Congenital Hepatic Cyst

Congenital hepatic cysts (CHCs) are rare hepatobiliary malformations which typically present as a single, unilocular upper abdominal cysts in the fetal liver. They are usually discovered in the third trimester of pregnancy, but can also be identified in early gestation. CHCs are often asymptomatic at birth but may enlarge during pregnancy or after birth.

Q44.6 Cystic disease of the liver

K76.8 Other specified diseases of the liver: simple cyst of the liver

CHCs are a rare, but well-recognized condition in the fetus and neonate, however, prenatal detection is unusual. In a 22-year single institution series of antenatally diagnosed intra-abdominal cysts, no cases of hepatic cysts were identified(1),  and fewer than 30 cases prenatally detected have been reported in the literature (2). It is possible that these cysts are either not recognized or underreported as they are typically small and often  resolve or they become evident only in the third trimester and remain asymptomatic in the neonatal period (2, 3). With continued improvement in ultrasound resolution and increased uptake of routine third trimester scanning for estimation of fetal weight in the third trimester, we expect that CHC may be detected more frequently than in the past.

Simple CHCs are thought to arise from aberrant bile ducts or intrahepatic peribiliary glands which are not connected to the biliary tree. (2) Other causes of liver cysts include mesenchymal hamartomas, which are often large and multicystic and may grow during pregnancy. Mesenchymal hamartomas may be seen in conjunction with mesenchymal villous hyperplasia or dysplasia and are thought to occur as a result of inadequate blood supply to the placenta which causes can contribute to ischemia in portions of the liverresulting in large multicystic masses in the second and third trimesters. The rarest of the hepatic cysts are congenital hepatic foregut cysts. These are thought to be a result of an abnormal foregut bud in the thorax which is trapped in the liver through a patent pleuroperitoneal canal (4).

Simple hepatic cysts are usually lined by a single layer of cuboidal or columnar epithelium and surrounded by a fibrous capsule. (2) Mesenchymal hamartomas are overgrowths of liver cells and stroma. The cystic portions of the specimen represent tortuous bile ducts lined by loose connective tissue. (2) Epidermoid cysts of the liver are characterized by nonkeratinizing squamous to transitional-type epithelia (5).

Typically, hepatic cysts are isolated findings. However, when any structural abnormality is identified, a thorough evaluation of the remainder of the fetal anatomy is suggested to rule out other anomalies. Mesenchymal hamartomas may be seen in conjunction with multicystic placental masses (6).

None known.

CHCs are typically anechoic unilocular masses located in the fetal liver, which are typically discovered incidentally when the abdominal circumference measurement is obtained.

Small cysts in the liver, measuring 3-5 mm, have been identified in the first trimester at 12-13 weeks’ gestation (7, 8). When identified early in pregnancy, these small cysts may disappear with advancing gestational age. (8) Most liver cysts, however, are first identified in the third trimester.

CHCs identified range in size from small, <1 cm, (Cases 2,3) to quite large (Case 1). Occasionally, these cysts are so large that they fill the abdominal cavity (9). Most are unilocular; however, multiloculated liver cysts have been occasionally been observed (Case 3, 10). When small, CHCs do not alter the course of the umbilical vein; however, when they become large, the umbilical vein may be displaced by the cyst (11).

Any abdominal cystic mass should be observed to ensure that it does not have peristalsis. Colour Doppler should be used to identify the umbilical vein and to ensure that the mass is not vascular. The mass should be separate from the fetal gallbladder, and care should be taken to exclude a choledochal cyst (see VISUOG chapter on Choledochal cyst). The remainder of the structures in the upper abdomen should be evaluated to ensure that the cyst is clearly separate from the stomach, duodenum, kidney, adrenal gland and spleen.

Mesenchymal hamartomas are suggested when a large (5-14 cm), multiloculated cyst is identified in conjunction with multicystic mass in the placenta. Maternal α-fetoprotein and ẞ-human chorionic gonadotropin (hCG) levels may be elevated in these cases. These lesions can grow rapidly and fetal hydrops and polyhydramnios may occur (2).

The main differential diagnoses include any cystic mass which can arise in the upper abdomen. A careful evaluation of the liver and surrounding organs is indicated as cysts in the upper abdomen may arise from a variety of tissues. Colour Doppler can be helpful to characterize the mass as avascular and to exclude an umbilical vein varix. Connections between the cyst and the gallbladder, which would suggest a choledochal cyst, should be excluded as early neonatal evaluation and surgical excision of choledochal cysts is mandatory to prevent long-term complications. The resolution of modern ultrasound equipment is likely sufficient to determine the size, location and appearance of the cystic mass.

Small cystic areas in the liver may be confused with other common cystic masses in the upper abdomen including:

• Adrenal cyst
• Cystic pulmonary sequestration
• Duodenal atresia
• Enteric duplication cyst
• Hydronephrosis
• Pancreatic cyst
• Renal Cyst
• Splenic cyst
• Umbilical vein varix

If the mass is large, additional considerations include:

• Bladder distention
• Omental cyst
• Ovarian cysts
• Urachal cyst       

If the mass is multilocular, additional considerations include:

• Cystic meconium peritonitis
•  Mesenteric cysts

The identification of a CHC should prompt a detailed examination of the fetal abdomen and adjacent organs to rule out other causes for abdominal masses. Prenatal compromise has been reported in fetuses with huge CHCs (10) and in cases with coexisting placental mesenchymal dysplasia (6), therefore prenatal diagnosis of a CHC requires serial ultrasound examinations to monitor the size of the cyst and to exclude polyhydramnios and fetal hydrops. Fetal MRI is not typically necessary for the management of these cases.

Hepatic cysts are typically isolated findings. Amniocentesis for karyotype, microarray and additional studies is not indicated unless there are additional ultrasound findings which raise concern for aneuploidy. Isolated liver cysts are not typically associated with congenital fetal infections.

Routine screening for CHC is not indicated.

CHCs are often relatively small during pregnancy and remain small and asymptomatic during infancy (2, 3).  These cysts may be incidental findings and not require surgical treatment. Prenatally reported CHCs are typically somewhat larger and may or may not require surgical treatment. Long-term prognosis is excellent even for those cases which require surgical removal.

Once a hepatic cyst is identified, additional ultrasound examinations should be considered to monitor the size of the cyst in the prenatal period. Typically, these cysts demonstrate only minimal enlargement during the pregnancy (11). Occasionally, aspiration of the cyst in utero has been performed prenatally and postnatally with complete resolution of the cyst (12), or with the aim to decrease respiratory complications in the neonate (9).

Some huge, multiloculated hepatic cysts have caused fetal distress, necessitating delivery by Cesarean section. (10) In general, Cesarean delivery is not indicated as fetuses with large lesions may deliver vaginally. (13)

In the neonatal period, hepatic cysts are typically monitored with abdominal ultrasound to assess size and internal characteristics. Some small cysts discovered in the third trimester have been observed to disappear by 6 months of age. (8) Surgical removal is not necessary if the neonate remains asymptomatic and if the cyst remains small. Large cysts, however, may obstruct the biliary tree or the inferior vena cava (2) and the urinary tract. (3) Symptoms include respiratory problems, jaundice, and pain and are typically related to the size rather than the location of the cyst as large cysts can cause compression of adjacent organs. (3)

If the neonate develops symptoms or if the cyst enlarges significantly, further imaging with MRI or CT can provide additional images of the cyst and surrounding structures and may be helpful for surgical planning (11).  Preoperative evaluation of tumour and germ cell markers including α-fetoprotein and ẞ-hCG can be considered if the tumour is thought to be potentially malignant. Many surgeons chose to excise these cysts with laparoscopic techniques which have minimal complications and rapid postoperative recovery in children (11, 14).  Some cases require marsupialization or subtotal excision (2).  There are rare cases of squamous cell metaplasia arising from these cysts, which is typically diagnosed after age 30. (2)

^{1. Thakkar HS, Bradshaw C, Impey L, Lakhoo K. Post-natal outcomes of antenatally diagnosed intra-abdominal cysts: a 22-year single-institution series. Pediatr Surg Int 2015;31:187-190.}

^{2. Allan M, Davenport M. Congenital hepatic cysts. In: Lima M, Reinberg O (eds) Neonatal Surgery. Contemporary Strategies from Fetal Life to the First Year of Age. Cham: Springer Nature, Switzerland AG, 2019: 401-408.}

^{3. Celebi S, Kutluk G, Bestas CB, Kuzdan O, Sander S. Current diagnosis and management of simple hepatic cysts detected prenatally and postnatally. Pediatr Surg Int 2014;30:599-604.}

^{4. Betalli P, Gobbi D, Talenti E, Alaggio R, Gamba P, Zanon GF. Ciliated hepatic foregut cyst: from antenatal diagnosis to surgery. Pediatr Radiol 2008;38:230-232.}

^{5. Morrow MK, Li A, Perez-Atayde AR, Vargas SO. Congenital epidermoid cyst of the liver: a rare entity characterized by antenatal onset, slow postnatal growth, and consistent histologic and immunohistologic features. Pediatr Dev Pathol. 2020;23:181-188.}

^{6. Ruhland B, Schroer A, Gembruch U, Noack F, Weichert J. Prenatal imaging and postnatal pathologic work-up in a case of fetal hepatic hamartoma and placental mesenchymal dysplasia. Ultrasound Obstet Gynecol 2011;38:360-362.}

^{7. Sepulveda W, Dickens K, Casabuenas A, Gutierrez J, Dezerega V. Fetal abdominal cysts in the first trimester: prenatal detection and clinical significance. Ultrasound Obstet Gynecol 2008;32:860-864.}

^{8. Bronstein M, Nizar K, Weiner Z. Significance of early prenatal diagnosis of fetal hepatic cyst. J Clin Ultrasound 2009;37:65-68.}

^{9. Okumura M, Liao AW, Brizot ML, Zugaib M, da Silva MM. Sonographic detection of a giant solitary hepatic cyst in utero. J Ultrasound Med 2008;27:1663-1665.}

^{10. Mittermayer C, Bettelheim D, Horcher E, Fakhari M, Deutinger J, Bernaschek G. Prenatal sonographic detection of a giant multiseptate hepatic cyst in the third trimester. Ultrasound Obstet Gynecol 2002;20:97-98.}

^{11. Sepulveda W, Sepulveda F, Gonzalez G, Arce C, Alcalde E. Congenital hepatic cyst: prenatal and postnatal imaging findings. Ultrasound (in press), DOI: 10.1177/1742271X20970601.}

^{12. Ito M, Yoshimura K, Toyoda N, Tanaka H. Aspiration of giant hepatic cyst in the fetus in utero. Fetal Diagn Ther 1997;12:221-225.}

^{13. Berg C, Baschat AA, Geipel A, Krapp M, Germer U, Smrcek JM, Sigge W, Gembruch U. First-trimester diagnosis of fetal hepatic cyst. Ultrasound Obstet Gynecol 2002;19:287-289.}

^{14. Linden AF, Pulcrano ME, Duffy BJ, Lange PA, Tsung DY, Hartman GE, Kane T, Chahine AA. Laparoscopic excision of congenital hepatic cysts in the pediatric population: a case series and literature review. J Laparoendosc Adv Surg Tech A 2016;26:493-497.}

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