This is a second trimester fetus for which several images were provided.

Findings:

There is an echogenic mass located inside the brain. On the transverse sections, this  round echogenic mass is localized in the midportion of the brain with distortion of the thalami and the cavum septum pellucidi. On sagittal scans the tumor is to the basis of the skull and beneath the corpus callosum. It seems to be in close relationship with the sella tursica. On the sagittal plane on the video clip, the basis of the tumor originates from the sella turcica.

Differential diagnoses

Congenital intracranial tumors are very rare and only account for 0.5-1.5% of all childhood brain tumors. Those with prenatal manifestation are even rarer. By far the most frequently reported are the intracranial teratoma and primitive neuroectodermal tumor. Other tumors and masses that have been reported include

• glioblastoma multiform
• medulloblastoma
• optic chiams and hypothalamic glioma
• metastasis of choriocarcinoma
• astrocytoma
• fetus-in-fetu
• lipoma of the corpus callosum

Many of you have suggested choroid plexus papilloma, but aside from being in the ventricles which is not the case in this case, they are very rare, and there are no report of a case having been diagnosed or recognized prenatally. If you have had such a case please let us know.

Sonographic differentiation can be guided by the composition of the tumor (solid, cystic, mixed), the association with hydrocephaly, the presence of calcifications, and the localization (unilateral, median) (Sherer et al).

Additional information can be obtained by MR imaging of fetal intracranial structures. Eventually, neonatal brain biopsy will be necessary to assign a definitive diagnosis since images of two different tumors can appear the same (Chung et al).

However because of the midline position and its close  relationship with the sella tursica, this round echogenic mass is most likely a craniopharyngioma. This was later on confirmed by pathological examination.

Discussion

The incidence of congenital craniopharyngioma is extremely rare. Data from Takaku (1978) et all and Wakai et all (1984)¹ showed that the frequency of congenital craniopharyngioma was about 3.5-4.0% of all congenital brain tumors. A more recent review of all midline supratentorial neoplasms in children and young patients by Fernandes et al (1990)² revealed a frequency of 3.5%.

The prenatal diagnosis of this condition has been made previously on only 4 occasions^3,7-9. All cases demonstrated a centrally located echogenic mass without dilatation of the ventricular system. All three cases have been detected after 26 weeks, although reviewing the tapes in one case showed already the presence of a tumor at 19 weeks. No associated malformations were present.

This usually rapidly growing tumor has a poor prognosis. Complete surgical excision is difficult, and additional radiation therapy may be needed.

However, there is a high probability of severe morbidity (blindness and endocrine deficit)³.

See Also craniopharyngioma

References

1. Developmental pathology of the Embryo and the Fetus; Eds Dimmick and Kalousek, 1992, Lippincott Company
2. Fernandes VS, Bisi H, Camargo RY, et al: Retrospective analysis of the incidence of midline supratentorial neoplasms in children and young patients: craniopharyngioma, hypophyseal and pineal neoplasma. Rev Paul Med 108: 71-7, 1990
3. Lacrampe M, Jeanty P: Craniopharyngioma. The Fetus, Volume 1:3,11-14 1991
4. Sherer DM, Onyeije CI: Prenatal ultrasonographic diagnosis of fetal intracranial tumors: a review. Am J Perinat 15, 319, 1998.
5. Magee JF, McFadden DE, Pantzar JT: Congenital tumors. In: Developmental pathology of  the embryo and fetus. Eds Dimmick JE and Kalousek DK, 1992, pag 235, Lippincott Company
6. Chung SN, Rosemond RL, Graham D: Prenatal diagnosis of a intracranial tumor. J Ultrasound Med17: 521-3; 1998.
7. Janisch W, Flegel HG Craniopharyngioma in a fetus Zentralbl Allg Pathol 1989;135(1):65-9
8. Snyder JR, Lustig-Gillman I, Milio L, Morris M, Pardes JG, Young BK Antenatal ultrasound diagnosis of an intracranial neoplasm (craniopharyngioma) .JCU J Clin Ultrasound 1986 May;14(4):304-6
9. Freeman TB, Abati AD, Topsis J, Snyder JR, Beneck D, Lehman LB Neonatal craniopharyngioma Y State J Med 1988 Feb;88(2):81-3