Keywords
choledochal cyst - cystic biliary atresia - atretic variant
Introduction
Biliary atresia and choledochal cyst (CC) are two of the most common causes of obstructive
jaundice in infants. Infantile variant of CC can mimic cystic biliary atresia in clinical
presentation leading to diagnostic dilemma.[1]
[2]
[3] Biliary atresia associated with CC is also reported in literature. Here, we present
an unusual case of CC that does not fit into the current classification of CCs, and
can be called an atretic variant of CC.
Case Report
A 73-day-old boy was brought to our hospital with the complaint of progressively increasing
jaundice. This boy was conceived by in vitro fertilization, the second among twins,
through cesarean section. Antenatal check-ups were unremarkable. Until 15 days of
life, this boy was healthy, taking breastfeeds well and passing yellow/greenish stool.
Later he developed symptoms: passing clay colored stool, yellowish discoloration of
sclera and body. Initial evaluation done in other hospitals revealed cholestatic jaundice.
Finally, when the patient was brought to our hospital, he was deeply icteric. The
patient was underweight compared with his elder twin. Liver, with smooth margin and
soft consistency, was palpable 3 cm below costal margin. Patient had elevated liver
enzymes (AST–64 U/L, ALT–129 U/L, ALP–1,000 U/L) and hyperbilirubinemia (Total bilirubin–8.74 mg
/dL, direct–4.9 mg/dL). Gamma glutamyl transpeptidase (GGT) was elevated (1,006 U/L).
Hemogram, PT/INR, C-reactive protein, and thyroid profile were normal.
Ultrasonography of abdomen revealed dilated intrahepatic biliary radicles with dilated
common bile duct (CBD) till mid part of CBD. A hyperechoic soft calculus without distal
acoustic shadowing was seen in the lumen of distal intrapancreatic CBD. Gall bladder
(GB) was normal in size with well-defined walls ([Fig. 1]).
Fig. 1 (a, b, and c) Ultrasound images showing a well-defined gall bladder (thin yellow arrow), dilated
common bile duct (CBD; thick yellow arrow), an echogenic calculus in lower CBD (white
arrow).
Further, Magnetic resonance cholangiopancreatographic (MRCP) imaging revealed tubular
cystic dilatation of common hepatic duct and confirmed intrahepatic biliary radicles
dilatation. Cystic duct was unusually draining quite distally. Abrupt narrowing was
seen at the junction of common hepatic duct (CHD) and CBD which was hypothesized to
be due to a possible stricture at this level. A calculus (8 mm) was evident in the
lower CBD extending into intrapancreatic part of CBD. Cystic duct was draining just
above the calculus ([Figs. 2] and [3]). Main pancreatic duct was not dilated.
Fig. 2 MRI images of a 3-month-old infant with cholestatic jaundice. (a, b) 2D MRCP showing cystic dilatation of common hepatic duct (thick yellow arrow), and
gall bladder (thin yellow arrow). (c, d) Axial 3D MRCP and axial T1-weighted MR images depicting course and drainage of cystic
duct (red arrow) unusually distally and continuing as CBD which shows a T2 hypointense
(c), T1 hyperintense (d) calculus (white arrow) within it respectively. 2D, two dimensional; 3D, three dimensional;
CBD, common bile duct; MRCP, Magnetic resonance cholangiopancreatography; MRI, magnetic
resonance imaging.
Fig. 3 (a) 2D MRCP showing blind ending dilated common hepatic duct. Line diagram (b) depicting the final preoperative diagnosis of infantile choledochal cyst associated
with atresia of common hepatic duct distally resulting in dilated common hepatic duct
proximally (thick yellow arrow), normal size of GB (thin yellow arrow), cystic duct
insertion in lower part (red arrow) and a calculus in lower CBD (blue arrow), as correlated
with Coronal T2-weighted MRI image. CBD, common bile duct; GB, gall bladder; MRI,
magnetic resonance imaging.
HIDA (hepatobiliary iminodiacetic acid scan) scan revealed no radioisotope excretion
into gut even after 24 hours. Presumptive diagnosis of choledochal cyst was made before
taking up the patient for laparotomy.
Intraoperatively, hepatomegaly normal size GB, and a 3 × 2.5 cm cyst in subhepatic
region were found ([Fig. 4]). Bile was seen on needle aspiration from cyst. Mobilization of GB was done and
cystic duct was found to be opening into duodenum, without any communication with
the cyst or CHD. The cyst was mobilized and looped with a feeding tube. On further
dissection, cyst was found to have a blind ending distally ([Fig. 5]). Right and left hepatic ducts were patent and opening into the cyst. Both hepatic
ducts were irrigated with saline. Excision of cyst and hepaticodocho-jejunostomy was
done. Distally, ligation and division of cystic duct at the entry into duodenum, and
cholecystectomy completed the procedure. Postoperatively oral feeds were started after
48 hours. Patient passed normal colored stool and showed normal weight gain. Jaundice
had subsided and he was discharged after 5 days.
Fig. 4 Intraoperative image showing normal sized gall bladder, dilated common hepatic duct
(cyst) and cystic duct noncommunicating with common hepatic duct.
Fig. 5 Intraoperative image showing blind ending dilated common hepatic duct (cyst) noncommunicating
with cystic duct.
Histopathological examination of cyst (cuboidal epithelium, stromal mononuclear infiltrates)
and liver (normal lobular architecture and no evidence of fibrosis, giant cells) were
consistent with choledochal cyst.
Follow-up at 6 weeks was done. The patient was healthy, anicteric, taking feeds well,
passing normal colored stool, and gained weight.
Discussion
Todani modification of Alonso-Lej classification classifies CC into five types ([Table 1]).[3] CC in infants needs to be differentiated from cystic biliary atresia due to their
similar clinical presentation.[2] Nondilatation of intrahepatic biliary radicles and absence of biliary epithelial
lining of cyst; differentiates cystic biliary atresia from CC in infants.[1]
[2] Contrary to CC, cystic biliary atresia does not have any continuity with biliary
tree and aspirate of cyst is nonbilious. HIDA scan in cystic biliary atresia does
not reveal any excretion of radioisotope into the gut. Our case had radiological,
intraoperative and histopathological findings of CC but the unusual intraoperative
finding was the completely atretic distal end of CC and noncommunication of cystic
duct with the cyst. This finding does not fit into any of the present classification
of CC.[3]
[4] Though distal stenosis of CC and association of CC with biliary atresia are well
described in literature, an atretic variant of CC is not yet described, to the best
of our knowledge.
Table 1
Todani modification of Alonso-Lej classification for choledochal cyst
|
Type I
|
Fusiform or cystic dilatation of CBD
|
|
Type II
|
Bile duct diverticulum
|
|
Type III
|
Choledochocele
|
|
Type IV
|
Multiple extrahepatic and intrahepatic dilation of duct
IV a both intra and extrhepatic ducts are affected
IV b involves only extraheptic bile duct
|
|
Type V
|
Fusiform or saccular dilation of intrahepatic bile ducts (Caroli disease)
|
This new entity also raises curiosity to its embryological basis. Various hypotheses
have been proposed to explain the development of CC. Most often cited theory is anomalous
pancreaticobiliary junction with reflux of pancreatic juice into the bile duct causing
weakness and dilatation of duct wall.[5] Other theories include distal stenosis, sphincter of oddi dysfunction, faulty remodeling
of the embryonic ductal plate, motility disorders and viral damage to the ganglion
cells of bile duct.[4]
[5]
[6] Our case was not associated with other congenital anomalies so the inciting insult
was probably late perinatal event instead of early embryological one which is usually
associated with congenital anomalies of other organs developing at the same time.[7] The finding of distal atresia of the bile duct with discontinuity of cystic duct
from bile duct is similar to the type-3 jejunoileal atresia (JIA). It is widely accepted
that jejunoileal atresia results from vascular insult late in foetal life. Similar
to JIA, late perinatal ischemic insult can best explain the pathogenesis of this atretic
variant of CC.[8]
[9]
Conclusion
Atretic variant of CC is a newly described entity that can mimic cystic biliary atresia
and other variants of CC in clinical presentation. It requires early surgical intervention
to prevent irreversible changes in the liver. In addition, this variant is expected
to behave like other variants of CC with excellent prognosis if timely intervention
is done.
