A small painless nonmalignant swelling in the lower half of the sternomastoid muscle, appearing a few days after birth. It occurs when the neck of the fetus is in an abnormal position in the womb, which interferes with the blood supply to the affected muscle, and it is most common after breech births. The tumor may cause a slight tilt of the head toward the tumor and turning of the face to the other side. This can be corrected by physiotherapy aimed at increasing all movements of the body, but without stretching the neck.