Diagnostic ultrasound ( PDFDrive )

CHAPTER 34 The Fetal Brain 1209
V
A
B
C
FIG. 34.37 Intracranial Teratoma. (A) Sonogram at 34 weeks
shows teratoma forming an echogenic mass with small cystic spaces
(arrows) displacing the midline to one side. The visible lateral ventricle
(V) is dilated. (B) In a different fetus, a facial teratoma invades the
brain. (C) Magnetic resonance image of same fetus in (B) shows
the intracranial extent of the tumor.
indings include polyhydramnios and intracranial hemorrhage.
Diagnosis is typically made in the third trimester on ultrasound
triggered by excessive uterine growth due to polyhydramnios,
although teratomas have been discovered as early as 17 weeks.
Fetuses suspected to have brain tumors should undergo detailed
ultrasound examination to look for associated abnormalities,
which can occur in about 12% of cases, especially involving the
face. Most have normal karyotype. MRI is helpful in characterizing
the mass, evaluating tumor extension, and diferentiating tumors
from other conditions such as hemorrhage, sinus thrombosis,
and vascular malformations. 251,252
Outcomes are poor, especially if tumors appear early. Overall
survival is about 28% and relates to size and location of tumor,
its histology, surgical resectability, response to chemotherapy,
and condition of the fetus at diagnosis. he large head size can
interfere with delivery and require cephalocentesis to allow vaginal
delivery. Of the few survivors, almost all have long-term neurologic
deicits. Slightly better survival is seen with choroid plexus
papilloma (73%) and meningeal tumors (36%). 251-253
Choroid plexus papillomas are large, inely nodular masses
that grow into the lateral ventricle and produce excessive CSF,
resulting in severe dilation of the entire ventricular system and
macrocephaly. Most are sporadic, but a few are associated with
Aicardi syndrome and giant pigmented nevi. Surgical resection
can be curative but is technically diicult because the vascular
nature of choroid plexus papillomas can result in fatal hemorrhage.
Overall survival is about 73%. 251
Intracranial lipomas are not “neoplasms” but rather a
malformation of meninx primitiva development. Instead of
resorbing at 8 to 10 weeks, the meninx persists and develops
into a mass of mature adipose tissue. he incidence is 4 to 40
per 100,000 autopsies. Most are near the corpus callosum, but
they can arise in any cistern. hey can interfere with callosal
development, and associated dysgenesis of the corpus callosum