Perinatal prognosis in euploid fetus with cystic hygroma. Report of two clinical cases

Introduction: Cystic hygroma (CH) is a rare congenital anomaly of the lymphatic system. It is characterized by cystic lesions predominantly in the fetal neck and its prenatal diagnosis has been associated with increased perinatal mortality, aneuploidy, and congenital malformations. Case presentation: Two cases of cervical cystic hygroma diagnosed during the second trimester of gestation are presented, one of them associated with bilateral clubfoot. Both fetuses underwent karyotyping by amniocentesis, which established that both were euploid (46 XY and 46 XX), as well as fetal nuclear magnetic resonance imaging that showed no associated major malformations. In the interdisciplinary follow-up performed 1 year after birth, no findings consistent with genetic syndromes or neurodevelopmental alterations were observed in either of the 2 cases. Conclusions: CH is a marker of poor fetal prognosis; however, euploid fetuses with this condition have a better prognosis if their lesion resolves, do not progress to hydrops fetalis, and do not present other associated malformations. Euploid fetuses with CH require specific genetic studies for RASopathies, such as Noonan syndrome, which were not available in the clinical approach of the 2 cases presented; however, typical postnatal characteristics of the disease were not evident in the clinical genetic evaluation.