Gallbladder polyps are mucosal projections extending from the gallbladder wall into the lumen. The vast majority (60-90%) are cholesterol polyps and are benign in nature. True neoplastic polyps (adenomas) are rare and carry malignancy potential. On US, they appear as echogenic structures attached to the wall, immobile, and without acoustic shadow. Size is the most critical risk factor: malignancy risk increases in polyps >10 mm. Key differentiation from gallstones: polyps are immobile, stones are mobile.
Age Range
30-70
Peak Age
50
Gender
Equal
Prevalence
Common
The most common type of gallbladder polyps are cholesterol polyps (60-90%). These result from excessive cholesterol ester accumulation in submucosal macrophages — lipid-laden macrophages (foam cells) form small pedunculated or sessile projections in the mucosa. These polyps are not true neoplasms and carry no malignancy risk. On US, small size (<5 mm), multiple, and pedunculated appearance suggests cholesterol polyp. Inflammatory polyps result from granulation tissue proliferation due to chronic inflammation. True adenomatous polyps are dysplastic epithelial proliferations and may follow the adenoma-carcinoma sequence — size >10 mm, sessile morphology, solitary structure, and age >50 increase malignancy risk. The absence of acoustic shadow in polyps results from their soft tissue structure — they lack the strong absorption of crystalline structure found in stones.
Cardinal US finding of gallbladder polyps: wall-attached, not moving with position change (immobile), echogenic structure without acoustic shadow. This triad differentiates polyp from stone (mobile + acoustic shadow) and sludge (mobile + low echogenicity). Immobility test: confirmed by turning patient to decubitus or semi-erect position to verify the lesion does not change its position on the wall.
Echogenic structure extending from gallbladder wall into the lumen, not moving with position change (immobile), without acoustic shadow. Cholesterol polyps typically show multiple, small, and bright echogenicity.
Report Sentence
An immobile echogenic polypoid lesion measuring … mm extending from the gallbladder wall into the lumen is seen without acoustic shadow.
A thin vascular pedicle (feeding vessel) may be visible in pedunculated polyps on Doppler US. Cholesterol polyps usually show no or minimal vascularity, while adenomatous polyps may show more prominent vascularity.
Report Sentence
A vascular pedicle is seen in the polypoid lesion on Doppler US.
Enhancing polypoid lesion in the gallbladder lumen on contrast-enhanced CT. CT is less sensitive than US for polyp detection but useful for evaluating wall invasion and relationship with surrounding structures in large polyps (>10 mm).
Report Sentence
An enhancing polypoid lesion (… mm) is seen in the gallbladder on contrast-enhanced CT.
Polypoid lesion showing lower signal than bile fluid on T2-weighted MRI. Shows enhancement on contrast-enhanced sequences. MRI may help differentiate cholesterol polyp vs adenomatous polyp.
Report Sentence
A polypoid lesion (… mm) is seen in the gallbladder on T2-weighted MRI.
Multiple small (<5 mm) polypoid lesions — suggestive of cholesterol polyps. Usually located in fundus or body. All are immobile and without acoustic shadow.
Report Sentence
Multiple small polypoid lesions are seen in the gallbladder, consistent with cholesterol polyps.
Solitary, broad-based (sessile), >10 mm polypoid lesion — suspicion of adenomatous polyp or early carcinoma. Irregular surface and heterogeneous echogenicity are additional warning signs.
Report Sentence
A solitary sessile polypoid lesion measuring … mm is seen in the gallbladder; further evaluation is recommended to exclude adenomatous polyp/early carcinoma given its size and morphology.
Criteria
Most common type (60-90%). Composed of lipid-laden macrophages. Usually <10 mm, multiple, pedunculated.
Distinct Features
Small, bright echogenic, multiple, no acoustic shadow or vascularity. No malignancy risk.
Criteria
True neoplastic polyp. Dysplastic epithelial proliferation. Carries malignancy potential (adenoma-carcinoma sequence).
Distinct Features
Usually solitary, sessile, >10 mm. More prominent vascularity on Doppler. Cholecystectomy indication.
Criteria
Granulation tissue proliferation due to chronic inflammation. Usually in the setting of chronic cholecystitis.
Distinct Features
May be accompanied by wall thickening. Sessile or pedunculated. Low malignancy risk.
Distinguishing Feature
Gallstones are mobile (move with position change) and create acoustic shadow. Polyp is immobile and has no acoustic shadow.
Distinguishing Feature
Sludge is mobile and low-echogenicity, polyp is immobile and higher echogenicity. Tumefactive sludge may confuse — differentiated by Doppler (avascular) and follow-up US.
Distinguishing Feature
In adenomyomatosis, focal wall thickening (fundal type) may appear polypoid but comet-tail artifact and intramural cystic spaces are pathognomonic.
Distinguishing Feature
Carcinoma shows wall invasion, liver extension, lymphadenopathy, and heterogeneous enhancement. Polyp shows no invasion findings. Differentiation between >10 mm sessile polyp and early carcinoma may be difficult — cholecystectomy is recommended.
Urgency
surveillanceManagement
conservativeBiopsy
Not NeededFollow-up
6-monthManagement of gallbladder polyps is determined by size and risk factors. No follow-up needed for <6 mm polyps without risk factors. 6-month interval US follow-up is recommended for 6-9 mm polyps. Cholecystectomy is indicated for ≥10 mm polyps or polyps showing rapid growth (size increase in <2 years). Risk factors: age >50, solitary polyp, sessile morphology, accompanying gallstones, PSC. Biopsy is not performed — pathological examination is on the surgical specimen. Cholesterol polyps carry no malignancy risk but definitive differentiation from adenomatous polyp cannot be made with US.
Cholesterol polyps (<10 mm) are benign and require follow-up. Polyps >10 mm warrant cholecystectomy due to adenoma or early carcinoma risk. 6-10 mm polyps are followed with 6-monthly US. Risk factors: >50 years, solitary, sessile, growing.