Hip pain in patient with Crohn's disease. Occult retroperitoneal abscess as cause.

A 20-year-old man with Crohn's disease was seen as an outpatient for pain in the left hip and gait disturbance. Initially, arthritis of the hip was suspected, because of the absence of fever or abdominal abnormalities. Two weeks later, fever, malaise, and pneumaturia developed and urine culture grew Escherichia coli. Laparotomy revealed a large occult retroperitoneal abscess on the left side, which had been irritating the psoas muscle. Surgical drainage effected complete recovery of hip function. The abscess in this patient had a very unusual presentation and was diagnosed chiefly through a high index of suspicion after a careful physical examination.