Prospective ultrasound diagnosis of Pallister-Killian syndrome in the second trimester of pregnancy: the importance of the fetal facial profile.

The Pallister-Killian syndrome (PKS) represents a rare polymalformative complex characterized by a tissue-specific mosaic distribution of an additional isochromosome 12p and characterized by diaphragmatic hernia, rhizomelic limb shortening, facial anomalies and, rarely, acral hypoplasia. Since diaphragmatic hernia and acral hypoplasia can be also found in Fryns syndrome, the differential diagnosis between the two conditions depends on the demonstration of the 12p isochromosome by FISH. Prenatal diagnosis of PKS has been reported in cases submitted to karyotyping due to advanced maternal age or congenital anomalies detected on second trimester ultrasound. Among the ultrasound-detected malformations, little attention has been paid to facial anomalies. We describe a case in which PKS was prospectively suspected on the basis of the various anomalies detected at ultrasound, namely diaphragmatic hernia, rhizomelic limb shortening, and abnormal facial profile. The diagnosis was then confirmed by FISH on amniocytes and peripheral lymphocytes. In the present case, the disclosure of typical facial abnormalities significantly contributed to the differentiation between PKS and Fryns syndrome.