2.3 Outcome and Follow-up
The patient had good postoperative recovery after postoperative
intensive care management for COPD exacerbation. The histopathological
evaluation of the resected specimen revealed variable-sized cysts lined
with columnar cells having basal nucleus and apical mucin. The cyst
contained mucinous material. The surrounding liver tissue showed
fibrosis encircling hepatocytes forming parenchymal nodules but lacked
ovarian-like stroma. (Figure 2) The patient is doing well in the
follow-up of 1 year with no recurrence.
3 Discussion
The cyst leading to atrophy of the left lobe of the liver, radiological
communication of dilated intrahepatic bile ducts within, and absence of
ovarian-like stroma makes our case unique. World Health Organisation
(WHO) in 2010 proposed uniform terminology of mucinous cystic neoplasm
in the presence of ovarian-like stroma (OS) or intraductal papillary
mucinous neoplasm of bile duct (IPMN-B) in the presence of biliary tree
communication.2 However, the presence of OS and
demonstration of bile duct communication is not present in all
cases.3 The literature does not clarify whether
cystadenoma without OS is a discrete entity or IPMN-B where biliary
communication could not be established. The prevalence of these cysts
compared to those with OS is lower4 but few studies
have shown equal prevalence as well.5 Most IPMN-B
cases have been described as tubular or fusiform dilatation of bile
ducts similar to IPMN of the pancreas.6 The rate of
malignancy in IPMN-B (60% - 70%) is higher than that of the pancreatic
counterpart of IPMN (23%-30%).7,8 The presence of
mural nodules suggesting malignancy is commonly present except in benign
cases.7 The stage of malignancy in IPMN-B is however
less advanced.1
Cystic IPMN-B is an uncommon variant as in the index case resembling
branch duct IPMN of the pancreas.6 These cysts have
been thought to arise from prebiliary glands located within the wall or
scattered in the surrounding connective tissue of the larger bile
duct.9 It has equal sex predilection and peaks in the
sixth decade.1,10 The cystic IPMN-B is frequently
associated with mural nodules and bile duct dilatation distal to the
cyst.7 This is attributed to mucus from cysts in the
bile duct leading to obstruction and dilatation, which in the long run
could lead to liver atrophy as in the index case. Mucobilia may result
in transient biliary obstruction or recurrent
cholangitis.1 The risk factors are shown to be
hepatolithiasis, Clonorchis infections, etc.11Although biliary communication is a key feature, CECT or magnetic
resonance imaging cannot always demonstrate luminal communication,
probably due to narrow communications.12 However, the
biliary communication in the background of the atrophic liver was well
demonstrated by a CT scan in the index case. Cyst fluid CEA in the index
case was normal. The exact correlation of CEA to cystic IPMN-B is
scarcely described in literature, but higher fluid CEA has been
associated with cystadenocarcinoma.13
All Cystic IPMN-B requires resections, preferably with intraoperative
cholangiogram to demonstrate biliary communication and to rule out mucus
plugs in the bile duct. Preoperative endoscopic retrograde
cholangiography or intraoperative cholangiography (IOC) is more reliable
as macroscopic examination is often accurate.14 IOC
was not used in the index case due to logistic issues. Although the
index case had no malignant foci, most of the cases have malignant foci
which warrant formal hepatectomy in all cases. Additionally,
extrahepatic bile duct resection and lymph node sampling may also be
required in case of malignant cysts. The prognosis after resection is
good compared to intrahepatic or hilar cholangiocarcinoma with 5-year
survival of 60% to 80%.10 The columnar cells and
MUC1 expression adversely impact survival.1,10