Piriformis muscle abscess associated with pyogenic sacroiliitis

Pyogenic sacroiliitis is a relatively rare cause of hip pai n and fever. Psoas muscle abscess complicating pyogenic sacroiliitis, has been reported in some cases; however, pir iformis muscle abscess causing sacroiliitis has never been described. We report a 14-year-old girl who developed a piriformis muscle abscess associated with pyogenic sacroiliitis due to met hicillin- sensitive Staphylococcus aureus.