Case Report: Congenital simple hepatic cyst with late-onset fetal growth restriction and an unexpected neonatal phenotype

BackgroundCongenital simple hepatic cysts are rare fetal abdominal lesions whose prenatal diagnosis requires differentiation from other intra-abdominal cystic abnormalities. Their coexistence with fetal growth restriction (FGR) may complicate diagnostic interpretation, particularly when additional congenital findings emerge after birth.Case presentationA 31-year-old woman was referred at 31 + 2 weeks for third-trimester ultrasonography. A well-defined avascular cystic lesion of probable hepatic origin was identified together with severe fetal smallness and persistent oligohydramnios. Serial ultrasonography demonstrated modest cyst enlargement without biliary dilatation, mass effect, or hydrops. Severe late-onset FGR was diagnosed on the basis of an estimated fetal weight below the 3rd percentile and classified as stage I according to the Barcelona staging system in the absence of advanced Doppler abnormalities. Delivery occurred at 37 + 2 weeks. Postnatal ultrasonography confirmed a simple hepatic cyst. Microcephaly and left-hand syndactyly with digital hypoplasia were additionally identified. The infant remained asymptomatic and was managed conservatively. At 2 months, neurological examination and transfontanellar ultrasonography were normal.ConclusionA congenital simple hepatic cyst and late-onset FGR may coexist without an established causal relationship. In this case, the unexpected postnatal identification of microcephaly and a limb anomaly broadened the differential diagnosis underlying severe fetal smallness and underscored the importance of avoiding diagnostic anchoring. Longitudinal prenatal-to-postnatal assessment enabled appropriate FGR management and conservative follow-up of an uncomplicated hepatic cyst, while the broader neonatal phenotype warrants continued developmental surveillance, genetic counseling, and diagnostic genetic testing.