Heterotopic ossification of the quadratus lumborum muscle.

Heterotopic ossification is a benign process of mature laminar bone formation in the soft tissues. A synonymous term used to describe this pathology in muscle is myositis ossificans. The pathogenesis is unclear, but is likely multifactorial. The basic pathology is thought to be ectopic production of osseous tissue as part of a repair process in response to tissue injury. This report describes a case of heterotopic ossification of the quadratus lumborum muscle as an incidental finding. This case highlights that treatment is based on symptoms and conservative management might be appropriate for the asymptomatic patient.