The authors report a preterm neonate with dysmorphic traits and cleft palate who was born preterm because of precipitous delivery and died soon after birth notwithstanding neonatal intensive care unit (NICU) support. The cytogenetic analysis on fibroblasts from post-mortem skin biopsy demonstrated a Pallister-Killian syndrome (PKS). PKS is a cytogenetically syndrome characterized by a tissue limited mosaic distribution of one isochromosome 12p (tetrasomy 12p). Clinical manifestations of PKS are variable, and some symptoms may overlap with other malformative syndromes, thus the correct diagnosis mainly depends on the demonstration of the specific cytogenetic abnormality.