In
the last two decades, the
prenatal diagnosis of fetal
brain tumors by
ultrasound is a new aspect of fetal pathology. This makes a possible
understanding on antenatal natural history and pathophysiology of
most commonly detected fetal brain tumors. This ultrasound technique
opened a new possibilities in prenatal detection of tumors arising in
the unborn child. Fetal brain tumors are rare, and may result in
serious illness or even death in neonatal or fetal period. The
prenatal diagnosis of fetal tumors is significant in the well-being
of both the mother and the unborn child, as well with the perinatal
and neonatal result.
On ultrasound, fetal
brain
tumor usually appears as a large, solid and/or cystic tumor,
often replacing normal brain tissue and sometimes eroding the skull.
This supports the hypothesis that most brain teratomas, which was
based on the Greek word “monstrous tumor”, developed in the fetal
stage and developed upon growing. Although, teratomas is extremely
rare, this is the most frequently reported. A study from a group of
Korean radiologists shows that most fetal neoplasm can be detected by
a careful ultrasonographic examination. The main reported features
appeared in the ultrasound are the following: complete loss of
intracranial anatomy, the tumor may appear cystic, solid, or both,
there is rapid growth with intra-tumor changes, calcifications,
polyhydramnios (>50% of cases), hydrocephalus, pulmonary
hypoplasia, high cardiac output failure , and the teratoma is
normally located in 3rd ventricle subfrontal region, or in
subtemporal area of the brain. Their findings suggest that the
awareness of the presence of this tumor in the fetus may alter the
prenatal management of a pregnancy and the mode of delivery, and
facilitates immediate postnatal treatment. The detection of this
tumor is important, since most fetal brain tumor usually cause an
intrauterine or neonatal death. A cesarean section is required for a
delivery of an enlarged fetal head.
Another
type of fetal brain tumor is glioblastomas. Two to nine percent of
congenital brain tumor is accounted with glioblastomas. On an
ultrasound, the tumor is distinct from teratomas due to its
multi-cystic characteristics. Both congenital glioblastoma and other
congenital brain tumors may cause spontaneous intracranial hemorrhage
in a fetus and an infant. According to the group of Korean
radiologists, a total number of cases of hemorrhage in congenital
tumors is 18%, a rate much higher than that seen in the adults and
children. The rapid growth of congenital tumors may be related to
this higher incidence of bleeding, which explains the poor
forecasting on the development of glioblastomas. Also, in a few
reported cases, heart failure was one of the immediate cause of
death, which may have been due to anemia--the result from the
withdrawal of a large amount of blood by the highly vascular tumor.
There
are other types of fetal brain and face tumor such as
craniopharyngioma, lipoma of
the corpus callosum, oligodendroglioma, gangliocytoma, and choroid
plexus papilloma which are all slow moving tumors that may manifest
in early childhood until early stage of adolescence. With an prenatal
diagnosis through ultrasound, these tumors can be easily detected and
a course of medical actions can be implemented.
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