Perinatal autopsy findings in three cases of jugular lymphatic obstruction sequence and cardiac polyvalvular dysplasia.

Three infants with a prenatal diagnosis of Noonan's syndrome suffered fetal hydrops and immediate neonatal death. The infants all had the external appearance of jugular lymphatic obstruction sequence with wide-spaced nipples, redundant posterior nuchal skin, and edema of the dorsa of the feet and hands. All 3 demonstrated thick, redundant leaflets of all 4 cardiac valves, and 2 had a membranous ventricular septal defect. One female infant had a mutation of the PTPN11 gene. Two males had no common mutation of PTPN11. The males demonstrated other abnormalities in common, including small penis, testicular malformation, rosette-like appearance of the pituicytes, and an eosinophil infiltration of the pancreatic islets with islet cell hypertrophy. Detailed anatomy of cases of lymphatic obstruction sequence fetuses can be correlated with an increasing number of genetic mutations associated with Noonan's syndrome and related syndromes in mice and humans.