Gallbladder polypoid lesions, also known as gallbladder augmentation lesions, is a collective term for limited augmentation-like lesions of the gallbladder mucosa. It is classified by pathology: gallbladder cancer, gallbladder adenocarcinoma, gallbladder adenomyosis, and cholesterol polyps. Clinically, there are three types of polyps: cholesterol polyps, benign non-cholesterol polyp-like lesions, and polyp-type early gallbladder cancer.
1.Cholesterol polyp
Cholesterol polyps are formed when cholesterol is deposited in the lamina propria of the gallbladder wall due to dysregulation of cholesterol lipid metabolism, and then bulge into the gallbladder cavity and covered with normal mucosal epithelium. Ultrasound shows that most of the polyps are multiple, less than 10 in diameter, often located at the base of the gallbladder, with strong echogenicity and a large pendulum with a small tip dangling in the gallbladder cavity when adjusted for body position. In case of extensive cholesterol mucosal deposition, the gallbladder wall is thickened due to fibrous tissue hyperplasia and adheres closely to surrounding organs, making separation difficult.
Most patients with cholesterol polyps have no clinical symptoms and the gallbladder functions well, so they only need regular follow-up inspections. No reports of cancer have been found so far.
2.Benign non-cholesterol polypoid lesions
These lesions account for about 36% of the total and include the following.
Adenomas, derived from the proliferation of epithelial components, are masses formed due to adenomatous hyperplasia of the gallbladder mucosa. It is more common and is characterized mostly by a tipped, solitary, papillary shape. The histological classification is: papilloma, ductal adenoma, and mixed adenoma. ultrasound shows: all are moderately echogenic, with unsmooth margins, wide tips, solitary, and greater than 10 in diameter, mostly at the base of the gallbladder. Adenomas have obvious malignant potential and are recognized as precancerous lesions. The process is: adenomatous hyperplasia → moderate to severe adenomatous heterogeneous hyperplasia → carcinoma, with a cancer rate of about 10%. Recent studies have shown that the occurrence of adenoma and cancer of gallbladder is related to the long-term stimulation and damage of gallbladder mucosa by stones and chronic inflammation, resulting in heterogeneous proliferation of epithelial cells. The possibility of cancer should be highly suspected when ultrasound shows the following conditions.
①diameter greater than 10;
② solitary.
③ located in the neck of gallbladder.
④ moderate to low intensity echogenicity.
⑤ accompanied by gallbladder stones. Once cancer is suspected, radical cholecystectomy should be performed as soon as possible.
The pathogenesis of adenomyolipoma, also known as adenomyomatosis of the gallbladder, is unclear. Recent reports and studies on gallbladder histology suggest that the formation of intra-biliary stenosis in adults may be due to incomplete embryonic gallbladder budding, or may be related to impaired gallbladder dynamics, resulting in increased pressure in the gallbladder, causing the mucosa to extend into the submucosa, such as the muscular layer and herniate out to form the Roche-Archis sinus ( RAS). The pathogenesis of RAS is now widely believed to be the result of increased mucosal hyperplasia of the gallbladder, thickening of the gallbladder wall due to muscle hyperplasia, abnormal hyperplasia of nerve fibers in the gallbladder wall, and incomplete embryonic gallbladder budding. Ro-Archis sinuses can reach the plasma membrane surface and are numerous, often with bile stagnation and secondary inflammation forming stones and embedding them. The lesions are divided into the following pathological types according to their location and stage of development: diffuse, segmental, and limited.
(1) Diffuse type
The lesion has epithelial and muscular hyperplasia from the neck to the base, and the RAS involves the whole gallbladder. The cholangiogram shows irregular thickening of the gallbladder wall surrounded by many bead-like or lace-like translucent dots, and if the RAS is large and embedded with stones, a fixed cystic wall filling defect can be seen. As cholesterol deposition, adenomatous hyperplasia and neuromatosis often coexist, some cases may present with concentrated gallbladder function and hyperemptying function, manifesting as persistent pain, dyspepsia and other clinical symptoms.
(2) Segmental type
Initially, the affected cyst wall is circumferentially narrowed, with a width not exceeding 3. At this time, it is also called circumferential glandular hyperplasia, which usually occurs at the site of congenital gallbladder septum and extends to the surrounding gallbladder wall. Cholangiography: 1-2 annular strictures in the gallbladder, dividing the gallbladder into 2-3 connected cavities and showing RAS, which can be located between the cystic duct and the funnel, between the funnel and the intermediate part, and between the intermediate part and the base, depending on the site of the stricture. In the progressive stage, the lesion is still confined to a section of the cystic wall, but the extent is larger, and the cystic wall at the lesion is thickened and narrowed with typical formation of RAS, which can be divided into proximal type, located at the funnel part, distal type, located at the distal base, intermediate type, located at the body of the gallbladder, and intermediate distal type, which is more common, with significant distal thickening and complete separation of the lumen when the gallbladder contracts.
(3) Restricted type
The lesion is located at the base of the gallbladder, but the hyperplasia is not only at the base, divided into three stages, the first stage hyperplasia is outside the septum, poorly developed, the second stage growth is significant, the third stage hyperplasia completely closes the channel, showing a limited papillary mass, the imaging shows: RAS and gallbladder lumen, showing filling defect or crater changes.
Adenomyoma was previously considered to have no propensity for malignancy, but studies in recent years have shown that it still has the potential for carcinoma, especially glioma. mc to affirm it as a precancerous lesion.
Inflammatory polyps, granulomas caused by direct inflammation, are divided into those without epithelial component and those with epithelial component, with medium quality, single or multiple broad-based nodules, about 5 in diameter, with obvious inflammatory changes in the surrounding cystic wall. The pathological features are mainly mesenchymal cell infiltration, and no cancer has been reported.
Adenomatous hyperplasia, also called hyperplastic polyp, is non-tipped, solitary or multiple, with a diameter of about 5. The pathology is characterized by surface hyperplasia, similar to intestinal epithelial metaplasia, with visible smooth muscle bundles and cupped cells.
Other rare lesions: smooth muscle tumor, lipoma, fibroma, hemangioma, neurofibroma, fibrolipoma, fibro-yellow granulomatosis, hepatopancreatic tissue heterogeneity, etc.
3.Polypoid-type early gallbladder cancer
It accounts for about 10% of gallbladder polyp-like lesions and is divided into papillary type and nodular type. Generally, the diameter does not exceed 20, and adenocarcinoma is more common in about 85%. The cause is generally considered to be related to the long-term stimulation caused by the chronic infection of gallbladder stones. About 80% of gallbladder cancer patients are accompanied by gallbladder stones, so gallbladder resection should be performed as early as possible for patients with gallstone disease, especially for elderly patients with obvious clinical symptoms. When benign polyp-like lesions of gallbladder affect the function of gallbladder, the clinical symptoms of patients are often similar to those of cholelithiasis, and most of them are accompanied by chronic inflammation of gallbladder, which are often indications for LC surgery.
For malignant polyp-like lesions of gallbladder, preoperative ultrasound examination is very important, and the endoscopic ultrasound developed in recent years is also very helpful for the diagnosis of gallbladder cancer. When the lesion is larger than 12 mm, we should highly suspect the possibility of malignancy and perform open radical cholecystectomy to remove the loose connective tissue above and below the gallbladder duct together with the fibrofatty tissue in the liver bed.