Sternocleidomastoid Tumor of Infancy

Also known as: fibromatosis colli of infancy, SMT, SCM.

What is sternocleidomastoid tumor of infancy?

The sternocleidomastoid is a neck muscle which joins the base of the skull to the collar bone. A sternocleidomastoid tumor of infancy is a rare, benign (non-malignant, non-cancerous or spreading) neck mass/lump (usually on the right side) that appears around the second and eighth week after birth, more often in boys, and often causing the baby’s head to be tilted to one side and be rotated to the other (torticollis -“twisted neck”).

What causes sternocleidomastoid tumor of infancy?

The exact cause of sternocleidomastoid tumor of infancy is not entirely clear. It appears to be related to a breech or a long and difficult delivery, or the fetus being cramped within the womb.

What are the symptoms of sternocleidomastoid tumor of infancy?

Along with the physical presence of the tumor, which seems to be part of the muscle,   the lump may also cause the neck to bend slightly, the head to tilt or cause an asymmetrical face or a flat spot on the head.

What are sternocleidomastoid tumor of infancy care options?

In most cases, a sternocleidomastoid tumor of infancy resolves on its own over six months with stretching, repositioning, and massaging exercises initially performed by a physical therapist and subsequently undertaken by the parents. Surgery is only necessary in rare cases if the tumor persists after conservative treatment failure.

Reviewed by: Jack Wolfsdorf, MD, FAAP

This page was last updated on: October 03, 2019 03:45 PM