Diagnostic ultrasound ( PDFDrive )

184 PART II Abdominal and Pelvic Sonography
A
B
FIG. 6.23 Cholangiocarcinoma in Primary Sclerosing Cholangitis. (A) An iniltrative mass is seen centered on dilated ducts. (B) Contrastenhanced
ultrasound in the venous phase improves the visualization of the tumor margins and extent, including a satellite subcapsular focus not
visible on the gray-scale scan. See also Videos 6.7 and 6.8.
more pronounced than in primary sclerosing cholangitis (single
wall thickness > 3 mm) and can appear masslike (Fig. 6.24). 47
Strictures are longer and continuous as opposed to skip disease
in primary sclerosing cholangitis, but mucosal irregularity, which
is an important feature of primary sclerosing cholangitis, is diicult
to appreciate. Many patients with IgG4-related cholangitis have
involvement of other organs, which can be searched for during
the scan; pancreatic involvement virtually makes the diagnosis.
Many of the changes improve within weeks of commencement
of steroid therapy.
Cholangiocarcinoma
Cholangiocarcinoma is an uncommon neoplasm that may arise
from any portion of the biliary tree. Its incidence varies geographically
and is highest in populations with known risk factors. Overall
incidence ranges from 1 or 2 per 100,000 population in the
United States, 2 to 6 in other Western countries, 5.5 in Japan,
and up to 130 per 100,000 in northeastern hailand, where the
liver luke Opisthorchis viverrini is endemic. 48,49 he frequency
of cholangiocarcinoma increases with age, with the peak incidence
in the eighth decade. Most cholangiocarcinomas are sporadic,
but several risk factors exist, usually related to chronic biliary
stasis and inlammation. Primary sclerosing cholangitis is the
most common risk factor for cholangiocarcinoma in the Western
world; the lifetime risk of developing a clinically detectable
cholangiocarcinoma in these patients is about 10%. 50 he most
common risk factors in other populations are recurrent biliary
infections and stone disease.
Cholangiocarcinomas are classiied based on the anatomic
location: intrahepatic, also called peripheral (≈10%); hilar, also
called Klatskin (≈60%); and distal (≈30%). 51 Approximately 90%
of cholangiocarcinomas are adenocarcinomas, with squamous
carcinomas the next most common subtype. 52 Macroscopically,
cholangiocarcinomas are divided into three subtypes: sclerosing,
nodular, and papillary; the irst two subtypes frequently occur
together. Nodular-sclerosing tumors, the most common subtype,
appear as a irm mass surrounding and narrowing the afected
duct, with a nodular intraductal component. Most hilar cholangiocarcinomas
are of the nodular-sclerosing variety. hese
tumors incite a prominent desmoplastic reaction and demonstrate
a periductal, perineural, and lymphatic pattern of spread along
the ducts, as well as subendothelial spread within the ducts.
Papillary cholangiocarcinomas represent approximately 10%
of these tumors and are most common in the distal CBD. Patients
present with an intraductal polypoid mass that expands, rather
than constricts, the duct. 51,53,54
he overall prognosis for cholangiocarcinoma is poor. In a
large, single-center series, the 5-year survival rate for patients
with intrahepatic, hilar, and distal cholangiocarcinoma was 23%,
6%, and 24%, respectively, and improved to only 44%, 11%, and
28% in patients who underwent resection. 55
Intrahepatic Cholangiocarcinoma
Intrahepatic cholangiocarcinoma, also called peripheral
cholangiocarcinoma, are the least common location for cholangiocarcinomas,
but they represent the second most common
primary malignancy of the liver. hey arise from the second-order
or higher-order branches of the biliary tree within the liver
parenchyma, and their histologic origin is diferent than that
of extrahepatic ducts. he incidence of intrahepatic cholangiocarcinomas
has been increasing in part because of the increase in
numbers of patients with liver cirrhosis and long-term hepatitis
C infection. 56 Hepatitis B also has recently been identiied as a
risk factor. 57 hese tumors are associated with a poor prognosis
because the mass is oten unresectable. 58,59
he most common manifestation of intrahepatic cholangiocarcinoma
is a large hepatic mass. he sonographic appearance
is oten that of a hypovascular solid mass with heterogeneous