What Do the Ultrasound Findings Reveal About an Infant With Torticollis?

Case and images courtesy of Thaddeus W. Herliczek, MD, MS, 
Warren Alpert School of Medicine, Brown University, Providence, RI.

THE CASE: A 4-week-old girl is brought for evaluation of progressive torticollis. The mother is also concerned about a lump in the baby’s neck. The infant was delivered vaginally with vacuum assistance at 39 weeks’ gestation after an uncomplicated pregnancy.

Examination reveals a well-appearing neonate whose face and head deviate persistently toward the right. A firm, painless mass of about 15 3 10 3 10 mm is noted at the left anterolateral aspect of the infant’s neck. There are no superficial cutaneous abnormalities. Remaining physical findings and vital signs are normal.

Ultrasound images of the neck are shown.

Which of the following best describe the ultrasound findings?

A. Rhabdomyosarcoma.

B. Infantile myofibroma.

C. Left fibromatosis colli.

D. Normal right sternocleidomastoid muscle.

(Answer on next page)

The correct answers are C, left fibromatosis colli, and D, Normal right sternocleidomastoid muscle.

Discussion: The ultrasound images show the characteristic sonographic features of fibromatosis colli, involving the left sternocleidomastoid (SCM) muscle (A and B). The normal right SCM muscle (C and D) is shown for comparison.

Fibromatosis colli (also known as congenital muscular torticollis) is idiopathic fusiform enlargement of the SCM muscle that typically occurs between 2 weeks and 2 months of age. It is an acquired condition, probably related to SCM muscle injury in utero or during delivery. Trauma to the muscle results in fibrous infiltration of an intramuscular hematoma. Fibrous infiltration results in muscle shortening and head tilt toward the unaffected side. A palpable mass may or may not be present.

Ultrasonography is the first-line imaging modality in the infant with a painless neck mass and torticollis.

Fibromatosis colli usually resolves spontaneously; however, recovery may be assisted by physical therapy and stretching of the affected SCM muscle. This patient’s torticollis resolved without complication after physical therapy.