a 33-year - old female multigravida presented to our institution for her prenatal care . at 25  weeks of gestation , a fetal sonogram reported a 1.3  cm    1.2  cm    1.0  cm cyst within the fetal liver ( figure 1 ) . at that time , it was uncertain whether it represented a choledochal etiology or an isolated parenchymal cyst . at 37  +  5  weeks of gestation , the mother was noticed to have oligohydramnios , which persisted despite the administration of intravenous fluids . she was admitted for induction of labor and a female newborn was delivered via vaginal delivery after 38  weeks of gestation . the physical examination of the infant soon after delivery showed a newborn girl with a birth weight of 3285  g , head circumference of 33.5  cm , chest circumference of 34  cm , abdominal circumference of 31.5  cm , and length of 51  cm . abdominal examination revealed a soft , nondistended abdomen , with no masses palpated . , we performed an abdominal sonogram that revealed a liver cyst in the right lobe of the liver , measuring 3.1  cm    1.8  cm    2.8  cm ( figure 2 ) . the gallbladder appeared unremarkable , with no intrahepatic biliary duct dilatation ( figure 3 ) . the hepatic function panel showed an aspartate aminotransferase level greater than 3 times the upper limit of normal ( 134  u / l ) . the infant remained asymptomatic and was discharged home with a total bilirubin level of 4.6  mg / dl , corresponding to the low - risk zone at 35  hours of life according to the bhutani nomogram . the baby was evaluated by our pediatric gastroenterologist who recommended repeating the sonogram to ensure stability . as such , a follow - up sonogram was performed at 4  months of life showing a cyst measuring 1.9  cm    1.1  cm    2  cm in the right lobe of the liver with no increased vascularity . she was reevaluated by pediatric gastroenterologist at 7  months of age when a new ultrasound was performed showing complete disappearance of the simple hepatic cyst ( figure 4 ) , with normalization of the hepatic function panel . the incidence of congenital hepatic cyst in the postnatal life is 2.5% . this incidence is lower during the prenatal period with a few cases described in the literature . they are more common in girls , not associated with cysts in other organs , and rarely communicate with the biliary tree . these cysts do not contain bile and arise from congenital or secondary obstruction of the biliary glands , which normally arise from the ductal plate at the hepatic hilum around the seventh week of gestation and continue to proliferate until adolescence . they are superficially located just under the liver capsule and are coated by a single layer of cuboidal or columnar epithelium , characteristic of the bile ducts . the research has shown that the epithelium lining the cyst is sensitive to hormones , especially estrogen , and also that the cysts tend to enlarge in patients on hormone therapy . hepatic cysts related to these disorders may also have a genetic component , and they can appear later in life . incidental finding of an asymptomatic lesion on antenatal imaging is the most common presentation of a congenital hepatic cyst . in infants , symptoms consist of abdominal distension , feeding difficulties , respiratory distress , and duodenal obstruction . cholestasis may also be observed in some cases due to the compression of the hepatic parenchyma and the biliary system by a large cyst . for older patients , symptoms may include abdominal pain , nausea , and vomiting and rarely obstructive jaundice or portal hypertension . ultrasonography shows the congenital hepatic cyst as an anechoic unilocular fluid - filled space with a posterior acoustic enhancement . septations represent bridging of bile ducts and vessels and are commonly absent . magnetic resonance imaging ( mri ) typically reveals a well - demarcated water - attenuated lesion without enhancement after gadolinium with low - intensity signal on t1 and high - intensity signal on t2 images . in our case , no mri was indicated as the infant was asymptomatic and appropriate follow - up was ascertained . the main differential diagnosis of congenital hepatic cyst includes solitary liver cyst and choledochal cyst . the former may contain bilious or nonbilious fluid and can have connection to the biliary tract . malignant transformation of a congenital hepatic cyst is extremely rare , and the only recognized risk factor for this transformation is a cyst size greater than 12  cm . management of congenital hepatic cyst is conservative with periodic ultrasound monitoring to ensure their stability , especially for large cysts ( 4  cm in diameter ) . most simple hepatic cysts are benign in nature and have a spontaneous resolution as in our patient . surgical intervention with aspiration , sclerotherapy , or excision is indicated only for severe cases , such as hydrops , progressive enlargement , hemorrhage , torsion , or if image characteristics prompt diagnostic doubt . compression of intrahepatic structures due to an increase in the cyst size also prompts surgery ; hence , ultrasound follow - up is important . in 2 previous series published , only 2 of 12 infants with simple hepatic cysts required surgical intervention due to gradual enlargement and symptoms , and the others needed no further intervention . it is crucial for the neonatologist to be familiar with the range of pathologies possibly causing this condition . accurate diagnosis is important followed by periodic surveillance with ultrasonography for optimal management of large asymptomatic lesions , as many cysts can produce obstructive biliary complications and have malignant potential . surgical treatment with partial or total removal of the cyst is the favored treatment in neonates with a large symptomatic lesion , with an objective of excising as much of the cyst wall as possible without causing damage to the surrounding vital organs .
congenital hepatic cyst is a rare and nonsymptomatic condition in infants and children . 
 its incidence is 2.5% in the postnatal life with a much lower incidence in the prenatal period . 
 incidental finding on antenatal imaging is the most common presentation . 
 we present a case of a newborn in whom fetal ultrasound detected a cyst within the fetal liver . 
 postnatal imaging revealed a liver cyst in the right lobe of the liver , with no other intrahepatic structure affected . 
 liver function tests were abnormal , but the patient was asymptomatic . 
 posterior follow - up imaging showed a minor decrease in size . 
 management of congenital hepatic cyst is usually conservative , done with periodic ultrasound monitoring . however , surgical treatment is the mainstay of treatment when hydrops , progressive enlargement , hemorrhage , torsion , or compression of adjacent structures occurs . 
 malignant transformation can occur , but it is extremely rare . partial or total removal of the cyst is the preferred treatment in neonates with a large lesion .