Congenital malformations - Edocr

CHAPTER 51 CYSTIC HYGROMA 361
and outcome; (1) early gestation, normal karyotype—good
prognosis, (2) early gestation,
abnormal karyotype—poor prognosis, (3) late
gestation/postnatal-variable prognosis depending
on the size.
GENETIC COUNSELING
Genetic counseling and recurrence risk depend
on the timing of appearance of cystic hygroma,
associated chromosomal abnormality, identification
of any associated syndromes, and family
history. If a chromosomal abnormality or syndrome
is identified, recurrence risk would be
based upon the pattern of inheritance of that
particular disorder.
After an early gestation diagnosis of cystic
hygroma, the overall risk of fetal aneuploidy is
50% and a residual risk of major structural malformation
or spontaneous death in cases with
normal karyotype is also approximately 1 in 2.
However, a nearly 90% chance of normal pediatric
outcome can be anticipated in cases
with normal karyotype with no other structural
malformations on evaluation. The survival
rate at 1 year for the live-born infants
with cystic hygroma is close to 90%. The recurrence
risk in cases with an abnormal karyotype
unrelated to a parental chromosomal
rearrangement is low and is in the range of 1%.
However, the risk in the presence of a suspected
syndrome or in cases of isolated cystic
hygroma with a positive family history of cystic
hygroma could be as high as 25%. The recurrence
risk for a case with isolated cystic hygroma
and normal karyotype with negative
family history is unknown but likely to be no
different than in the general population. Prenatal
ultrasound screening should be offered
in all subsequent pregnancies.
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