Gallbladder polyps are growths that form on the inner lining of the gallbladder, a small organ located beneath the liver. These growths are frequently discovered incidentally during imaging tests performed for other health concerns. While polyps are relatively common, affecting an estimated 4% to 7% of adults, the vast majority are benign, meaning they are not cancerous.
Factors Influencing Polyp Growth
Gallbladder polyp growth varies by type and other factors. Most polyps are cholesterol polyps, which are cholesterol deposits on the gallbladder wall. These cholesterol polyps typically do not grow significantly and are almost always benign. They account for the largest proportion of gallbladder polyps, ranging from 60% to 90% of all cases.
Another type, inflammatory polyps, are scar tissue formations resulting from chronic inflammation of the gallbladder wall. These polyps also have no association with gallbladder cancer. True polyps, such as adenomas, are less common but are considered neoplastic lesions. While initially benign, they can grow over time and, in rare instances, become cancerous.
Several factors beyond polyp type can influence their growth and overall significance. The size of the polyp at the time of detection is an important consideration, as is the patient’s age; polyps are more common in individuals over 50. The number of polyps present can also be relevant; benign polyps are more likely to appear in multiples, whereas malignant polyps tend to be solitary. While most polyps grow slowly, typically less than 2 millimeters per year, a rapid increase in size is generally considered a concerning development.
Assessing Malignancy Risk
The potential for a gallbladder polyp to be or become cancerous is primarily linked to its size and growth characteristics, with size being the most significant indicator of malignant potential. Small polyps, generally those less than 10 millimeters in diameter, are unlikely to be cancerous, with the risk of malignancy for polyps 10 millimeters or less estimated to be very low, around 0.60%. However, the risk increases with size, and polyps larger than 10 millimeters are considered to have a higher risk of malignancy.
Rapid growth of a gallbladder polyp is another strong indicator. An increase in size of 2 millimeters or more within a year, or 3 millimeters or more per year, is often considered a red flag for increased risk. This kind of growth may suggest a neoplastic change, even if the polyp is not yet at the 10-millimeter threshold. Other factors that raise suspicion include a single lesion, patient age over 50 or 60 years, and a sessile morphology (broad-based rather than stalked). The presence of certain co-existing conditions, such as primary sclerosing cholangitis or gallstones, can also heighten the concern for malignancy.
Monitoring and Treatment Approaches
The management of gallbladder polyps depends on their size, growth pattern, and associated risk factors. For smaller polyps, particularly those less than 5 millimeters without additional risk factors, active follow-up may not be required. However, for polyps between 5 and 9 millimeters, or smaller polyps with risk factors such as age over 60, Asian ethnicity, or primary sclerosing cholangitis, regular surveillance with ultrasound is typically recommended. The frequency of these follow-up ultrasounds can vary, often starting with examinations at 6 months, 1 year, and 2 years. Monitoring can be discontinued if the polyp remains stable in size over a two-year period or if it disappears.
Surgical removal of the gallbladder (cholecystectomy) is generally recommended for polyps 10 millimeters or larger due to increased malignancy risk. Cholecystectomy is also advised if a polyp shows rapid growth (an increase of 2 millimeters or more within two years) or reaches 10 millimeters during surveillance. Even smaller polyps may warrant surgical consideration if they cause symptoms like pain, which can indicate underlying inflammation or other gallbladder issues. Decisions regarding monitoring or surgical intervention are made in consultation with a healthcare professional, considering the patient’s risk profile and overall health.