Keywords
biliary atresia - cholangiopathy - common hepatic duct
Introduction
Biliary Atresia (BA) is an inflammatory progressive cholangiopathy that affects the
intrahepatic and extrahepatic biliary tree. It is categorized into three types, of
which type III in which the biliary tree is completely atretic is the most common.[1]
[2] Type II is the rarest where the atresia is at the level of the common hepatic duct.
Here, we describe a 4-month-old infant who presented with cholestatic jaundice. Ultrasound
and MRCP were suggestive of type IIB BA that was confirmed with a percutaneous transhepatic
cholangiogram (PTC) and liver biopsy.
Case History
A 4-month-old female patient presented with complaints of jaundice with acholic stools
and high colored urine since day 5 of life. On general examination, she was alert
and had pallor and icterus. Abdominal examination showed firm hepatomegaly, splenomegaly,
and moderate ascites. Laboratory investigation showed conjugated hyperbilirubinemia—total/direct
bilirubin (14.03/9 mg/dL) and raised gamma-glutamyl transpeptidase (GGT) activity
724 (<40 IU/mL). Serology for CMV (IgM) was negative.
Clinically, a possibility of a biliary obstructive pathology was considered and the
child was evaluated. Ultrasound (LOGIQS8, GE, UK) was performed after withholding
feeds for 3 to 4 hours using a curvilinear (4–5 MHz) and a high-frequency linear transducer
that revealed hepatomegaly (9 cm) with a coarsened echotexture and reduced echogenicity.
There was a surface irregularity with a nodular outline, suggestive of chronic liver
disease (CLD). There was moderate bilobar intrahepatic biliary radical dilatation
(IHBRD) with inspissated secretions within the dilated biliary radicles. Gall bladder
(GB) and common bile duct (CBD) were not visualized on repeated scans 24 hours apart.
A triangular cord sign was evident ([Fig. 1C]); however, a hepatic artery was not prominent. The subcapsular flow was also not
evident. The spleen was enlarged and there was free fluid in the peritoneal cavity
([Fig. 1]). MRI abdomen with MRCP revealed moderate central bilobar IHBRD with an abrupt cutoff
at the level of the common hepatic duct (CHD). Primary confluence was patent. Cystic
duct, CBD, and GB were not visible on MRCP. There was crossed fused ectopia, and the
right kidney was lying on the left side below the left kidney ([Fig. 2]).
Fig. 1 (A–D) Transverse grayscale ultrasound using curvilinear and linear probes show nonvisualization
of the gall bladder with empty GB fossa (arrow in A). There were dilated biliary radicles in both lobes (arrow in B) with coarsened echotexture of the liver. There was increased echogenicity seen anterior
to the portal vein, and CBD was not visualized at porta, which was suggestive of a
triangular cord sign (arrow in C). Free fluid was also seen in the peritoneal cavity (arrow in D). CBD, common bile duct; GB, gall bladder.
Fig. 2 (A–D) T2W FS coronal image showing bilobar intrahepatic biliary radicles dilatation (arrow
in A) with patent primary confluence and abrupt cutoff at the level of the common hepatic
duct (arrow in B). Cystic duct, common bile duct, and gall bladder are not visualized. T2 hypointense
inspissated secretions/plugs are seen in the dilated biliary radicles (arrow in C). Crossed fused renal ectopia is also seen. The right kidney is seen on the left
side at the inferior aspect of the left kidney which is also malrotated (arrow in
D). T2W FS, T2-weighted fat saturated.
As the child had features of decompensated liver disease, a surgical drainage procedure
was not deemed feasible, and percutaneous transhepatic biliary drainage was done as
a temporary measure to relieve jaundice through the right biliary system. Percutaneous
transhepatic cholangiogram (PTC) revealed bilobar IHBRD with an abrupt cutoff at the
CHD. Primary confluence was patent; however, there was no passage of contrast into
distal CHD/CBD ([Fig. 3]). As the stricture was not negotiable, the child was put on external drainage. In
view of PTC findings, hepatobiliary iminodiacetic acid (HIDA) scan was not performed
and a radiological diagnosis of BA type IIB was made. Subsequently, an ultrasound-guided
liver biopsy was done. The portal tracts showed fibrous portal tract expansion and
bile duct proliferation. There was the presence of intrahepatic and intracanalicular
biliary cholestasis and portal to central fibrosis with nodule formation ([Fig. 4]). Features were suggestive of cirrhosis secondary to BA. Upper gastrointestinal
endoscopy showed small esophageal varices and the major duodenal papilla was not visualized
in the duodenum.
Fig. 3 (A) Percutaneous cholangiogram using the right ductal approach showing patent primary
confluence with dilated bilobar ducts and abrupt cutoff at the CHD level (*). No passage
of contrast seen in distal CHD, CBD, or duodenum. (B) An external drainage catheter was inserted for decompression and drainage of the
biliary system (arrow). CBD, common bile duct; CHD, common hepatic duct.
Fig. 4 (A) Microphotograph showing hepatocytes with ballooning. Degeneration (triangle). Intracanalicular
(star) and intrahepatic (arrow) cholestasis is also noted. (HE x400). (B) Microphotograph showing bile duct proliferation (star). (HE x400). (C) Magnified view showing nodule formation (arrows), with surrounding fibrosis (Masson's
trichrome ×100). HE, hematoxylin and eosin.
A liver transplant was planned. Unfortunately, while undergoing evaluation, the child
developed spontaneous bacterial peritonitis and died of severe sepsis.
Discussion
BA is a rare congenital cause of biliary obstruction. The etiology is still elusive
although several viral, genetic, and immune-mediated theories have been postulated.[2] There is inflammatory damage to both intrahepatic and extrahepatic bile duct leading
to sclerosis, narrowing, and complete obliteration of the biliary tree, which leads
to progressive fibrosis of the liver and eventually cirrhosis as seen in our child.
The clinical presentation consists of jaundice, acholic stools, and dark urine, and
hepatomegaly. They generally appear well initially and have normal growth despite
their jaundice, which leads to a delayed referral as seen in our child. Laboratory
analysis includes direct hyperbilirubinemia and elevated GGT.[3]
Two forms of BA, syndromic or biliary atresia splenic malformation (∼10%), associated
with other congenital anomalies and non-syndromic (∼90%) in which BA is the isolated
anomaly are described.[2] Our child had associated crossed fused ectopia of the kidneys along with BA.
The Japanese Association of Pediatric Surgeons is the most widely used classification
of BA, which is based on the level of atresia and is as follows.[4]
-
Type I: Atresia at the level of CBD (12%), also known as distal BA. Gall Bladder and
hepatic ducts are patent. Type II: Atresia at the level of CHD (2.5%)-Rarest form.
Type 2 is divided into IIA and IIB. CBD, cystic duct, and GB are patent in Type IIA,
while obliterated in Type IIB.
-
Type III: Atresia at the porta hepatis (85%), also known as complete BA.
Diagrammatic Representation of Classification of EHBA
Diagrammatic Representation of Classification of EHBA
The described infant was Type IIB BA, which is the rarest. The most commonly encountered
BA is complete or Type III BA in which there is non-visualization of bile ducts and
cystic duct and gall bladder. In other subtypes, bile ducts and gall bladder can be
seen depending on the level of atresia. Due to limited literature available on other
subtypes, the status of biliary radicles proximal to the atresia in other types is
not described previously. In our patient, intrahepatic biliary radicles were dilated,
so other differentials such as congenital stricture or web and inspissated bile duct
syndrome were also considered.
Ultrasound is the preliminary investigation and requires fasting for at least 6 hours.
Depending on the type, numerous sonographic findings are seen that include either
nonvisualization or rudimentary GB, absence of contraction after feeding, and presence
of triangular cord sign in the vicinity of the portal vein in type III BA[5] GB is visualized in type I and IIA. Ultrasound will also detect the changes of CLD
and portal hypertension as is seen in our case. Color Doppler findings include dilated
hepatic artery and increased subcapsular flow that aid in the diagnosis.[6] Our case showed IHBRD with nonvisualization of CBD and GB and superimposed CLD,
suggesting type IIB BA.
MRI of the abdomen with MRCP is done to confirm the findings, for better depiction
of biliary anatomy, level of atresia, as well as to look for any other associated
congenital anomaly. The sensitivity of MRCP is 90 to 100% and specificity is 77 to
96%.[7] Nonvisualization of the extrahepatic biliary tree and GB is the diagnostic hallmark
of BA; however, the demonstration of only a normal CBD also does not necessarily exclude
BA, as the disease may involve only the proximal extrahepatic biliary system. In our
patient CBD, cystic duct and gall bladder were not visualized, and there were dilated
biliary radicles with T2 hypointense-filling defects, suggestive of inspissated secretions.
These imaging features were consistent with a diagnosis of type IIB BA, which was
confirmed by the percutaneous transhepatic cholangiogram (PTC) that demonstrated moderate
dilatation of bilobar biliary radicles with a patent primary confluence. Just distal
to the formation of CHD, there was an abrupt cutoff with non-passage of contrast distal
to it. In children, inspissated bile duct syndrome may often mimic BA, and PTC cannot
only help in establishing the diagnosis by showing ductal filling defects but an attempt
at therapeutic lavage also can be made.[8] A congenital stricture or web of the common hepatic duct is another rare condition
that may present with features of biliary obstruction; however, the early clinical
presentation and aggressive clinical course with features of established cirrhosis
by 4 months of age would make it unlikely. An absent GB with non-visualization of
the web, which is seen as a linear-filling defect on MRCP ruled out the diagnosis
of the congenital web on imaging.[9] The diagnosis of BA was further corroborated by the liver biopsy findings, which
had a diagnostic accuracy of 90.1% for BA.[10] A Kasai portoenterostomy is the treatment of choice; however, in children who present
late with features of advanced cirrhosis, as seen in our child, one has to proceed
directly for liver transplantation. We planned for the same but unfortunately, the
child died of sepsis while undergoing evaluation for the same ([Fig. 5]).
Fig. 5 Diagrammatic representation of the classification of biliary atresia.
To conclude, we describe the multimodality imaging features of a child with Type IIB
BA which is the rare type. Various imaging findings of Type III EHBA, which is the
commonest type, are described previously; however, the imaging findings of type IIB
have not been described previously to the best of our knowledge.
