*Dept. of Radiology, Vanderbilt University, 21^st and Garland, Nashville TN 37232-5316. Ph: 615-343-0595, Fax: 615-343-4890

Synonyms: Non-parasitic, simple, solitary or unilocular hepatic cyst.

Definition: Fluid-filled space within the liver with a fibrous capsule and lined by cuboidal epithelium. Ninety percent are unilocular, and most are in the anterior segment of the right lobe. They range in size from a few millimeters to a few centimeters.

Prevalence: Second most common benign hepatic lesion, occurring in 2.5% of the general population, but only 6 cases have been described in fetuses. M1:F4.

Etiology: Unknown.

Pathogenesis: Unknown. Cuboidal epithelial lining and location within the portal triad suggest aberrant development of intrahepatic bile ducts with no connection to the normal billiary drainage.

Associated anomalies: Rarely, tuberous sclerosis may lead to cysts within the liver and kidneys. Peutz-Jeghers syndrome and omphalocele have also been reported in association with a simple cyst.

Differential diagnosis: Choledochal cysts, cystic dilatation of intrahepatic bile ducts, bowel duplication, and cystic structures within other abdominal structures.

Prognosis: Benign. These cysts grow slowly, and rare complications may be due to their enlargement, infection, or hemorrhage.

Recurrence risk: None known.

Management: Observation for ­asymptomatic cysts. Postnatally, symptomatic cysts may be sclerosed with ethanol under ultrasound guidance. Surgical excision may be indicated for refractory cysts.

MESH Liver, cyst BDE 0465 ICD9 751.62 CDC 751.610

Introduction

The prenatal diagnosis of hepatic cysts is uncommon. We present a case report and review of the literature.

Case report

A 23-year-old G₁P₀ patient was referred for evaluation of a female fetus suspected of hydronephrosis. The patient"s anamnesis was unremarkable. The ultrasound examination was normal except for the finding of an isolated cyst of the anterior segment of the right lobe of the liver. The patient was advised that the finding was probably more a curiosity than an anomaly, and she was rescanned by her referring obstetrician every month thereafter. The cyst grew proportionally to the fetus. The girl, now 4-year-old, is asymptomatic.

Figure 1: The cyst is symmetrical to the stomach.

Figure 2: The cyst is external to the gallbladder.

Discussion

Prevalence

Once thought to be rare, simple hepatic cysts are now routinely detected in adults with CT, MRI and ultrasound. The overall prevalence in the general population is about 2.5%, increasing with age¹. They may be found at any age and are more commonly seen in females. The right lobe of the liver is more often affected³. Only six cases of prenatally diagnosed simple hepatic cysts have been reported in the recent literature^5-7,28-29.

Pathogenesis and pathology

While the cause is not known, the classic pathologic description has advanced the hypothesis that such cysts are produced in aberrant bile ducts. This is thought to occur either by inflammatory ductal hyperplasia or by obstruction of the duct, retention of fluid, and subsequent cyst formation. This hypothesis is supported by the cuboidal histologic appearance of the cyst lining³. Recent immunohistochemical research reveals that simple cysts display mucin histochemical characteristics similar to cysts due to polycystic disease⁴.

Classification

Liver cysts are either congenital or acquired. A classification is provided in Table 1.

Table 1: Classification of hepatic cysts

Congenital

Acquired

Associated anomalies

There may be some evidence linking such cysts with tuberous sclerosis and Peutz-Jeghers syndrome, but this is uncertain^1,2.

Antenatal diagnosis

Definitive localization of a cystic structure within the fetal liver is usually possible. Differentiation from a vascular structure is simple with Doppler. As with other relatively benign abdominal cysts, the major importance of such a finding is differentiation from cystic lesions which may require urgent prenatal or neonatal treatment, or which may affect the viability of the fetus (Table 2).

Differential diagnosis

Aside from the six cysts mentioned above, another large cyst was erroneously interpreted as ascites within the abdomen⁸.  If the lesion can be localized to the liver, the differential diagnosis includes dermoid, lymphatic, and choledochal cysts; cystic dilatation of biliary ducts with Caroli"s disease (usually multiple), polycystic liver disease (usually multiple) and enteric duplication^3,6,9. Occasionally, it may be technically impossible to definitively localize a lesion to the liver. The differential diagnosis is then broadened to other intra-abdominal cystic structures, as shown in Table 2. In one series of 9 cases of prenatally diagnosed abdominal cysts, six were ovarian, one was a liver cyst, one was a Meckel"s diverticulum, and one represented a bowel duplication⁷.

Table 2: Differential diagnosis of hepatic cyst.

Management

There have been several reported cases of complications involving newborn infants, including abdominal distention and respiratory distress^8,10-12. One reported case presented as a diaphragmatic hernia¹³. A neonatal ultrasound examination may be performed to confirm the diagnosis and to provide a baseline for future follow-up and management.

Table 3: Complications of non-parasitic simple hepatic cysts.

Therapy and prognosis

Most simple cysts will remain  asymptomatic. Occasionally, some may cause complications which require treatment. Possible complications are listed in Table 3^14,15. The majority of reported cases involve either obstruction of the biliary system or symptoms due to the mass effect of the cyst. Generally, this occurs with very large cysts exceeding 10 cm in diameter. Other presentations, including infection, hemorrhage, or rupture, are less common^16-19. There has been one reported case of IVC obstruction secondary to a simple hepatic cyst¹⁵. Very rarely, squamous cell carcinoma may arise in a simple cyst. Prognosis in this case is grave, as the carcinoma is usually already in an advanced stage when detected^20,21. Percutaneous aspiration under ultrasound guidance can yield information regarding the nature of a cystic hepatic lesion; however, aspiration of a simple cyst will generally result in reaccumulation of cyst fluid. Instillation of sclerosing agents such as ethanol or minocycline after cyst aspiration has been successful in preventing reaccumulation of cyst fluid^22,23. Surgical intervention is required for neoplastic cysts and refractory simple cysts. If the cyst contains bilious material, then a Roux-en-Y limb is created for drainage. More commonly, serous cysts may be treated by simply unroofing the cyst so that it drains into the peritoneal cavity^24,25. Successful laparoscopic treatment has been reported^26,27.

References

1. Withers CE, Wilson SR: Liver cyst. In Diagnostic Ultrasound, Mosby Year Book, St. Louis, 1991, pp. 53-55.

2. Thrasher S, Adelman S, Chang CH: Hepatic cyst associated with PeutzJeghers syndrome. Arch Pathol Lab Med 1990; 114: 1278-80.

3. Geist DC: Solitary nonparasitic cyst of the liver. Arch Surg 1955; 71: 867-80.

4. Terada T, Nakanuma Y, Ohta T, et al: Mucinhistochemical and immunohistochemical profiles of epithelial cells of several types of hepatic cysts. Virchows Arch A Pathol Anat Histopathol 1991; 419:499-504.

5. Jojart G, Verebely T: Primary neonatal liver cyst. Orv Hetil 1992; 133:210-12.

6. Baunin C, Mechinaud Puget C, Fajadet P, et al. Management of a biliary cyst disclosed prenatally. Apropos of 2 cases. Chir Pediatr 1990; 31:1603.

7. Dyon JF, Sabatier E, Jouk PS, et al.: Prenatal diagnostic imaging of abdominal cysts. Report of 9 cases. Pediatrie 1990; 45:857-68.

8. Quillin SP, McAlister WH: Congenital solitary nonparasitic cyst of the liver in a newborn. Pediatr Radiol 1992; 22:543-4.

9. Seidman JD, YaleLoehr AJ, Beaver B et al.: Alimentary duplication presenting as an hepatic cyst in a neonate. Am J Surg Pathol 1991 Jul; 15:695-8.

10. Heloury Y, Bouvier S, Nomballais MF, et al.: Hepatic cyst in a newborn infant. Pediatrie 1991; 46:593-5.

11. Athey PA, Lauderman JA, King VE: Massive congenital solitary nonparasitic cyst of the liver in infancy. J Ultrasound Med 1986; 5: 585-7.

12. Merine D, Nussbaum AR, Sanders RC: Solitary nonparasitic hepatic cyst causing abdominal distention and respiratory distress in a newborn. J Pediatr Surg 1990; 25: 349-50.

13. Chu DY, Olson AL, Mishalany HG: Congenital liver cyst presenting as congenital diaphragmatic hernia. J Pediatr Surg 1986; 21: 897-9.

14. Forbes A, MurrayLyon IM, Cystic disease of the liver and biliary tract. Gut 1991; suppl: S,116-22.

15. Benchimol D, Mouroux J, Le Roux Y, et al: Complicated solitary bilious cysts. J Chir 1991; 128:221-5.

16. Schwed DA, Edoga JK, Stein LB: Biliary obstruction due to spontaneous hemorrhage into benign hepatic cyst. J Clin Gastroenterol 1993; 16:846.

17. Spivey JR, Garrido JA, Reddy KR, et al.: ERCP documentation of obstructive jaundice caused by a a solitary, centrally located, benign hepatic cyst. Gastrointest Endosc 1990; 36:521-3.

18. Karia M, Dasgupta TK, Sharma V, Chaudhuri MM, Mazumder DN. Symptomatic solitary giant congenital cysts of the liver. Indian J Gastroenterol 1992; 11:136-8.

19. Lai EC, Wong J: Symptomatic nonparasitic cysts of the liver. World J Surg 1990; 14:452-6.

20. Nieweg O, Slooff MJ, Grond J: A case of primary squamous cell carcinoma of the liver arising in a solitary cyst. HPB Surg 1992; 5:203-8.

21. Pliskin A, Cualing H, Stenger RJ: Primary squamous cell carcinoma originating in congenital cysts of the liver. Report of a case and review of the literature. Arch Pathol Lab Med 1992; 116:105-7.

22. Furuta T, Yoshida Y, Saku M, et al: Treatment of symptomatic nonparasitic liver cystssurgical treatment versus alcohol injection therapy. HPB Surg 1990; 2:269-79.

23. Hagiwara H, Kasahara A, Hayashi N, et al: Successful treatment of a hepatic cyst by oneshot instillation of minocycline chloride. Gastroenterology 1992; 103:675-7.

24. Sanchez H, Gagner M, Rossi RL, et al: Surgical management of nonparasitic cystic liver disease. Am J Surg 1991; 161:113-9.

25. Nelson J, Davidson D, McKittrick JE: Simple surgical treatment of nonparasitic hepatic cysts. Am Surg 1992; 58:755-7.

26. Lange V, Meyer G, Rau H, et al: Minimally invasive interventions in solitary liver cysts. Chirurg 1992; 63:349-52.

27. PatersonBrown S, Garden OJ: Laser assisted laparoscopic excision of liver cyst. Br J Surg 1991; 78:104-7.

28. Schramm T, Schmoltz A, Gloning KP, et al: Sonographische diagnostik fetaler leberzysten. Geburtshilfe Frauenheilkd 47: 124-7, 1987

29. Chung WM: Antenatal detection of hepatic cyst. JCU 14:217-9,normal 1986.