Second trimester prenatal diagnosis of epignathus teratoma in ring X chromosome mosaicism with inactive ring X chromosome.

We report the second trimester prenatal echographic diagnosis of an epignathus teratoma in a female fetus with ring X chromosome mosaicism. The ring X chromosome mosaicism was present in the amniotic cell culture and in the teratoma and the ring X was inactive (X-inactive specific transcript (XIST) locus expressed). Hypoplastic left heart with valvular aortic stenosis and non-immune hydrops were additional findings, and are well-documented in Turner syndrome. The occurrence of epignathus teratoma in Turner syndrome has not been documented sofar.