What is the malignancy risk of a 7 mm gallbladder polyp in a 65-year-old patient?

From the Guidelines

A 7 mm gallbladder polyp in a 65-year-old patient carries a low to moderate risk of malignancy, and according to the most recent guidelines, no follow-up is recommended for polyps of 9 mm or smaller, but close monitoring is still warranted due to the patient's advanced age. The risk of malignancy in gallbladder polyps is generally associated with the size of the polyp, with polyps smaller than 10 mm having a lower risk of malignancy, approximately 0-3% 1. However, the patient's age is a significant factor, as the risk of malignancy increases with age.

Key Considerations

• The patient's age (65 years) increases the concern for malignancy, despite the polyp being smaller than 10 mm.
• The most recent guidelines from the Society of Radiologists in Ultrasound consensus conference recommend no follow-up for polyps of 9 mm or smaller, but this does not account for the patient's age 1.
• Close monitoring with follow-up ultrasound in 3-6 months is recommended to assess for any growth or changes in characteristics, as growth of 4 mm or more within 1 year constitutes rapid growth and may indicate an increased risk of malignancy 1.
• Any polyp in a patient with risk factors such as primary sclerosing cholangitis, a porcelain gallbladder, or a history of familial polyposis syndromes would further elevate the malignancy risk and might justify more aggressive management.

Management Recommendations

• Close monitoring with follow-up ultrasound in 3-6 months to assess for any growth or changes in characteristics.
• If the polyp shows growth, develops concerning features (such as irregular borders or internal vascularity), or if the patient develops symptoms like right upper quadrant pain, cholecystectomy (surgical removal of the gallbladder) should be considered.
• The patient's age and any additional risk factors should be taken into account when determining the management plan, and a more aggressive approach may be warranted in certain cases 1.

From the Research

Malignancy Risk of Gallbladder Polyps

• The malignancy risk of gallbladder polyps is a concern, especially for polyps larger than 10 mm 2, 3.
• A study of 1204 patients with polypoid lesions of the gallbladder found that 20.1% of surgical patients had malignant polyps, with malignant polyps being significantly larger than benign lesions (means: 27.5 ± 18.4 mm vs. 12.3 ± 12.3 mm, respectively, p < 0.001) 2.
• However, the study also noted that 5% of malignant polyps were 3-5 mm in size, and 8% were 5-10 mm in size, highlighting the potential for malignancy in smaller polyps 2.
• Another study found that malignancy can be present in polyps <10 mm, although it is significantly more frequent in polyps >10 mm 3.
• A case report described a 7 mm gallbladder polyp with carcinoma in situ, highlighting the potential for malignancy in small polyps 4.
• The overall incidence of malignancy in gallbladder polyps is low, with one study finding that only 1.5% of patients with gallbladder polyps had gallbladder malignancy ≥pT1b 5.

Size and Malignancy Risk

• The size of the polyp is an important factor in determining the malignancy risk, with larger polyps being more likely to be malignant 2, 3.
• However, smaller polyps can also be malignant, and the size alone is not a reliable indicator of malignancy 2, 4.
• A study found that the negative predictive value for gallbladder malignancy was 92.8% based on a size ≥10 mm and 100% based on a size ≥3 mm 2.

Management of Gallbladder Polyps

• The management of gallbladder polyps depends on the size and symptomatology of the polyp, as well as the presence of other risk factors for malignancy 2, 3, 5.
• Cholecystectomy is generally recommended for polyps ≥10 mm or for symptomatic polyps, regardless of size 2, 3, 5.
• For smaller, asymptomatic polyps, regular follow-up with ultrasound is often recommended, although the optimal follow-up schedule is not well established 3, 6.