Piriformis Muscle Abscess Associated With Pyogenic Sacroiliitis

Pyogenic sacroiliitis is a relatively rare cause of hip pain and fever. Psoas muscle abscess complicating pyogenic sacroiliitis, has been reported in some cases; however, piriformis 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 methicillin-sensitive Staphylococcus aureus.