Carcinoma of the gallbladder is not uncommon,
it accounts for up to 3 pet cent of primary malignancies. Carcinoma
of the gallbladder is the most common cancer of the biliary tract,
and most tumors occur in the gallbladder fundus. Most gallbladder
cancers are classified as adenocarcinoma.
The etiology is unclear; however, risk factors include gallstones
: the vast majority of gallbladder cancers are associated with
gallstones : It probably occurs because of chronic irritation
of the gallbladder wall by stones. Other particular risk factors
for gallbladder carcinoma include : porcelain gallbladder, polyps
of over 1 cm in size, chronic cholecystitis, exposure to carcinogens,
and occasionally, choledochal cyst due to anomalous junction of
the pancreato-biliary ducts. Gallbladder carcinoma is also more
common in female patients and in older persons.
The clinical symptoms are nonspecific in the early stages and
may mimic benign gallbladder disease. Patients may have weight
loss, anorexia, right upper quadrant pain, jaundice, nausea and
vomiting, and hepatomegaly. Late diagnosis is more common, which
speaks to the poor prognosis of this malignant disease for which
the mean survival rate is 6 months.
The most common sonographic appearance for gallbladder cancer
is a soft tissue mass centered in the gallbladder fossa that completely
or partially obliterates the lumen.
Tumor has usually invaded the gallbladder bed before the onset
of symptoms. Local infiltration usually inters a poor prognosis.
The carcinoma may be infiltrating causing diffuse thickening and
induration of the gallbladder wall or fungating resulting in a
mass which fills the gallbladder lumen and invades the wall. Gallbladder
polyps over 2 cm in size have a 65 to 95 % chance of being malignant.
Identification of gallstones within the mass can help to confirm
that the origin of the mass is the gallbladder rather than adjacent
Sonographically, gallbladder carcinoma may
have different appearances:
* 1. gallstones within a mass
strongly suggest carcinoma of the gallbladder
* 2. Localized or diffuse
thickening of the gallbladder wall.
* 3. Intra-luminal polypoid
or fungating mass.
* 4. diffusely echogenic masse
* 5. extensive tumor spread
causing obstructive jaundice
* 6. low echogenicity mass
extending into the porta and liver
* 7. high velocity arterial
flow signal in tumor mass on color flow Doppler.
* 8. Color Doppler imaging
may be used to differentiate biliary sludge, which is avascular,
from a hypoechoic mass, which would show flow.
* 9. colour flow signal in
the gallbladder wall
* 10. The vast majority of
patients with gallbladder carcinoma will demonstrate cholelithiasis.
Other findings such as dilated bile ducts, regional adenopathy,
or hepatic metastases may be seen. There is an increased incidence
of gallbladder carcinoma in patients with gallbladder wall calcification
(porcelain gallbladder), though most gallbladder carcinomas will
not demonstrate this finding.
* 11. spread from carcinoma
of the gallbladder may cause lymphadenopathy in the region of
the head of the pancreas, this may obstruct the common bile duct
and mimic carcinoma of the head of the pancreas.
The differential diagnosis for gallbladder
masses includes tumefactive sludge (biliary sludge, which is avascular),
inflammatory wall thickening, polyps, metastases, and focal adenomyomatosis.
Nonmalignant causes of gallbladder wall thickening, such as cholecystitis
and hyperplastic cholecystosis, can simulate gallbladder carcinoma.
Malignant entities which may cause confusion include pancreatic
carcinoma and metastasis to the gallbladder (the most common being
Primary gallbladder carcinoma is an uncommon but highly malignant
neoplasm which quickly metastasizes to the liver and portal nodes
and has a very poor prognosis. The 5-year survival rate for patients
is less than 20%, although the prognosis for patients with tumor
confined to the gallbladder wall is much better. Unfortunately,
up to 80% of these patients have direct tumor invasion of the
liver or portal node involvement at the time of diagnosis.