In symptomatic. Furthermore, only 10%–40% of congenital cysts are

In 1856,
Mickel described the first congenital solitary nonparasitic hepatic cyst in an
adult.(22, 35) Between 1856 and 1995, more than 400 cases
have been reported in the pediatric literature, among which only 5% involve
infants less than 2 years of age.(22, 35) True nonparasitic congenital hepatic cysts
have a reported overall prevalence ranging between 0.1% and 2.5%,(18, 36) although noninvasive imaging has shown that
asymptomatic hepatic cysts are likely more common in the general population
than originally believed.(35, 37) Calculation of the precise frequency of
congenital hepatic cysts in the pediatric population is difficult, because the
lesions rarely produce symptoms and so they are usually not detected until
adulthood after they become symptomatic. Furthermore, only 10%–40% of
congenital cysts are estimated to become symptomatic.(35, 38) Quiescent lesions are usually discovered as an
incidental radiographic, intraoperative, or autopsy finding. In a retrospective
review at Boston Children’s Hospital, Boston, MA, USA, in which 30 cases of
congenital nonparasitic hepatic cysts were reviewed in children less than 8
years of age, only 40% of children were symptomatic from abdominal distension
whereas 60% of lesions were incidental findings at autopsy.(18, 35)

 When detected(35) in adulthood, hepatic cysts are mainly found
between 20 and 50 years of age with a median age at presentation of 48 years.(39, 40) The female-to-male ratio is 5:1.(18, 35)

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Classification

The term
hepatic cyst commonly refers to solitary nonparasitic cysts of the liver, which
known as simple cysts.(1, 2)
However, many other cystic lesions might be distinguished from true simple
cysts. Cystic lesions of the liver include Simple cysts, multiple cysts arising
in the setting of polycystic liver disease (PCLD), parasitic or hydatid
(echinococcal) cysts, cystic tumors and abscesses. Nonparasitic liver cysts are
classified as solitary cyst or multiple cysts. Although multiple cysts may be
associated with congenital polycystic disease of the kidney or dilatation of
the bile ducts (Caroli’s disease), SLCs never accompany other organ cysts.(3, 4, 32) Solitary
liver cyst is a benign liver lesion. It is seen four times more common in
females.(3, 4, 32, 41) Further,
it can be classified as simple solitary liver cyst (SLC) and solitary
intrahepatic biliary cyst (SIBC).(4, 32, 42) The
etiology of SLC is not known. SLC has been hypothesized that obstruction of
aberrant bile ducts from infection or as a result of a vascular disruption
during the fetal period can be a cause.(32, 41-44)
Alternatively, overdeveloped intralobular bile ducts may become dilated with
time and result in an Solitary liver cyst.(32, 45) However, none of these etiologies can explain
the Solitary intrahepatic biliary cyst in our patient. Although, the cyst was
confirmed to be a true biliary cyst located close to the main intrahepatic bile
ducts. It has small canalicular connections with the main intrahepatic bile
ducts. Simple cysts reported for most of the prenatally detected and postnatally
diagnosed solitary lesions. They may be underrepresented in this series because
some asymptomatic simple cysts would not have been referred to our unit. From
aberrant bile ducts, simple cysts are generally thought to be developed,(23-25) but an
origin from intrahepatic peribiliary glands has also been suggested.(26, 27)

Hepatic
cysts may be classified broadly into two major categories – congenital or
acquired.(35, 46, 47) which
can also be categorized on the basis of history, symptoms, and radiographic
appearance. Congenital liver cysts arise from abnormal development of the
intra- or extrahepatic biliary tree. They are solitary simple or multiple
polycystic.(35, 48) Unlike
polycystic liver disease, simple hepatic cysts do not have a genetic basis, and
there is no association with renal, splenic, pancreatic, or lung cysts.(18, 35) Acquired liver cysts are parasitic
(infectious) or nonparasitic (post-traumatic and neoplastic).(35, 46) Parasitic cysts are usually hydatid cysts which
results from infection with Echinococcus granulosus. Most acquired nonparasitic
hepatic cysts are post-traumatic pseudocysts.(35, 46) as shown in table 4.

Table
4.  Solitary liver cysts in children

Congenital

Acquired

Simple

Parasitic
(hydatid)

Mesenchymal
hamartoma

Posttraumatic

Intrahepatic
choledochal cyst

Neoplastic:
cystadenoma, sarcoma, teratoma

Ciliated
hepatic foregut cyst

Biliary
cysts (biliary atresia post Kasai, traumatic)

Epidermoid
cyst

Abscess
(eg, pyogenic, amoebic)

Lymphangioma

 

 

Small
asymptomatic liver cysts are considered benign, but they should be followed for
growth and the possibility of malignant degeneration.(35, 37)

Pathophysiology

Congenital
liver cysts arise from the biliary tree and more specifically, they are
believed to originate from enlargement of congenital aberrant biliary ducts. Congenital
liver cysts are usually lined with biliary columnar epithelium, but there may
be present of squamous or cuboidal cells.(35, 46) In spite of their biliary origin, only 25% of
cysts have a connection with the biliary tree,(35, 46) which suggest that the underlying etiology may
be progressive dilatation of biliary microhamartomas which is secondary to
failure of normal connections with the biliary tree. Differentiation between
lesions that communicate with the biliary system and those that do not is
essential for deciding appropriate management. Although the exact etiology may
not be clear, the overall pathogenesis involves a congenital malformation with
accompanying inflammation and fluid accumulation from secreting biliary
epithelium.(18, 35) Therefore, destruction of the epithelium is
the basis for treating these lesions. The most common anatomic location is
segment 5 of the right hepatic lobe,(35, 49) with right lobe lesions reported in the literature
twice as long as left.(18, 35) Unilocular cysts are much more common than
multilocular cysts. The multilocular type is extremely rare in children.(18, 35) Cysts may be solitary, multiple, or diffuse
throughout the liver (polycystic disease). Despite, they usually contain clear
fluid with variable amounts of protein, cholesterol, blood cells, mucin, and
epithelial cells.(35, 49)

 

Clinical
presentation

Solitary
liver cysts SLCs are typically asymptomatic and their symptoms do not
manifest until patients are in their forties or fifties.(3, 4) The anteroinferior segment of the right hepatic
lobe is the most common site (3, 4) of SLC.(3, 4, 41) The pathophysiology
of simple liver cysts is mostly related to the continuous secretion of fluid by
epithelial cells. In spite of this, only 10%–15% of liver cysts cause symptoms.(35, 38) Most lesions are not symptomatic and
discovered incidentally in adulthood. Abdominal discomfort and right upper
quadrant pain are commonly the first presenting symptoms in adults, but
symptoms can stay inactive as a consequence of the low internal pressure of the
cysts.(35, 49)

In the
pediatric population, a hepatic cyst may be first discovered on prenatal
imaging. In children, progressive abdominal distension is the most common
presenting sign.(18, 22, 35, 39, 50)
Associated symptoms are related to the space occupying effect of the lesion on
adjacent viscera and include upper abdominal and right shoulder pain, nausea, vomiting,
gastroesophageal reflux, early hungry, difficulty in breathing, and respiratory
distress.(35, 50, 51)
Pressure on the vertebral column may cause lumbar pain, and pressure on the
bladder may cause urinary frequency.(35, 38) Most cysts do not occupy biliary or vascular
structures, but they may cause obstruction or compression atrophy.(35, 52) Infrequently, the cyst exerts pressure on the
liver parenchyma or porta hepatis,(35, 53) which results in obstructive jaundice,(35, 37, 38, 46)
cholangitis,(35, 36) or portal hypertension.(35, 38) Except for patients who present with
obstructive jaundice, liver function tests are usually within normal limit.(35, 37) Liver failure has been reported, but it is
extremely rare.(35, 53) Urgent or emergent surgical resection is
rarely necessary, and it is limited to acute complications, which includes
infection, bile leak, rupture, peritonitis, intra-cystic hemorrhage and torsion.(18, 35, 38, 52)

An SLC
is usually unilocular and lined by cuboidal or columnar epithelium with no connection
to the biliary tree.(4, 41) The outer layer of the cyst wall is composed
of collagen, muscle fibers, bile ducts, and liver cells, which are separated
from the epithelial lining by vascular tissue.(4, 43) The cystic fluid may be clear, brown, or
occasionally bilious.(4, 43)

The
differential diagnosis included a mesenteric cyst, lymphatic malformation,
hepatic malignancies, biliary atresia, choledochal cyst, or liver cyst.
Accurate diagnosis is made primarily by radiographic studies often requiring
histopathological verification. On ultrasonography, a SLC appears as an
anechoic unilocular fluid-filled space with a posterior acoustic enhancement.(3, 4) SLC typically cannot be differentiated from
cystic malignant tumors on radiological studies; tissue diagnosis is necessary,
even in asymptomatic patients.(3, 4) Histological criteria for an SLC include an
outer layer of thin dense fibrous tissue, an inner epithelial lining (cuboidal
or columnar), and lack of mesenchymal stroma or cellular atypia(4, 54) as in our case.

Perioperative
cholangiography should be performed in all cases to detect connections between the
SLC and the biliary tree.(4, 41) The communication between the cyst and the
biliary tree was seen on cholangiography as in our case. The postoperative
course may be complicated by infection, cholangitis, and recurrence.(4, 41)

Treatment
options

Treatment
of congenital solitary liver cyst is indicated for symptoms including abdominal
pain, nausea, vomiting, obstruction, and complications like perforation,
secondary infection, internal bleeding, torsion, and to rule out malignancy.
Nonsurgical and surgical options are available. Nonsurgical options include
serial observation, and aspiration with or without sclerosis. Surgical options
include enucleation that is cystectomy, fenestration that is unroofing,
internal drainage, hepatic resection, and, rarely, hepatic transplantation.
Celebi et al. performed a 10-year retrospective review of congenital liver
cysts in their institution.(35, 55) Of the 67 pediatric cases diagnosed prenatally
or postnatally, in which, 10 underwent open surgery with the main indication
being a complication of the cyst or increasing size of the cyst, causing
symptoms such as abdominal pain due to mass effect. Four patients underwent
open fenestration, five underwent total enucleation, and one underwent a
partial hepatectomy. Intraoperative cholangiogram was performed in cases where there
was preoperative evidence of biliary communication.(35, 55)

Nonsurgical
therapy

Liver
cysts were conventionally diagnosed when they were large enough to become
apparent as an abdominal mass, or as an incidental finding during laparotomy or
autopsy. Extensive use of improved imaging has led to increased detection of
incidental lesions.(18, 35) The patients which are asymptomatic with small
lesions do not necessarily require treatment, as the possibility of complications
is believed to be lower than the risk associated with treatment.(35, 53) Although considered benign, untreated cysts might
be followed with a serial ultrasound or CT scan as consequence of the small risk
of malignant transformation.(35, 37) Treatment of a liver cyst requires excision of
the fluidsecreting epithelium. For this reason, simple percutaneous needle
aspiration is almost universally ineffective and is associated with 100%
recurrence.(35, 38, 40, 53, 56) As a
result, simple aspiration has been accepted as definitive therapy. It is only
appropriate in select circumstances as a temporizing measure to relieve severe
or life-threatening symptoms, for example of, respiratory distress in a newborn,
or when definitive treatment is associated with high operative risk. Several reports
of sclerotherapy in the adult population have shown variable results,(35, 38) despite the fact that aspiration with
sclerosis yields better results than aspiration alone.(35, 48)
Sclerotherapy is less invasive and is associated with fewer complications than
surgical intervention, but it is associated with a higher recurrence rate.(35, 53, 56) In a
study of 23 adults with symptomatic nonparasitic hepatic cysts, 100% (6/6) of
those who underwent sclerotherapy had a recurrence of their cyst, whereas 25%
(2/8) of the patients’ status postlaparoscopic fenestration had a recurrence.(35, 57) There are few reports of congenital liver
cysts treated with sclerotherapy in the pediatric population.(35, 58) Intracystic ethanol injection was used in at
least one newborn infant with a rapidly enlarging liver cyst, with no evidence
of recurrence at 7-year follow-up.(35, 59) Caution must be used, as commonly used
sclerosing agents (e.g., ethanol) can cause alcohol intoxication and
irreversible sclerosing cholangitis.(35, 48)

Surgical
therapy

Surgical
intervention is retained for significant abdominal or respiratory symptoms due
to cyst growth, acute complications, or neoplastic growth. Surgical options consist
of fenestration, enucleation, internal drainage, resection, and rarely, liver
transplantation. The basic principles are to completely remove or destroy the
cyst epithelium, and to provide a mechanism for drainage of the cyst fluid. If
the cyst communicates with the biliary tree, an internal drainage procedure is
necessary. This procedure is also known as cystgastrostomy or cystjejunostomy.
If the cyst does not communicate with the biliary system, free drainage into
the peritoneal cavity is acceptable, because the fluid is reabsorbed by the
peritoneum. Total excision should be attempted for easily accessible solitary
liver cysts (SLCs) and enucleating may also be chosen for small cysts.(4, 43) When total excision is not possible, partial
excision has been recommended.(4, 41) As much of the cyst wall as possible should be
excised, taking care not to damage vital structures.(4, 43) Internal drainage of the cyst via
cystoenterostomy or Roux-en-Y hepaticojejunostomy has been recommended when the
biliary system drains into the cyst and bile drainage into the enteric circulation
cannot be obtained.(4, 41) Biliary reconstruction is required in several
clinical situations, including resection of biliary malignancies, benign
biliary strictures, intraoperative injury, and liver transplantation.
Bilioenteric anastomosis using the Roux-en-Y jejunum limb is a well-established
approach.(4, 60) Reconstruction using the jejunum allows for
safe and permissive anastomosis with infrequent postoperative bile leakage even
when the anastomoses involve small intrahepatic branches(4, 61) as in our case. Techniques for surgical
therapy have largely been adopted from the adult population.

In 1968,
Lin et al. described the technique of wide fenestration for polycystic liver
disease in two pediatric and three adult patients.(35, 59) meanwhile that time, the technique has also
been applied successfully by many surgeons to treat simple liver cysts.(35, 37) Wide fenestration consists of creating a large
opening or window on the nonparenchymal side of the cyst to allow free drainage
of fluid into the abdominal cavity as in our patient 3. Although the cyst wall
continues to secrete, the peritoneal lining reabsorbs the fluid. Symptomatic
relief is achieved, because fluid is no longer accumulating within the enclosed
space of the cyst wall. Since fenestration does not involve dissection of
hepatic parenchyma, it is associated with lower morbidity than enucleation. Fenestration
has a recurrence rate ranging from 0% to 38%.(35, 38) Adding omentoplasty and oversewing the margins
with a running suture appear to reduce the recurrence rate to 0%–14%.(35, 38) Enucleation (complete cyst excision) involves
complete removal of the cyst epithelial lining, often with a small rim of the
liver, resulting in complete cure. Complete cyst excision is often considered
the treatment of choice for congenital hepatic cysts found in adults.(35, 56) Recurrence after partial resection is related
to the remaining epithelium within the cyst wall. Even a small amount of
residual epithelium can lead to recurrence. Although enucleation yields the
lowest recurrence rate (4%), morbidity can be high, as the operation requires dissection
of liver parenchyma with the associated risks of hemorrhage and bile leak.(35, 62)

In 1991,
Z’Graggen reported the first laparoscopic fenestration of a solitary
nonparasitic hepatic cyst in an adult patient.(35, 63) Since that time, others have reported use of
the laparoscopic technique, but mainly in case reports or small series that
provides little data on long-term outcome.(22, 35, 37, 50)

Ardito
et al. treated 47 adult patients diagnosed with nonparasitic hepatic cysts with
laparoscopic fenestration due to either a symptomatic presentation or an
uncertain diagnosis. None of the cases required conversion to open surgery. The
overall recurrence rate was 14.9% (seven patients), yet only 4.3% (two
patients) presented with recurrent symptoms that necessitated surgical
management. There was no recorded postoperative mortality or morbidity, and
follow-up ranged from 24 to 142 months.(35, 64) Although no randomized controlled trials are
available to make definitive recommendations on laparoscopic versus open
therapy, available data suggest that symptom relief and recurrence rate after
laparoscopic fenestration are similar to the open approach, but with lower morbidity
and mortality.(35, 38) Also, laparoscopic fenestration has been shown
to result in less pain, decreased length of hospital stay, and earlier return
to normal activity when compared with open fenestration.(35, 56) As with the open approach, recurrence has been
attributed to failure to ablate the cyst lining, and failure to resect enough cyst
wall to allow for adequate drainage.(35, 65) Although recurrence rates and long-term
results are not known, laparoscopic fenestration is considered the standard of
care for solitary nonparasitic hepatic cysts located on the liver surface.(35, 38, 53) There
are limited accounts of laparoscopy being used for treatment of hepatic cysts
in pediatric patients, especially in neonates, due to the limited experience of
laparoscopic surgery in this patient population.(35, 40) Nordin et al. reviewed all the case reports of
neonatal congenital hepatic cysts in the literature and found that five out of
the eight cases were managed laparoscopically, with two undergoing complete cyst
excision and three undergoing fenestration. Of the reviewed cases, none
reported any postoperative complications or recurrence.(35, 66) Laparoscopic surgery is associated with decreased
bleeding, decreased risk of ileus, shorter hospital stay, early mobilization, and
improved cosmesis.(35, 62, 67, 68) Relative
contraindications to the laparoscopic approach are lesions located deep inside
the hepatic parenchyma and those associated with hilar structures, as these
increase the risk of extensive hemorrhage or damage to bile ducts.(35, 37, 48) Laparoscopy
should be reserved for lesions located in accessible areas, namely the anterior
and lateral segments.(35, 48) In the
pediatric population, especially, one must consider the small working space in
the abdominal cavity and the technical challenges this can present
laparoscopically. Open surgical management should be reserved for cysts that
are not accessible by laparoscopy.(35, 46) Hepatic resection is appropriate for giant cysts,
complex recurrent cysts, polycystic disease, diffuse liver involvement, and
malignancy.(35, 46, 48) Hepatic
transplantation is rarely performed for hepatic cyst disease, but it is
reserved for giant cysts or polycystic disease in which resection would
compromise hepatic function.