 month who were referred to the Pediatric Rheumatology Clinic between 1984 and 1994, in whom evaluation did not result in diagnosis. Follow-up with children's families, pediatricians, or both was done by telephone.

Of the 40 children, 29 had periodic fevers, and 11 had daily fevers without pattern. Patients with periodic fever were younger at onset, had longer duration of symptoms before referral, and higher maximum temperatures. The two groups did not differ in frequency of associated symptoms or signs. At follow-up (mean 60.5 +/- 5 months, n = 37), 10 children with daily fevers (within 24 months) and 23 children with periodic fevers (within 48 months) had completely recovered; three patients continue to have periodic fevers. In patients with daily fevers one had Crohn disease (7 months after initial evaluation) and another had uveitis (4 years after evaluation). One patient with periodic fevers had inflammatory bowel disease 3.5 years after the onset of fevers. Petit mal seizures developed in one patient with periodic fever, and another had mitochondrial encephalopathy. Four children with periodic fevers have attention-deficit hyperactivity disorder, and two have developmental delays.

Fevers without an obvious source usually have a benign outcome, although patients should be monitored for changes in symptoms. Of the children with periodic fevers, 29% were later found to have neurologic problems; the relation to the previous fevers is uncertain.