Sixteen cases of congenital cystic hygroma were identified through a r
etrospective review of surgical pathology and autopsy records. Tissue
sections of the cystic hygromas were available in 10 cases and were ex
amined histopathologically and for reactivity to factor VIII antiserum
. Of 13 cases with ultrasound examinations, cystic hygroma was diagnos
ed prenatally in 9. In 11 cases with successful karyotyping, six were
45, X. Histopathologic observations of lymphatic vascular architecture
were apparent in 10 cases, and immunoreactivity of the endothelium to
factor VIII antiserum was preserved regardless of the degree of autol
ysis.