Prenatal diagnosis of intracranial immature teratoma in the third trimester using 2D and 3D sonography.

Intracranial tumors are uncommon and represent 0.5-1.5 % of all pediatric tumors. Teratoma is the most frequent intracranial tumor found at birth. Large teratomas are extremely rare and have a guarded prognosis since they grow fast and cause brain tissue destruction. A 31-week primigravida was referred to our hospital for investigation of an intracranial mass seen in the fetus. Two-dimensional ultrasound showed a large heterogeneous solid mass with calcifications inside, measuring 5.3 × 4.8 cm. It was in the right cerebral hemisphere at the level of the middle and posterior fossa, thereby shifting the midline and causing severe ventriculomegaly that measured 3.5 cm at the level of the lateral ventricle. Three-dimensional ultrasound (3DUS) in multiplanar mode allowed us to assess the anatomical relationships between the mass and the midline structures. The neurosurgical team, who had suspected that the case was inoperable, was thus able to gain a better understanding of the case. Transfontanellar ultrasound was performed on the day after the birth and confirmed the previous findings. Moreover, a biopsy confirmed the histology of the mass: it was an immature teratoma. The infant died on the 24th day of life after a large expansion of head circumference. Intracranial teratomas are extremely severe because of their quick growth and mass effect, often leading to neonatal death within days. 3DUS is a new prenatal diagnostic method that makes it possible to assess the anatomical relationships between the mass and the intracranial structures, thus enabling better preoperative planning.