Poststreptococcal reactive arthritis mimicking acute septic arthritis: a hospital-based study.

Poststreptococcal reactive arthritis (PSRA) is an inflammatory arthritis that follows group A streptococcal pharyngitis. The clinical presentation of PSRA can mimic acute septic arthritis. We present 12 children with PSRA seen between December 1991 and September 1993. Most children had only mild pharyngitis by history. The pattern of arthritis was variable and included migratory polyarthritis, additive polyarthritis, and monoarthritis, and was accompanied by fever in seven children. In four patients, the presentation of fever and acute onset of painful monoarthritis mimicked septic arthritis, and synovial fluid cultures were negative in all four cases. All 12 patients demonstrated an immune response to group A streptococcus. PSRA should be in the differential diagnosis of any child presenting with acute onset of painful arthritis, including those cases of presumed septic arthritis with negative synovial fluid cultures.