Ultrasound observations of a malignant cervical teratoma of the fetus in a case of polyhydramnios: case history and review.

A case report is given concerning an extremely rare case of malignant teratoma of the neck with mature and immature metastatic lesions in the lungs in an immature fetus. The ultrasound observations are reported. The differential diagnosis of masses in the fetal neck, as can be observed by ultrasound, is discussed, with a review of the literature on this subject.