Pediatric nontraumatic myositis ossificans of the neck.

Nontraumatic myositis ossificans circumscripta (MOC) is a rarely reported benign heterotopic ossification characterized by the aberrant formation of bone in extraskeletal soft tissues. Although a history of trauma can be elicited in 75% of MOC patients, the etiology is unclear in patients without inciting injury. MOC is associated with young male athletes, and is most often localized to the muscle groups of the extremities. Rare cases have been reported in children and adolescents of nontraumatic MOC in the neck. We present a 15-year-old adolescent with a rapidly growing, painful neck mass without traumatic stimulus.