Spontaneous resolution of fetal mediastinal cystic hygroma.

We present a case of prenatally diagnosed mediastinal cystic hygroma with spontaneous resolution. To our knowledge, this is only the second case report of mediastinal cystic hygroma diagnosed prenatally, and the first one with spontaneous resolution perinatally. Our case shows that, in the absence of hydrops fetalis, mediastinal cystic hygroma in a fetus with normal karyotype can be associated with a normal outcome. Therefore we recommend fetal karyotyping, a careful search for other anomalies and close sonographic follow-up in such cases.