Gallbladder Polyps

 Large polyps may show internal color flow vascularity

image “Comet tail” artifacts suggest cholesterol polyp

• CT: Useful for staging in larger polyps where ↑ risk of malignancy
image Difficult to visualize many polyps on CT due to lower spatial resolution

image Can show variable enhancement; no convincing correlation between enhancement and malignancy

image Useful for staging in larger polyps where ↑ risk of malignancy


• Tumefactive sludge

• Gallstone

• Polypoid GB carcinoma

• GB metastases

• Adenomyomatosis


• Classification
image Neoplastic: Adenoma, adenoma-carcinoma, miscellaneous (fibroma, lipoma, etc.)

image Nonneoplastic: Cholesterol polyp, adenomyoma, inflammatory polyp, choristoma


• Size is most important predictor of malignancy
image 100% of polyps > 20 mm are malignant

image 43-77% of polyps 10-20 mm are malignant

image 94% of benign polyps are < 10 mm

• Risk factors for malignancy: Age > 60, gallstones, coexistence of primary sclerosing cholangitis (PSC)

• Reassuring factors: Stability over time, multiple polyps, pedunculated (versus sessile) morphology

• Current recommendations
image Cholecystectomy if patient is symptomatic or has cholelithiasis or PSC (regardless of polyp size)

image Polyp > 18-20 mm: Open cholecystectomy

image Polyp 10-20 mm: Laparoscopic cholecystectomy

image Polyp 6-9 mm: Serial follow-up at 3, 6, and 12 months

image Polyp ≤ 5 mm: Serial imaging (no consensus; malignancy is extremely rare and some advocate no follow-up)

(Left) Ultrasound of a 43-year-old woman with right upper quadrant pain shows mild gallbladder (GB) wall thickening and multiple small (< 5 mm), slightly echogenic polyps image. An elective laparoscopic cholecystectomy for presumed biliary colic revealed cholesterolosis and cholesterol polyps.

(Right) Ultrasound image shows multiple polyps image in the GB that measure < 1 cm in size. While the data suggests nodules < 1 cm harbor a very low risk of malignancy, most society guidelines suggest imaging follow-up.

(Left) Ultrasound of a 41-year-old man with chest pain shows two 4-mm GB polyps image. Their small size, echogenicity, multiplicity, and stability at follow-up sonography indicate hyperplastic (cholesterol) polyps.

(Right) Ultrasound of a 47-year-old woman shows a 1-cm, pathologically confirmed adenomatous polyp image. The likelihood of neoplasia increases with polyp size, but most GB polyps are hyperplastic.



• Polypoid or sessile mass protruding from gallbladder (GB) mucosa


General Features

• Best diagnostic clue
image Nonmobile hyperechoic mass protruding from GB mucosa without acoustic shadowing

• Location
image GB lumen

• Morphology
image Sessile or pedunculated

Imaging Recommendations

• Best imaging tool
image Ultrasound; endoscopic ultrasound (EUS)

• Protocol advice
image Grayscale and color Doppler US with 6 MHz transducer

CT Findings

• Often difficult to visualize on CT due to lower spatial resolution
image CT underestimates polyp size compared to US

• Best visualized on CECT due to vascularity of polyp
image Can show variable enhancement

image No convincing evidence that polyp enhancement pattern predicts malignancy

• Ill-defined margins of larger polyps possible predictor of malignancy

• Useful for local staging (including lymph node metastases, liver invasion, metastases) in larger polyps where risk of malignancy is high

Ultrasonographic Findings

• Ultrasound is insensitive (only 50%) for polyps, detecting only 1/2 of polyps found at histopathology

• False-positive rate of up to 30%, with positive predictive value of only 10% (compared to histopathology)
image Poor accuracy rates for polyps < 5 mm

image Potentially due to stones, GB folds, sludge, or cholesterolosis mimicking polyps

image Roughly 10% of polyps disappear on follow-up ultrasounds
– Original polyp may have been spurious, but could also reflect polyps breaking off or resolution of inflammatory polyps

• Immobile echogenic mucosal excrescence/nodule, either sessile or lobulated
image No acoustic shadowing, unlike stones

image Highly echogenic foci or “comet tail” artifacts within polyp suggests a cholesterol polyp

image Large polyps may show internal vascularity on color Doppler US

image No clear sonographic features to differentiate benign and malignant polyps
– Questionable link between sessile morphology and malignancy

– Multiple nodules more likely to be benign (usually cholesterol polyps); neoplastic polyps often solitary

• EUS has been shown to have higher accuracy in differentiation of benign (97%) vs. malignant (76%) polyps
image Better demonstration of mucosal invasion

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Nov 16, 2016 | Posted by in GASTROINTESTINAL IMAGING | Comments Off on Gallbladder Polyps
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