Fetal mediastinal lymphangiomas

The purpose of this series was to evaluate the prenatal sonographic findings and postnatal outcomes in 2 fetuses with mediastinal lymphangiomas.

The fetal images were compared with postnatal imaging and surgical findings.

The 2 fetuses had anechoic mediastinal masses at 25 and 22 weeks, which proved to be lymphangiomas. One, located in the anterior mediastinum, also enveloped the superior vena cava, brachial plexus, phrenic nerve, larynx, and lower parts of the neck vessels and extended into the subcutaneous tissues of the anterior chest wall through an intercostal space. In the second patient, the lymphangioma appeared to be a unilocular cyst, which involved the deep tissues of the neck as well as the posterior and lateral mediastinum. Both required 2 interventions after birth.

Fetal mediastinal lymphangiomas appeared anechoic and sent extensions into the neck in the first case, around the superior vena cava, through the intercostal spaces to the skin, and around the brachial plexus in the second case, and deviated the trachea in both cases. In 1 case, there was also ectasia of the superior vena cava. This ability to entwine around vital structures can make it difficult to determine the extent of involvement on antenatal sonography and to remove lymphangiomas completely, and recurrence is common.