A male was born at 39 weeks of gestation, weighing 3670 g. Prenatal ultrasound scan showed severe polyhydramnios, requiring amniodrainage. A normal 46XY karyotype was obtained by amniocentesis. On examination, he had macrocephaly, with coarse facial features (broad anterior fontanelle, prominent forehead, bulbous nose, wide mouth), rhizomelic shortening of limbs, and ulnar deviation of the hands, with deep palmar and plantar creases (Figure, A and B). He developed respiratory distress syndrome, which required noninvasive mechanical ventilation. Cerebral, cardiac, and abdominal ultrasound findings were normal. On the electrocardiogram, a QRS axis −90°with wide QRS was observed, as reported in Noonan syndrome; however, genetic tests for Noonan syndrome were negative. A study of the HRAS gene was requested, confirming the diagnosis of Costello syndrome. Two months later, he was noted to have hypertrophic cardiomyopathy with pulmonary valvular stenosis.Costello syndrome, a rasopathy, is difficult to differentiate in the neonatal period from Noonan and cardiofaciocutaneous syndromes. 1 The majority of perinatal findings are sharedpolyhydramnios, prematurity, lymphatic dysplasia, macrosomia, macrocephaly, hypotonia, as well as cardiac and renal anomalies. Deep palmar and plantar creases are not specific to Costello syndrome but also are seen in C-like syndrome (usually with microcephaly), hemolytic anemia and lethal congenital nonspherocytic with genital and other abnormalities, Pierpont syndrome (usually without feeding difficulties), Smith-Kingsmore syndrome, wrinkly skin syndrome (with microcephaly and a generalized connective disorder), and Shashi-Pena syndrome. ■
