What are the characteristic findings of Xanthogranulomatous Cholecystitis (XGC) on Computed Tomography (CT) imaging?

Characteristic CT Findings of Xanthogranulomatous Cholecystitis (XGC)

The most distinctive CT findings of Xanthogranulomatous Cholecystitis (XGC) include diffuse gallbladder wall thickening, intramural hypoattenuated nodules occupying >60% of the thickened wall, continuous enhancing mucosal line, and the presence of gallstones. 1, 2, 3, 4

Key CT Imaging Features of XGC

Primary Diagnostic Features

• Gallbladder wall thickening:

  • Average thickness of 1.8 cm 2
  • Predominantly diffuse pattern (87.8-90.9% of cases) 4, 3
  • More diffusely thickened compared to gallbladder cancer 2

• Intramural hypoattenuated nodules:

  • Present in 85.7-100% of XGC cases 4, 2
  • Highly specific when occupying >60% of the thickened wall 3
  • Statistically significant differentiator from gallbladder cancer (p=0.008) 2

• Continuous mucosal line:

  • Visible in 79.6-81.8% of cases 4, 2
  • Intact and enhancing in XGC (90.9%) vs. disrupted in gallbladder cancer 3
  • Statistically significant differentiator (p=0.02) 2

• Luminal surface enhancement:

  • Present in 85.7% of XGC cases 4
  • Helps differentiate from gallbladder cancer

Associated Findings

• Gallstones:

  • Present in 69.4-76.5% of XGC cases 4, 5
  • More common in XGC than gallbladder cancer (p=0.053) 5

• Pericholecystic infiltration/inflammation:

  • Extension beyond gallbladder in 60% of cases 4
  • Blurred interface between gallbladder and liver/surrounding fat
  • Early enhancement of adjacent liver parenchyma in 40% of cases 4

Differentiating from Gallbladder Cancer

Features favoring XGC over gallbladder cancer:

• Diffuse (rather than focal) wall thickening 2
• Intramural hypoattenuated nodules occupying large areas of the wall 2, 3
• Intact, continuous mucosal line 3
• Absence of obstructive biliary features 3
• Absence of intraluminal mass (only 9.1% in XGC vs. 61.1% in cancer) 5
• Absence of lymphadenopathy (0% in XGC vs. 18.8% in cancer) 5

Clinical correlation

• Younger age and male gender more common in XGC 5
• Elevated white blood cell count more typical of XGC (mean 16.4 vs. 8.6 in cancer) 5
• Abdominal pain, fever, and jaundice more frequent in XGC 1

MRI Findings in XGC

• On T1-weighted dual echo MR images, intramural nodules show higher signal intensity on in-phase images than out-of-phase images 4
• Chemical-shift MRI helps classify intramural nodules in the gallbladder wall 4

Diagnostic Pitfalls and Caveats

• Despite characteristic findings, there remains significant overlap with gallbladder cancer 2
• CT sensitivity for gallstone detection is only approximately 75% 6, 7
• Definitive diagnosis may require frozen section during surgery 3
• XGC can present technical challenges during cholecystectomy due to significant adhesions/inflammation (83.8% of cases) 5

When multiple characteristic findings (diffuse wall thickening, intramural hypoattenuated nodules, continuous mucosal line, luminal enhancement, and gallstones) coexist, the diagnosis of XGC can be made with higher confidence, potentially avoiding unnecessary radical surgery 3, 4.