Aim: Pallister-Killian syndrome (PKS) is a rare chromosomal disorder, caused by tissue-limited mosaicism for an isochromosome 12p. Prenatal diagnosis of PKS is generally incidental. Although clinical presentation of PKS varies, cytogenetic findings are constant, and include a tetrasomy of chromosome 12p. We report a case of prenatally diagnosed PKS with unique dysmorphic feature: bifid cardiac apex, a type of morphology that has not been documented before. Case presentation: Our patient was the 38-year-old pregnant woman who underwent amniocentesis. Cytogenetic analysis of amniotic fluid detected a mosaic karyotype with a supernumerary chromosome (SMC) in 64 % of fetal amniocytes. To determine the chromosomal origin of SMC, fluorescence in situ hybridization was performed and tetrasomy 12p was confirmed: mos 47,XY,+mar[18]/46,XY[10].ishi(12p)(8M16/SP6++,CEP12+,VIJyRM2196-). Ultrasound examination showed a fetus with cleft lip, echogenic focus in the left ventricle of the heart and shortened fetal long bones. After receiving a genetic counseling for PKS, the woman requested a termination of pregnancy. A postmortem inspection of the fetus revealed a complex heart anomaly that includes bifid cardiac apex and ventricular septal defect. Conclusions: This report expands the clinical manifestations of PKS with a unique feature of bifid cardiac apex, and highlights the targeted prenatal diagnosis of PKS if specific ultrasound markers are present.; Cilj: Sindrom Pallister-Killian (PKS) rijedak je kromosomski poremećaj uzrokovan tkivno ograničenim mozaicizmom za prekobrojni izokromosom 12p. Prenatalno se dijagnoza PKS-a postavlja uglavnom slučajno. Iako je težina kliničke slike različita i varira od vrlo blage do izrazito teške, citogenetički nalaz uvijek uključuje tetrasomiju 12p. Ovim radom prikazan je prenatalno dijagnosticirani PKS s jedinstvenim dismorfološkim obilježjem: bifidnim srcem, koje do sada nije opisano u literaturi, kao dio kliničke slike ovoga sindroma. Prikaz slučaja: Tridesetosmogodišnja trudnica upućena je na amniocentezu. GTG metodom oprugavanja kromosoma utvrđen je aberirani mozaični muški kariotip s malim prekobrojnim marker kromosomom (engl. small supernumerary marker chromosome, sSMC) u 64 % fetalnih amniocita. Za određivanje podrijetla marker kromosoma korištena je metoda fluorescentne in situ hibridizacije te je utvrđena tetrasomija 12p: mos 47,XY,+mar[18]/46,XY[10].ishi(12p)(8M16/SP6++,CEP12+,VIJyRM2196-). Nalaz ultrazvuka ukazao je na fetus s rascjepom usne, ehogenim fokusom u lijevoj srčanoj klijetki te skraćenim dugim kostima. Po genetičkom savjetovanju, trudnica se odlučila za prekid trudnoće. Obdukcijom fetusa otkrivena je kompleksna srčana anomalija koja uključuje bifidno srce te ventrikularni septalni defekt. Zaključci: Ovaj prikaz slučaja prvi put opisuje jedinstveno dismorfološko obilježje bifidnog srca u PKS-u te naglašava važnost ciljanog pristupa u prenatalnoj dijagnostici PKS-a, ako postoje specifični ultrazvučni biljezi.