– Mass completely replacing gallbladder (GB) (2/3 of cases)
– Irregular focal or diffuse GB wall thickening (20-30%)
– Intraluminal polyploid GB mass (∼ 20% of cases)
Typically hypodense on venous phase, but may have peripheral vascularity on arterial phase
Frequently invades liver and porta hepatis
Bulky porta hepatis/paraaortic adenopathy common
Most common sites of metastasis: Liver and peritoneum
Calcified gallstones or porcelain GB may be present
• US findings
Asymmetric GB wall thickening or a discrete polyploid, heterogeneous, moderately echogenic GB mass
Hepatic invasion with loss of normal echogenic GB wall dividing mass from liver
Internal color flow vascularity on color Doppler
TOP DIFFERENTIAL DIAGNOSES
• Complicated or chronic cholecystitis
• Xanthogranulomatous cholecystitis
• Metastatic disease to gallbladder
• Gallbladder polyp or adenomyomatosis
PATHOLOGY
• Major risk factors: Cholelithiasis, chronic cholecystitis, porcelain GB, and GB polyps
CLINICAL ISSUES
• Most common in elderly female patients
• Many patients are asymptomatic, with incidental diagnosis after cholecystectomy for gallstones or cholecystitis
• Very poor prognosis: 5-year survival rate of 4%
75% of patients have metastases at time of diagnosis
• T stage determines surgical approach (simple or extended cholecystectomy ± radical resection (liver, colon, etc.)
(Left) Schematic drawing of gallbladder (GB) carcinoma shows gallstones and a focal mural mass arising from the GB wall, invading the adjacent liver and obstructing the common hepatic duct.
(Right) Coronal CECT demonstrates a soft tissue mass arising from the GB and extending superiorly to invade the liver and porta hepatis. Note the presence of multiple gallstones , a known major risk factor for GB carcinoma.
(Left) Axial CECT demonstrates a large, enhancing polyploid mass in the GB, in keeping with GB carcinoma. Such polyploid masses only account for roughly 20% of all GB cancers detected on CT.
(Right) Ultrasound demonstrates a soft tissue mass filling the GB fundus, in keeping with a GB carcinoma. Note that the echogenic GB wall is intact between the mass and liver, suggesting that there is no liver invasion.
TERMINOLOGY
Definitions
• Malignant epithelial neoplasm arising from gallbladder (GB) mucosa
IMAGING
General Features
• Best diagnostic clue
Large GB mass completely replacing the gallbladder and extending into liver
Polypoid mass within GB lumen
Diffuse or focal irregular gallbladder wall thickening
• Location
GB fundus and body, uncommon in cystic duct
• Size
Variable: Smaller polypoid mass in early stage, large infiltrating lesions are more typical in later stages
• Morphology
Large soft-tissue mass infiltrating GB fossa; polypoid mucosal mass in GB
Radiographic Findings
• Radiography
Plain abdominal radiographs
– Calcified gallstones or porcelain GB
Oral cholecystogram (OCG)
– Nonvisualization of GB
– Rarely pneumobilia secondary to GB enteric fistula
• ERCP
Limited utility since GB is usually nonvisualized
May demonstrate common hepatic duct obstruction with dilated intrahepatic ducts
CT Findings
• Accuracy of CT for GB cancer between 84-92%
• Intraluminal polyploid GB mass (∼ 20% of cases), irregular focal or diffuse GB wall thickening (20-30% of cases), or mass completely replacing GB (2/3 of cases)
May be difficult to differentiate from primary liver mass when large mass replaces GB and invades liver
May be difficult to differentiate from Klatskin tumor (cholangiocarcinoma) when tumor invades porta hepatis
GB cancer presenting as wall thickening (especially when diffuse) difficult to differentiate from chronic cholecystitis; look for irregular wall thickening, metastases, and locoregional enlarged lymph nodes
Typically a hypodense mass on portal venous phase, but may have peripheral vascularity on arterial phase
– 2-layer pattern of enhancement in thickened GB wall (hypoenhancing outer layer and hyperemic inner layer)
– May have calcifications (possibly engulfed gallstones) and cystic components (usually mucinous tumors)
• Frequent invasion of liver and porta hepatis
• Bulky porta hepatis and paraaortic lymphadenopathy common
• Most common sites of metastasis: Liver (either via direct invasion or hematogenous metastases) and peritoneum (usually in RUQ omentum)
• Calcified gallstones or porcelain GB may be present
• Adenosquamous and squamous cell carcinomas of GB tend to be larger at presentation with greater tendency for invasion of adjacent structures (especially liver)
Possible lesser risk of distant or lymph node metastases
Usually unresectable due to local aggressiveness
MR Findings
• MR findings parallel CT in terms of tumor morphology
• GB carcinoma usually T1 hypointense, T2 intermediate to hyperintense, and hypoenhancing on T1WI C+ images
• MR may provide some value for T-staging and may be slightly more sensitive than CT for early liver invasion
• Malignant GB lesions often show restricted diffusion
Ultrasonographic Findings
• Asymmetric GB wall thickening or a discrete polyploid, heterogeneous, moderately echogenic GB mass
Mass may completely replace the GB making it difficult to establish site of origin
Frequent hepatic invasion with loss of normal echogenic GB wall dividing mass from liver
• Should be immobile when patient positioning is altered
• Associated with gallstones and porcelain GB
• Usually associated with internal color flow vascularity on color Doppler ultrasound
Lack of vascularity cannot exclude malignancy when confronted with suspicious wall thickening or mass
Nuclear Medicine Findings
• Hepatobiliary scan: Nonfilling of GB can mimic cholecystitis
• PET/CT: Most GB cancers are FDG avid, although role for PET/CT in preoperative evaluation is unclear
May identify occult metastases and change management in ∼ 20%
Imaging Recommendations
• Best imaging tool
US, CECT, MR
• Protocol advice
Longitudinal and transverse images of GB fossa with both grayscale and color Doppler
arising from the GB and extending superiorly to invade the liver and porta hepatis. Note the presence of multiple gallstones 
, a known major risk factor for GB carcinoma.
in the GB, in keeping with GB carcinoma. Such polyploid masses only account for roughly 20% of all GB cancers detected on CT.
filling the GB fundus, in keeping with a GB carcinoma. Note that the echogenic GB wall 
is intact between the mass and liver, suggesting that there is no liver invasion.
May be difficult to differentiate from primary liver mass when large mass replaces GB and invades liver
May be difficult to differentiate from Klatskin tumor (cholangiocarcinoma) when tumor invades porta hepatis
GB cancer presenting as wall thickening (especially when diffuse) difficult to differentiate from chronic cholecystitis; look for irregular wall thickening, metastases, and locoregional enlarged lymph nodes
