Case report of a 13-year-old boy with an obturator internus abscess and a need for re-imaging in this condition

Abstract

Introduction: Obturator internus pyomyositis is a rare entity, which is becoming more common in temperate regions including the United Kingdom. Typically, it presents with a triad of hip pain, fever and an inability to weight-bear on the affected side mimicking other hip pathologies such as septic arthritis. Conclusive diagnosis relies on imaging modalities such as computed tomography (CT) scan and magnetic resonance imaging (MRI) scan. Since the first described case in literature in 1992, it has been common practice to treat the condition with intravenous antibiotics and incision and drainage if required, however, the most appropriate follow-up of this condition post-treatment has not been clearly defined. In particular, the role of post-treatment imaging to monitor the resolution of the abscess is not yet known. Case Report: We present a case of a 13-year-old boy with an obturator internus abscess, whose diagnosis proved to be challenging due to an initial negative hip radiograph and ultrasound. Magnetic resonance imaging (MRI) played a key role in reaching the correct diagnosis. Followup imaging using MRI scan proved to be essential in the successful management of this case.