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Page 2 of 11 Sullivan et al. Mini-invasive Surg 2023;7:15 https://dx.doi.org/10.20517/2574-1225.2022.106

[6]
[5]
adenomatous polyps or malignant polyps . Pseudopolyps make up the majority of gallbladder polyps and
are considered to be benign. While adenomas are also benign, there is some evidence that they can
[7-9]
potentially transform into malignant . The natural history of gallbladder polyps has been investigated in
several long-term US follow-up studies. Studies with 8-11 years of follow-up for small gallbladder polyps
less than 6 mm showed that up to about one-third of patients no longer have visible polyps on the long-
term follow-up US [4,10,11] . However, another long-term follow-up of 20 years of gallbladder polyps
demonstrated that even for small polyps less than 6 mm, growth of 2 mm or greater is not uncommon .
[12]

The treatment of gallbladder polyps with potentially a high risk of transforming into or containing
adenocarcinoma is important, given the markedly improved survival of gallbladder cancer when detected in
earlier stages compared to T3 or later lesions. Factors associated with increased risk of malignancy include
older age, sessile polyp, single or unifocal polyp, larger size, a growth rate greater than 3 mm per year, Asian
or Indian ethnicity, hyperlipidemia, and symptoms [6,13-17] . For example, Asian patients have been reported to
[18]
have a rate of malignant gallbladder polyps of 14%, vs. 6% for European patients . An additional identified
risk factor for malignancy in gallbladder polyps is primary sclerosing cholangitis, with these patients
demonstrating a greater than 50% rate of malignancy in gallbladder masses ranging from size 0.5 cm to over
3.0 cm [19,20] . However, these studies were small (less than 20 patients each) and retrospective in nature. There
is mixed evidence as to whether gallstones are a risk factor for gallbladder cancer in patients with
gallbladder polyps [17,21] . One study used a scoring system consisting of the presence of age greater than 50,
symptoms, polyp size greater than 12.5 mm, single polyp, gallstones, and gallbladder wall thickness and
demonstrated that when less than 4 of these factors were present, the rate of neoplastic polyp was less than
1%, while if 4 or more were present, the rate of neoplastic polyp was 63% . A recent meta-analysis
[22]
exhibited a low risk of gallbladder cancer in polyps less than 10 mm in size, showing that in studies with at
least moderate quality, 4.6 cancers per 10,000 patients were detected in polyps less than 10 mm . The risk
[23]
[18]
of gallbladder cancer in polyps less than 6 mm appears to be extremely small and essentially zero .
However, the management of intermediate-sized gallbladder polyps is somewhat controversial, as even
[14]
polyps less than 10 mm may be true or neoplastic polyps and other studies have shown a small but
nonzero risk of malignancy in polyps less than 10 mm [18,24] , while conversely other studies including the
largest cohort study of over 35,000 patients with gallbladder polyps over 20 years have seen none or
exceptionally rare gallbladder cancer cases in polyps less than 10 mm [12,25] .

MANAGEMENT OF GALLBLADDER POLYPS
Several different societies have published guidelines for the management of gallbladder polyps. The most
recent guidelines from the Society of Radiologists in Ultrasound (SRU) focus on characteristics of the polyp
and recommend cholecystectomy for polyps ≥ 15 mm or ≥ 7 mm if focal wall thickening is also present, and
US surveillance for polyps 10-14 mm and polyps 7-9 mm the polyp is sessile or pedunculated with a thick
stalk. No follow-up is needed for pedunculated polyps that are less than 10 mm in size and also have a thin
stalk. The European guidelines recommend cholecystectomy for polyps that are symptomatic or ≥ 10 mm.
These guidelines stratify patients with risk factors including age ≥ 60 years, primary sclerosing cholangitis,
Asian ethnicity, and sessile lesion including focal gallbladder wall thickening ≥ 4 mm. For patients with
small polyps and no risk factors, no follow-up is needed. For patients with small polyps and risk factors,
surveillance is recommended. Finally, for patients with 7-9 mm polyps without risk factors, surveillance is
recommended, but if a risk factor is present, then cholecystectomy is recommended. The Canadian
Association of Radiologists (CAR) follows the American College of Radiology (ACR) white page
recommendations with no follow for small polyps, US surveillance for polyps 7-9 mm, and cholecystectomy
for polyps ≥ 10 mm.