Gallbladder Polyp Characteristics and Management
Introduction to Gallbladder Polyps
- Gallbladder polyps can be broadly categorized into two main types: nonneoplastic polyps and neoplastic polyps, with the majority being benign nonneoplastic lesions 1
Nonneoplastic Polyp Characteristics
- Cholesterol polyps account for approximately 60% of all gallbladder polyps, typically small (<10mm) with negligible risk of malignant transformation 1
Neoplastic Polyp Characteristics
- Intracholecystic papillary neoplasms (ICPNs) are mass-forming, noninvasive epithelial neoplasms ≥10mm that project into the gallbladder lumen 1
- ICPNs have four morphologic patterns: biliary, gastric, intestinal, and oncocytic 1
- ICPNs may have low-grade or high-grade epithelial dysplasia 1
- Pyloric gland adenomas are smooth-surfaced polypoid lesions composed of tightly packed glands with pyloric-type low cuboidal epithelium 2
- Pyloric gland adenomas occur in 0.2%-0.5% of cholecystectomy specimens 2
- Pyloric gland adenomas may be associated with familial adenomatous polyposis or Peutz-Jeghers syndrome 2
Morphologic Classification and Risk
- Gallbladder polyps can be classified into three risk categories based on their appearance: extremely low risk, low risk, and indeterminate risk 1, 3
- Extremely low risk polyps are pedunculated with a "ball-on-the-wall" configuration or thin stalk 1, 4
- Low risk polyps are pedunculated with a thick or wide stalk or sessile configuration 1, 4
- Indeterminate risk polyps have focal wall thickening adjacent to the polyp 1, 4
Epidemiology and Clinical Significance
- Only about 6% of all gallbladder polyps are neoplastic 1
- Neoplastic polyps are typically larger (mean size 18-21mm) than nonneoplastic polyps (mean size 4-7.5mm) 2
Diagnostic Features
- On ultrasound, cholesterol polyps typically appear as small, non-mobile, non-shadowing lesions attached to the gallbladder wall 5
- Cholesterol polyps may show stalk-like central enhancement on contrast-enhanced ultrasound (CEUS) 5, 4
- MRI may show high T1-weighted signal in cholesterol polyps 5
Risk Factors for Malignancy
- Size ≥10mm is the strongest predictor of malignancy 4
- Sessile morphology increases risk of malignancy 4
- Rapid growth (≥4mm within 12 months) is concerning for malignancy 4
- Focal wall thickening adjacent to polyp suggests higher risk 4