Sternocleidomastoid Tumor of Infancy

What is sternocleidomastoid tumor of infancy?

A sternocleidomastoid tumor of infancy, also known as fibromatosis colli of infancy, is a rare benign mass in the muscle on the side of the neck. The tumor is usually on the right side, and is firm, measuring a couple centimeters in diameter. It appears in a newborn, usually between the second and fourth weeks of life.

Many tumors go away within a year without any treatment. With stretching exercises, most will go away within six months. In a small percentage of cases the tumor persists beyond a year despite stretching. In these and other cases where there is early deformity of the face or body, surgery may be recommended.

Although an SCM tumor of infancy is rare, appearing in less than 1 percent of newborns, it’s the most common of the congenital muscular “torticollis” conditions, which means, “twisted neck.” SCM tumor of infancy affects boys more often than girls.


Experts don’t yet know what causes SCM tumor of infancy. Although the tumor often appears in babies who were breech or whose deliveries were long and difficult, studies have disproved a cause-and-effect relationship. Some experts have speculated that minor soft tissue abnormalities developing within the neck muscle early in gestation or crowding within the uterus might have led to an SCM tumor of infancy.

Signs and symptoms

Children with an SCM tumor of infancy share many of the same symptoms:

  • A firm lump that appears on the side of a newborn’s neck, usually between the second and eighth weeks of life; viewed up close, it appears to be part of the neck muscle
  • The lump is not attached to the skin and is able to be moved when manipulated
  • A neck that bends slightly
  • A head that tilts
  • Facial asymmetry
  • Flat spot on the side of the head
  • Baby preferring to look in the direction away from the affected neck muscle
  • Baby that was positioned breech late in pregnancy
  • Delivery that was long and difficult

Testing and diagnosis

Your primary care provider may suspect an SCM tumor of infancy by closely looking at it and examining how it feels and responds to touch. But your primary care provider will likely refer your child to a specialist known as an otolaryngologist (ear, nose and throat specialist), to confirm a diagnosis through further testing and determine the best treatment, if any is needed.

During the evaluation, the otolaryngologist:

  • Will perform a physical exam of your child’s head and neck and gather a medical history.
  • May rarely perform a rapid screening test, known as a fine-needle aspiration cytology (FNAC) to examine the cells. Your child will be sedated for this safe, minor surgical procedure. It involves inserting a hollow needle into the mass to remove cells for examination under a microscope. By examining the cells, an ENT can differentiate an SCM tumor of infancy from other conditions, including a branchial cyst, thyroglossal cyst, infantile fibromatosis, hemangioma, cystic hygroma, and cancerous lesions including neuroblastoma and lymphoma.
  • May perform an ultrasound to locate the tumor site, determine other physical characteristics of the tumor and the extent of it, and predict how well it will go away on its own.


Well over 90 percent of these tumors go away within six months by following a daily regimen of stretching exercises, and repositioning procedures that an ENT will recommend. Sometimes, an ENT arranges a visit with a physical therapist, to demonstrate  the exercises and to work with the parents until they are well-practiced with the exercises. The physical therapist will want to watch the parents perform the exercises and schedule follow-up visits to check technique and progress.

In a small percentage of SCM tumor of infancy cases, surgery is necessary.

There are a variety of factors that help guide an ENT’s treatment decision, including:

  • The age of your baby
  • The findings from the ultrasound, which can help to predict how well the SCMI will respond to stretching exercises
  • The severity of the SCM tumor of infancy
  • The ability of caregivers to consistently perform the exercises and repositioning procedures
  • A diagnosis of a flat spot on your baby’s head
  • Whether your baby has facial asymmetry or other bodily deformities
  • Whether your baby’s motor skills are affected by the SCM tumor of infancy

Treatment options include:

  • Passive stretching exercises. They involve gentle passive range of motion and strengthening exercises for your baby’s neck. Success of the exercises depends upon properly holding your baby by the shoulders and positioning your hands in the right spots, as well as the proper execution of them. Often two caregivers are needed to rotate your baby’s neck to the side of the affected muscle, while the other caregiver is holding your baby in place. Gentle, firm pressure is applied and the neck is rotated to its limit and held for several seconds. The procedure is generally repeated 10 times, twice daily.
  • Repositioning procedures. These involve active range of motion exercises. Also, the physical therapist will demonstrate ways to handle, feed, carry, play with and position your baby as well as ways to encourage proper posture.
  • Massage. A special method of massage can increase pain-free range of motion.
  • Customized corrective helmet or molding cup for a baby who has a flat spot on his head in addition to the SCM tumor of infancy.
  • Surgery. This is generally considered if SCM tumor of infancy persists after a year despite stretching exercises and other non-invasive treatment measures. Other considerations for surgery: your baby’s neck continues to have significant range of motion problems after six months of exercises or your child is older upon diagnosis of SCMI. The surgical techniques vary slightly depending on the SCM tumor of infancy and involve cutting, manipulating, lengthening and then stitching muscles in order to correct them. Surgery often requires a neck collar and physical exercises for several weeks or months afterwards.


In about half the cases, SCM tumor of infancy goes away naturally, within a year or so, without any treatment at all. In many other cases, however, untreated SCM tumor of infancy leads to deformities in the head, neck, back, and even hips. The severity of the SCM tumor of infancy is a major factor in whether deformities will result or have already appeared in a newborn.

Even significant cases of SCM tumor of infancy can go away by consistently following a regimen of stretching and repositioning exercises. Only a highly trained ENT can help to assess and predict how well any particular case of SCM tumor of infancy will respond to exercises.

More severe cases of SCM tumor of infancy are successfully corrected through surgery; an exercise regimen and a cervical collar are generally recommended for a period of time.

Occasionally, regardless of the severity of your baby’s SCM tumor of infancy, your child’s posture may temporarily return to a more “twisted” state; this can happens during periods of growth, illness, teething, and development of new motor skills.

Follow-up care

Depending on your child’s treatment plan, your ENT will schedule follow-up visits to check the improvement of your baby’s SCM tumor of infancy.

To initiate the exercise regimen, your ENT may demonstrate the exercises and watch you perform the exercises to confirm proper technique. At CHOP, the ENT team will also coordinate care with a PT to work with you on an extended basis to ensure proper technique and observe technique at two or more follow-up visits scheduled within the first several weeks.

Post-surgery follow-up visits will be scheduled according to the surgical technique performed. Physical therapy is also initiated, often one week after surgery and may last for six months. The therapy is done on a daily basis and may be taught to parents.

Why choose CHOP

At CHOP, our otolaryngology team is highly trained and experienced in treating all rare disorders of the neck (and head and throat). In addition, they have extensive experience in the latest surgical techniques used for every type of neck mass.

Reviewed by Jennifer M. Spellman, MSN, CRNP, CORLN