Cuillier F, MD*, Lemaire P, MD**, Deshayes M, MD**

* Department of Gynecology, Félix Guyon' Hospital, ** Sonographer, Moufia'street, Saint-Denis, Ile de la Réunion, France

The prenatal diagnosis of hepatic cysts  is uncommon ¹. The hepatic cyst is the second most common benign hepatic lesion, with a prevalence of  2.5 % of the general population ². Hepatic cysts are frequently non-parasitic, simple, solitary or unilocular, fluid-filled space within the liver with a fibrous capsule and lined by cuboid 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. Nevertheless, only 6 cases have been described in fetuses. It is most frequent with girl ¹.

Case report

This is a 28-year-old woman, gravid 4, para 3, that was initially scanned at 12 weeks. A single viable fetus with a CRL of 52 mm (appropriate for this gestational age) was seen. The nuchal translucency measurement (1mm) and the morphology were normal. The couple was healthy, nonconsanguineous and had no relevant past history. Triple serum screening was performed (normal) at 16 weeks and at 24 weeks no abnormalities were seen (female fetus).

At 33 weeks, another scan revealed a cyst in the right low quadrant (36 X 30 mm) distinct from the gallbladder and stomach. Color Doppler imaging showed no relationship between the cyst and the portal vein and hepatic or kidney arteries. Color Doppler ultrasound revealed no flow within the mass.

A liver cyst was suspected. A digestive duplication or an ovarian cyst were other hypothesis. The other differential diagnosis included choledochal cyst, biliary atresia, and mesenteric cyst. The latter ultrasound scans demonstrated that the localized right-sided non-septate lesion, had the same size at 38 weeks (37 X 35 mm). The patient delivered at 38 weeks (girl, 2800g).

At day three, echography confirmed a cyst (40 mm) bellow the liver, but independent from the gall-bladder and the biliary tract. The internal and external biliary tract were not dilated. The fetal ultrasound examination was normal except for the finding of this isolated cyst of the anterior segment of the right lobe of the liver. The patient underwent a laparotomy with excision of a large cystic mass, situated near the inferior part of the liver, without gallbladder contact and biliary tract. The interior of the cyst was translucide with a fine membrane. The post operative course was uneventful and the child recovered. Histological examination of the cyst surprisingly showed a lymphangioma.

Doppler examination shows the abnormally right cyst (30 mm X 38 mm) at 34 weeks

Transverse sonographic examination at the level of the stomach shows an abnormally right cyst (12 mm) in the upper fetal abdomen at 34 weeks.

3D view showing the non-septate abdominal cyst at 34 weeks

Synonyms: Liver hygroma, lymphangiomatosis or lymphangio-endothelioma.

Prevalence: Lymphangiomas occur in 1 per 20.000 pediatric admissions with a same sex distribution³. Once thought to be rare, simple hepatic cyst are now routinely detected in adults with CT, MRI and ultrasound⁵. 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 affected¹. Congenital hepatic cysts are extremely rare, only six cases of prenatally diagnosed liver cyst have been reported in the recent literature.

Recurrence risk is not known.

Pathogenesis: It is believed that lymphangioma result from a developmental defect in the lymphatic pathway, which usually develop from the 6  weeks, leading to proximal dilatation of afferent channels. Others theory includes failure of the embryonic lymph sacs to re-establish communication with the venous system or aberrant budding of primordial sac. So lymphangioma is one of the developmental abnormalities of the lymphoid system which occurs at the site of the lymphatic-venous connections. Cuboid epithelial lining and location within the portal triad suggest aberrant development of intrahepatic bile ducts with no connection to the normal biliary drainage.

Classification: Lymphangioma are histologically divided into three categories:

• lymphangioma simplex,
• cavernous lymphangioma and
• cystic lymphangioma⁵.

Lymphangiomas can occur a variety of anatomical locations. The most common area is the neck (75 %), followed by the axillary region (20 %), retroperitoneum and abdominal viscera (2 %), limbs and bones (2 %) and cervico-mediastinum (1 %)3. Abdominal lymphangiomas occur most commonly in the mesentery of the small bowel. On those located below the diaphragm, most are found in the retroperitoneum, followed by the mesentery⁵.While the cause is not known, the classic pathological 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 disease.

Differential diagnosis: Dermoid cyst, lymphatic cyst, enteric duplication, duodenal atresia, choledochal cyst, Carolïs disease, pancreatic pseudocyst, hydronephrosis, renal cyst, cystic renal dysplasia, ovarian cysts, urachal cyst, adrenal cyst, mesenteric or omental cyst, splenic cyst, cystic dilatation of intrahepatic bile ducts, bowel duplication, and cystic structures within other abdominal structures. There may be some evidence linking such cysts with tuberous sclerosis and Peutz-Jeghers syndrome, but this is uncertain ^6-7.

If the cyst is localized into the liver, the differential diagnosis includes essentially dermoid cyst, lymphatic cyst and choledochal cysts. We must think about cystic dilatation of biliary ducts with Caroli’s disease (but in this case, cysts are usually multiple), polycystic liver disease (usually multiple too) and enteric duplication ^8-9.

In our case, initially we essentially believe that it was a bowel duplication, a liver cyst or an ovary cyst. We should have made a MRI. Ultrafast MRI scans further depicted a detailed anatomical relationship of the cyst to the liver, gallbladder and biliary cyst. Lymphangiomas classically have a thin wall, often have multiple septations and can be readily distinguished from the liver, spleen, pancreas and kidney. Our case was detected at 32 weeks and scans show an enlarging cyst mass but without multiples septa, which in retrospect was unclassical of abdominal lymphangioma². Experiences from previously published studies demonstrate the tendency of these lesions to enlarge rapidly and cause abdominal obstruction especially perinatally, but it was not the case here¹⁰.

Lymphangioma are benign tumors of the lymphatic system, with the potential for expansion and infiltration into surrounding structures3. Prenatal diagnosis is not uncommon. Early diagnosis facilitates proper planning and prompt postnatal resuscitation, which improves survival. Nonetheless, lymphangioma can lead to complications at birth or shortly after birth4. In this article we described the antenatal discover of a hepatic cyst, which wasin fact a lymphangioma.

Implications for target examinations: Prenatal diagnosis of hepatic cyst has been rarely described in the literature. Sonographic findings can be thick wall cyst or hypoechogenic mass located or with close relation to the fetal liver. Absent flood flow is observed.  In the preoperative assessment, MRI should been used to accurately demonstrate the presence extent and types of cysts. Additionally, MRI has the advantages of rapid delineation of tissue borders and easy selection of imaging planes. Nevertheless 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.

Associated anomalies: Tuberous sclerosis, rare, may lead to cysts within the liver and kidneys. Peutz-Jeghers syndrome and omphalocele have also been reported in association with a simple hepatci cyst. Skin edema, ascites, hydrops and polyhydramnios and  placental chorioangioma can be associated⁶.

Prognosis: When a fetal lymphangiomas is diagnosed in the fetal period, the overall diagnosis is poor with a rage mortality ranges from 50 to 100%. Because of the paucity of available data, it is uncertain whether abdominal lymphangiomas carry a significant risk for aneuploidy. Nevertheless offering karyotype is recommended to the parents of affected fetus. The prognosis is benign if the karyotype is normal and hydrops is absent. These cysts growth slowly and rare complications may be due to their enlargement, infection, or hemorrhage.

Treatment: A neonatal ultrasound examination may be performed to confirm the diagnosis and to provide a baseline for future follow-up and management. After birth, the principal complication may be jaundice, due to obstruction of biliary system. Sometimes pain due to infection or hemorrhage. Generally, this occurs with very large hepatic cyst exceeding 10 cm in diameter. Infection, hemorrhage or rupture are less common, but can ocurr during delivery. Hepatomegaly is rare, but can produce IVC obstruction. Neoplastic degeneration are not common.

Although there are some reports of cystic lymphangioma in other location of the body treated with intra-uterine aspirations, local sclerotherapy or injection of fibrin glue, the definitive treatment consist in complete postnatal surgical resection of the lesion depending on the size of the tumor. Percutaneous aspiration under ultrasound guidance can yield information regarding the nature of the lesion. However, aspiration of a simple cyst will generally result in reaccumulation of cyst fluid. So instillation of sclerosing agents such as ethanol or minocycline after cyst aspiration has been successful in preventing reaccumulation of fluid. Surgical intervention is required for refractory simple or large hepatic cysts. If the cyst contains bilious material, then a Roux-en-Y limb is created for drainage. More commonly, serous hepatic cyst may be treated by simply unroofing the cyst so that it drains into the peritoneal cavity. Successful laparoscopic treatment has been reported. Twelve of reported prenatally detected HC were excised in the neonatal period. So only limited experience is available concerning the surgical treatment of symptomatic cysts. During surgery, communication with extra hepatic and intrahepatic biliary system has to be ruled out by cholangiography. Total excision or enucleation seems to be the treatment of choice. If this is not possible, partial excision with marsupialization of the cyst wall is recommended. Last point, there seems to be no argument in favor of prophylactic cesarean section in case of hepatic cyst. Indeed reports on dystocia due to hepatic cyst are exceptional.

Conclusion
The diagnosis of hepatic cyst is particularly rare, but the diagnosis of lymphangioma is more difficult. So RMI seems usefull  when we suspected of hepatic cyst. Iis important to perform this diagnosis to avoid complications.

References

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