Nuchal translucency and lymphatic system maldevelopment.

We describe the histological examination of 18 aborted fetuses that had increased nuchal translucency (NT) between 11(+0) and 13(+6) weeks' gestation. The aim of this study was to assess the corresponding NT anatomic features by immunohistochemical (IHC) investigation. A morphological study was performed using lymphatic and blood endothelial specific markers, as well as smooth muscle actin (SMA). We found that all 18 cases were D2-40 positive, CD31 positive, and CD34 negative, suggesting the presence of nuchal lymph vessel ectasia. We found that 12/18 cases were SMA staining positive and 6/18 cases were SMA negative, suggesting that 6/18 cases had nuchal cystic lymphangiectasia, whereas 12/18 had cystic hygromas. The present data seem to confirm the reasonable hypothesis that lymphangiogenesis plays a relevant role in nuchal edema, increased NT, and that increased NT is the result of a lymphatic malformation or a delayed development of the lymphatic system.