Obturator externus pyomyositis.

Pyomyositis of the obturator externus muscle is a rare cause of limp and hip pain in children. The exact etiology of the condition remains poorly understood, although a mechanism of transient bacteremia in association with increased muscle susceptibility has been proposed. This case describes the course of a rather than 1 child from presentation to diagnosis and demonstrates the requirement for magnetic resonance imaging in establishing a diagnosis.