Gall bladder polyp and other incidental biliary findings

Recommended follow-up of small polyps (<10 mm) varies from author to author. A commonly accepted strategy includes:

• ≤ 6 mm: no further follow up necessary

• 7-9 mm: follow-up to ensure no interval growth; follow-up interval varies from 3 to 6 months

• ≥ 10 mm: surgical consultation

  • usually warrants cholecystectomy

  • if no cholecystectomy, annual follow up is warranted

Lower thresholds for follow up or intervention may be warranted if one's patient population is known to have a higher risk of gallbladder carcinoma (e.g. higher incidences in Pakistan, Ecuador, or females in India).

ACR GUIDELINE

Notes:

1. Porcelain Gallbladder: Large retrospective studies have shown that the prevalence of malignancy in resected porcelain

gallbladders is 5-7% compared to 0.6 - 0.8% in the general population. Incidence of new cancer in a porcelain gallbladder

is likely to be < 1% per year (inferred from available data); only a small fraction of this would likely be detected and

treated differently if yearly follow-up were done. Therefore, the committee generally does not recommend follow-up.

2. Diffuse gallbladder wall thickening: In the absence of one of the above-mentioned secondary causes, a primary cause

should be excluded by clinical history. If the thickening is uniform or nearly so, the risk for an underlying malignancy is

negligible.

3. Polyps: Evidence for their management is inconclusive and based on ultrasound; the authors infer that this data is also

applicable to CT and MRI. One study of 346 patients with gallbladder polyps found no malignancies and only one polyp

7-9 mm in size and two polyps > 10mm. Another study of 467 patients found that only 6.6% of polyps grew, and 3.7%

were malignant or had malignant potential, including benign adenomatous and dysplastic potential. Only 0.7% were

frankly malignant. The authors recommended follow-up for polyps 5-10 mm in size.

4. Biliary duct dilatation: Defined as > 6 mm in a patient < 60 years of age with the gallbladder present, or a common

bile duct > 10 mm with the gallbladder absent. Because biliary dilatation is often chronic and asymptomatic, liver function

tests (alkaline phosphatase, bilirubin) can help assess the importance of this finding. If there is suspicion of a biliary tract

mass, MRCP may be performed. However, if the suspected mass is in the lower third of the common bile duct, endoscopic

ultrasound (EUS) or ERCP-guided FNA may be preferred as the first option.

Source: White Paper: Managing Incidental Findings on Abdominal/Pelvic CT and MRI, Part 4:

Gallbladder and Biliary Findings, JACR, December 2013