[Sternocleidomastoid tumor].

A case of pseudotumour of the sternocleidomastoid muscle in a three-week old child is reported. The tumour resolved spontaneously within four months. Seventeen months later there was no sign of torticollis. This tumour is the most common cause of torticollis in newborn children. In 80-90% of the cases the tumour disappears within six months, the rest develop either a progressive or delayed torticollis, known as congenital muscular torticollis (CMT). Thus, CMT is a related condition, usually appearing at three to four years of age, and it may require surgical correction.