Diagnostic ultrasound ( PDFDrive )

CHAPTER 6 The Biliary Tree and Gallbladder 185
A
B
C
FIG. 6.24 Immunoglobulin G Subtype 4 (IgG-4)–
Related Cholangitis. (A) Transverse image through the
common hepatic duct at the porta hepatis demonstrates
marked circumferential wall thickening (short arrows), much
more so than usual for primary sclerosing cholangitis.
(B) Transverse view slightly cranial to (A) shows obliteration
of the central ductals due to marked periductal hypoechoic
inlammatory/ibrotic disease (short arrows). Note the dilated
ducts upstream. (C) Longitudinal view of the gallbladder
shows similar concentric wall thickening (short arrows)
without distention.
echotexture, and it may appear hypoechoic, isoechoic, or
hyperechoic (Fig. 6.25). A clue to the diferentiation from
hepatocellular carcinoma is a much higher incidence of ductal
obstruction, reportedly occurring in 31% of patients with
intrahepatic cholangiocarcinoma and only 2% of those with
hepatocellular carcinoma. 60,61 Contrast-enhanced ultrasound
also provides diferentiating features (see Chapter 4 for further
discussion). However, a solitary metastasis to the liver may cause
intrahepatic ductal obstruction and therefore may be diicult to
distinguish. 62
A more unusual manifestation of intrahepatic cholangiocarcinoma
is a purely intraductal mass, called intraductal intrahepatic
cholangiocarcinoma. hese polypoid masses distend
the afected ducts, oten third-order or fourth-order branches,
spreading within the duct and illing it with mucin. hese tumors
have a much better prognosis and are thought to be histologically
separate from other intrahepatic cholangiocarcinomas, resembling
papillary tumors of the extrahepatic bile ducts. 59,63 he most
common appearance of the intraductal intrahepatic cholangiocarcinoma
is one or more polypoid masses conined to the bile
ducts. Abundant mucin production, manifest sonographically
with a subtle layered appearance, can greatly distend the afected
lobar and distal ducts (Fig. 6.26). Occasionally a focal mass is
not evident as the disease difusely afects the bile ducts, as a
result of biliary papillomatosis, a rare condition in which there
is difuse papillary adenoma formation throughout the biliary
tree. 64 A less common form may present as a solid mass within
a cystic structure, representing tumor within an extremely
distended duct that does not communicate with the biliary tree
(Fig. 6.27).
Hilar Cholangiocarcinoma
he correct identiication and staging of hilar cholangiocarcinoma
are challenging with all imaging modalities because of the
tumor’s desmoplastic nature (causing ibrous tissue formation),
its peribiliary and subendothelial patterns of growth, and the