Primary obturator internus and obturator externus pyomyositis.

Background: Pyomyositis is a rare condition in immune competent patients and is usually seen in tropical countries. Pyomyositis of obturator muscles in particular is an extremely rare condition, which causes hip pain and mimics septic arthritis.

Case Report: This is a case report of a 9-year-old boy without an underlying disease or a compromised immune system, who presented with knee pain that progressed to hip pain and inability to bear weight. He was diagnosed initially with septic arthritis of the hip and underwent unnecessary hip exploration surgery. Magnetic resonance imaging scan was performed postoperatively and showed pyomyositis of obturator internus and obturator externus muscles. He was managed medically and had a good outcome.

Conclusions: A greater awareness of this emergency condition is necessary to prevent misdiagnosis, unnecessary surgical intervention, and to avoid the devastating possible complications of delayed diagnosis.