A newly described thoracic vascular malformation in fetuses with Down syndrome.

Objectives: To report the association between thoracic vascular malformations observed in the first trimester of pregnancy and Down syndrome. Methods: The clinical features were reviewed of seven fetuses undergoing chorionic villus sampling (CVS) for increased nuchal translucency (NT) thickness, in which color Doppler ultrasonography revealed a vascular malformation in the fetal thorax. Results: The crown-rump length of the fetuses ranged from 58 to 78 mm and NT measurements ranged from 2.9 to 10.0 mm. Color Doppler allowed the identification of a highly vascular structure in the posterolateral portion of the fetal thorax, in proximity to the costovertebral angle, at the level of a four-chamber view of the heart. The lesions had a globular shape and were 4-6 mm in diameter, occupying almost one third of the hemithorax. Down syndrome was diagnosed in five out of the seven cases. In the only affected case that underwent postmortem examination, a hemangioma of the chest wall was demonstrated. In the two fetuses with normal karyotype, the lesion disappeared by mid-gestation. Conclusion: We report an association between the prenatal Doppler finding of a vascular tumor in the fetal chest and Down syndrome.