Sternomastoid tumor of infancy.

Sternomastoid tumor of infancy (SMTI) is the most common cause of neck mass in the perinatal period. We present seven children with this disorder, six studied prospectively. Ages at presentation ranged from 1 week to 4 weeks. Five had a history of birth trauma. Torticollis with facial asymmetry was seen in two. In six the diagnosis of SMTI was made clinically, and these patients were managed conservatively with massage and controlled stretching of the neck. Resolution of the neck mass, the torticollis, and the facial asymmetry occurred in all patients. Pathologic and radiographic findings are presented. We conclude that careful clinical assessment precludes the necessity of biopsy and emphasize the importance of conservative management of this transient problem.