Psoas abscess with associated septic arthritis of the hip in infants.

We describe psoas abscess with concomitant septic hip arthritis in 2 infants, 3 and 7 months old. The common clinical features were a palpable mass in the inguinal region, irritable hip, and delayed treatment. The diagnosis of septic hip was delayed in one child, and they both had residual hip deformity at follow-up. It is possible that initial delay in diagnoses resulted in the concurrent pathologic condition because of spread of infection. These 2 cases demonstrate the first known reports of concurrent psoas abscess and septic hip arthritis in infancy. Magnetic resonance imaging is a valuable method to identify these concurrent pathologic conditions. A proposed etiologic mechanism is also discussed in the article.