Cyanotic limb in a newborn: a peculiar presentation of septic hip.

A 12-day-old infant presented with marked cyanosis of the right lower limb, mimicking vascular compromise. Physical examination, plain radiography, and laboratory evidence of systemic infection suggested septic arthritis of the hip. Pyoarthrosis was verified by needle aspiration and open drainage. Streptococcus pneumoniae was isolated. A cyanotic limb may be an atypical presentation for septic arthritis in the newborn.