Gallbladder Carcinoma

Todd M. Blodgett, MD

Alex Ryan, MD

Hesham Amr, MD

Key Facts

Imaging Findings

GB mass with intense uptake often invading into liver
FDG PET for evaluation of localized or metastatic GBC
Also for staging and restaging malignant tumors leading to detection of unsuspected mets in 25-30% and leading to major changes in therapy in 15-20% of cases
CECT can demonstrate tumor extension outside GB and identify metastatic disease in the abdomen and pelvis
Intense FDG uptake in the primary GB mass often directly extends into liver
Abnormal uptake along bile ducts with subserosal and regional lymph node invasion
PET often reveals disease in nonenlarged lymph nodes
Distant hematogenous metastasis and peritoneal seeding may occur

Top Differential Diagnoses

Cholecystitis
Cholangiocarcinoma
Metastases
Gallbladder Polyp
- Benign polyps in 4-6% of the general population; most show no radiotracer uptake

Diagnostic Checklist

Pitfall: Misregistered normal bowel activity onto liver or GB can be misleading without CT correlation for presence of mass lesions

Graphic shows typical appearance for gallbladder carcinoma

with hepatic invasion

Specimen shows a tannish red mass in the gallbladder

with extension outside the walls of the gallbladder

, compatible with carcinoma of the gallbladder.

TERMINOLOGY

Abbreviations and Synonyms

Gallbladder (GB), gallbladder cancer (GBC)

Definitions

Malignant neoplasm arising from epithelial layer of the gallbladder mucosa

IMAGING FINDINGS

General Features

Best diagnostic clue: FDG-avid mass of the gallbladder with invasion of liver
Location
- Most common site of recurrence is laparoscopic port incision
- Most frequent sites of lymph node invasion are pericholedocal and cystic
Size
- Variable, but usually large at diagnosis
- Can be polypoid lesion if detected incidentally on CT
Morphology
- Early disease presents as diffuse wall thickening or polyp
  - Rarely seen, as disease frequently presents in advanced stages
- Advanced disease usually appears as large mass with signs of infiltration

Imaging Recommendations

Best imaging tool
- Ultrasound
  - Mass within the gallbladder or focal thickening of the gallbladder wall
- Endoscopic retrograde cholangiopancreatography (ERCP)
  - Obtain tissue sample for histologic diagnosis
  - Localize obstruction in jaundiced patients
  - Stent placement in the case of obstruction
- CT/MR
  - Delineation of local invasion and metastatic disease, particularly in relation to vascular structures
- FDG PET
  - Initial diagnosis when clinically indicated (rare)
  - Staging and restaging (25-30% rate of detection of unsuspected metastatic disease, 15-20% rate of major change in therapeutic planning)
Protocol advice
- Use contrast-enhanced CT when possible for patients with suspected or known GB malignancy
- FDG PET protocol
  - ≥ 6 hour fast prior to scan
  - Patient with serum glucose ≥ 200 mg/dl should be rescheduled
  - Avoid exercise or cold temperatures prior to scan
  - Administer 370-555 MB (10-15 mCi) F-18 FDG IV 1-2 hours before scan
  - Scan with arms above head
  - Post-operative patients should be given 4-6 weeks to resolve inflammation prior to scan

CT Findings

Mass and thickening
- Mass form is more common due to late diagnosis of most cases
  - Heterogeneous
  - Hyperdense areas due to necrosis
  - Hypovascular, poorly enhancing mass infiltrating GB fossa
  - Often direct extension to liver along main lobar fissure
  - Common duct invasion and periportal adenopathy present as hazy density around duct
- Early disease presents as wall thickening
  - Focal and irregular
  - Disease may originate at site of chronic cholecystitis
  - Sometimes indistinguishable from inflammatory conditions
  - Evidence for neoplasm includes hyperemia of thick inner layer that is iso- or hyperattenuating to liver in portal phase
Gallstones
- Association with porcelain gallbladder unclear, but its presence is frequently reported
- Calcific gallstones present in 65-75% of patients with GBC
  - Less than 1% of patients with gallstones develop GBC
Staging
- CT limited in staging the following entities
  - Nonenlarged malignant lymph nodes
  - Distant lymph nodes
  - Small liver metastases
  - Peritoneal seeding
  - Early vs. benign lesions
- Invasion of liver and porta hepatis common
- Whole body scanning important for detection of distant lung and bone metastases
- Intraperitoneal metastasis and carcinomatosis indicate advanced disease
Lymph nodes
- CECT may reveal lymphadenopathy in the porta hepatis
- Involved lymph nodes appear ring-shaped with heterogeneous contrast enhancement
- Metastasis to peripancreatic lymph nodes easily confused for pancreatic carcinoma

Nuclear Medicine Findings

FDG PET and PET/CT
- Initial diagnosis
  - FDG PET has limited role in initial diagnosis because most GBC is diagnosed incidentally within the gallbladder after cholecystectomy
  - Tumor masses show peripheral uptake with areas of low uptake when there is necrosis
  - Uptake in primary mass may be seen to extend into liver in the presence of hepatic invasion
  - Mucinous tumors often demonstrate low FDG avidity
- Staging
  - According to one study, typical SUV of metastatic disease ranges from 2.7-7.5
  - FDG PET often detects distant disease unsuspected on CT alone, particularly in nonenlarged lymph nodes
  - Major weakness of FDG PET alone is poor sensitivity for carcinomatosis
  - Metastasis tends to show increased radiotracer uptake
  - Combined-modality PET/CT superior to CECT for detection of metastasis
  - Low sensitivity for regional lymph node detection (vs. 24-40% sensitivity with CECT)
  - Regional and subserosal lymph node invasion may appear as abnormal uptake along bile ducts
- Restaging
  - Most important contribution of FDG PET and PET/CT is identification of recurrent and metastatic disease
  - Interpretation of residual tumor in gallbladder fossa following cholecystectomy can be obscured by post-surgical inflammation
  - Sensitivity and specificity for recurrent disease approximately 80% and 80%
- Response to therapy
  - FDG PET has been used for determination of therapy response, although there is a paucity of studies in the current literature