Gallbladder polyps are growths protruding from the inner lining of the gallbladder, a small organ beneath the liver that stores bile. Most are benign, but a small percentage can be or become malignant. Understanding their characteristics helps determine the appropriate course of action, as some types carry a risk for cancer development.
Understanding Gallbladder Polyps
Gallbladder polyps are common, affecting 4% to 7% of adults, and are often discovered incidentally during imaging. These growths categorize into pseudopolyps and true polyps. Pseudopolyps, making up 60% to 90% of cases, are typically cholesterol deposits and do not have malignant potential. Inflammatory polyps, another pseudopolyp type, are scar tissue from chronic inflammation and also lack cancerous potential.
True polyps, however, represent abnormal cell growth. They include adenomas, which are benign tumors composed of cells similar to the biliary tract lining. Although initially benign, adenomas carry a small risk of transforming into cancer. Adenomyomatosis is another polyp-like condition, characterized by an overgrowth of the gallbladder lining and cyst formation within the wall. While its cancerous potential is debated, adenomyomatosis is generally considered a benign change.
Assessing Cancer Risk
The potential for a gallbladder polyp to be or become cancerous is a key concern. Polyp size is a key indicator of risk. Polyps smaller than 5 millimeters are rarely cancerous, with a very low malignancy rate. However, risk increases with size; polyps larger than 10 millimeters have a greater likelihood of being malignant or developing into cancer. Polyps exceeding 18-20 millimeters carry a substantial risk of malignancy.
Rapid growth also signals increased risk, with an increase of 2 millimeters or more within a year often prompting further evaluation. Certain polyp types, specifically adenomas, have known malignant potential, unlike cholesterol or inflammatory polyps. Patient age is another factor, as individuals over 50 may have a higher risk of malignant polyps. The presence of primary sclerosing cholangitis (PSC) significantly elevates risk, often leading to cholecystectomy recommendations regardless of polyp size.
Detection and Follow-Up
Gallbladder polyps are often discovered incidentally during imaging for other health concerns, as most do not cause symptoms. Abdominal ultrasound is the primary diagnostic tool, providing clear images of the gallbladder and its internal structures. It identifies the presence, size, and location of polyps.
For further characterization or inconclusive ultrasound findings, other imaging techniques like computed tomography (CT) scans or magnetic resonance imaging (MRI) may be used. These advanced methods offer detailed views, helping differentiate polyp types or assess for malignancy. For polyps not immediately removed, regular follow-up imaging, typically with ultrasound, monitors for changes in size or appearance, indicating a risk profile change. Follow-up frequency depends on the polyp’s initial characteristics and associated risk factors.
Treatment Approaches
The management of gallbladder polyps depends on their size, type, presence of symptoms, and associated risk factors. For small, asymptomatic polyps, particularly those less than 5-6 millimeters and without risk factors for malignancy, observation with periodic ultrasound monitoring is often the recommended approach. This watchful waiting strategy allows healthcare providers to track the polyp’s behavior over time. If a polyp grows by 2 millimeters or more within a 2-year period, or if it reaches a size of 10 millimeters, surgical intervention may be considered.
Surgical removal of the gallbladder, known as a cholecystectomy, is the definitive treatment for polyps that pose a higher risk. This procedure is typically recommended for polyps greater than 10 millimeters due to their increased likelihood of malignancy. Cholecystectomy is also advised for smaller polyps (e.g., 6-9 millimeters) if the patient has other risk factors such as being over 60 years old, having primary sclerosing cholangitis, or if the polyp has a sessile (flat) morphology. Additionally, if a polyp causes symptoms like abdominal pain, cholecystectomy may be suggested, especially if other causes for the symptoms have been ruled out. While polypectomy (removal of just the polyp) exists, cholecystectomy is more common for gallbladder polyps, particularly those with malignant potential.