The sore psoas: a difficult diagnosis in childhood.

Nontuberculous psoas abscess is an unusual disease of childhood. The symptoms closely mimic those of other disorders and delay of treatment is commonplace. Eight children (age range 1.5-12 yr) have been treated for psoas abscess. Each presented with a history of fever (38-40 degrees C) and pain. The pain was localized to the hip (3-right, 4-left) and aggravated by ambulation in 7 cases. In 6 children, there was associated lower abdominal tenderness and flexion of the involved hip at rest with resistance to extension. Only 1 child was correctly suspected of having a psoas abscess. Delay in appropriate therapy averaged 5 days (range 1-20 days). Five children underwent joint aspiration and an additional 3 underwent abdominal exploration prior to diagnosis. Surgical drainage was subsequently performed in each case. A retroperitoneal approach, either flank or inguinal, was employed. Staphylococcus aureus was isolated from all cultures. Primary psoas abscess is seldom included in the differential diagnosis of septic lower abdominal and/or lower extremity pain. It should, however, be considered, particularly in the child with classic findings of psoas irritation.