Infant with torticollis since birth and a right neck mass

US of fibromatosis coli
Transverse US of the neck shows a normal sized hyopechoic left sternocleidomastoid muscle lying above the jugular vein and carotid artery. The right sternocleidomastoid muscle is more heterogenous in echotexture and is 3-4 times larger in size than the left.

The diagnosis was fibromatosis colli.