Ultrasound is the modality of the first choice. Findings on ultrasound examination show focal or diffuse enlargement of sternocleidomastoid muscle giving rise to a fusiform, ellipsoid appearance and primarily involving the lower two third of the muscle belly. No cysts are visible in the lesion ³.

Though fibromatosis colli is said to be associated with forceps delivery, difficult labor implicating birth trauma or cesarian section, it is not a hematoma. It is classified as a benign tumor of infancy. It is also called the sternocleidomastoid tumor of infancy (SCM tumor of infancy) or pseudotumor of infancy ¹. Mostly, these tumors are unilateral and affect the right sternocleidomastoid muscle; rare cases of bilateral tumors are reported in the literature. Boys are more affected than girls ².

SCM tumor of infancy is rare, found in less than 1 per cent of newborn infants. However, it's the most common cause of congenital muscular torticollis.

Most newborn infants show improvements within four weeks with local massage, active and passive stretching ¹. So parents should be reassured about good prognosis