Nonneoplastic Tumors in gallbladder

Cholesterol Polyp/Cholesterolosis
Cholesterol polyps, or cholesterolosis, are the most common gallbladder polyps. The surgical literature refers to cholesterolosis as a “strawberry gallbladder.” They range from solitary to multiple. Gallstones may or may not be present. Cholesterolosis is often an incidental diagnosis, usually made by a pathologist. These polyps are not considered premalignant, although an occasional carcinoma is surrounded by glandular dysplasia and cholesterolosis; the carcinoma probably originates first and tumor epithelium then absorbed cholesterol from bile. Cholesterolosis is not part of the spectrum of acute cholecystitis. No association exists with systemic disorders such as atherosclerosis or diabetes. Even if detected preoperatively, cholesterolosis and adenomyomatosis are not believed to be indications for cholecystectomy. Smaller cholesterol polyps are not detected with unenhanced CT but become evident postcontrast.
Conventional US shows most larger cholesterol polyps to be pedunculated, have a granular surface, and tend toward a hypoechoic appearance, but smaller ones are mostly hyperechoic. Smaller polyps are nonmobile and adhere to the gallbladder wall, and both large and small are without acoustic shadowing. The
smaller ones tend to have a smooth outline; they become irregular with growth. Endoscopic US with its higher resolution is preferred over conventional US when evaluating gallbladder polyps.
Some authors suggest that persistence of gallbladder contrast 24 hours after an oral cholecystogram is indirect evidence of cholesterolosis. No objective data support this statement, and one should not rely on this finding. Although generally not warranted, US-guided percutaneous transhepatic needle aspiration cytology can diagnose cholesterol polyps.
Adenomyoma/Adenomyomatosis Adenomyomatosis presents either as a focal gallbladder narrowing or as diverticular-like outpouchings, most often in the gallbladder fundus. These outpouchings, also called cholecystitis glandularis proliferans, are believed to represent both mucosal herniation into muscularis propria and prominent Rokitansky- Aschoff sinuses. A rare report describes a carcinoma associated with adenomyomatosis, probably being coincidental. Although somewhat controversial, in most patients adenomyomatosis is generally believed not to be associated with symptoms.
In general, an oral cholecystogram provides more information about adenomyomatosis and cholesterolosis than US but is a procedure seldom performed today. Adenomyomatosis tends to be more prominent after a fatty meal and is best seen on a post–fatty meal oral cholecystogram. A number of prior reports of gallbladder diverticula probably describe adenomyomatosis; their imaging differentiation is not clear, although some authors do attempt to differentiate between these two entities. A typical appearance in a contrast-filled gallbladder consists of irregular diverticular-like outpouchings. When subtle, the fine granular outpouchings are difficult to identify with most current imaging techniques. At times imaging reveals a circumferential gallbladder fold resulting in an hourglass appearance. Superficially the latter condition mimics a gallbladder septum. A rare adenomyoma appears polypoid.
Magnetic resonance RARE sequences and breath-hold are superior to other pre- and postcontrast techniques in detecting Rokitansky- Aschoff sinuses. Adenomyomatosis is identified as small intramural foci hypointense on T1- and hyperintense on T2-weighted images. These outpouchings should not enhance postcontrast, but adjacent gallbladder mucosa does enhance, especially if concurrent inflammation is present, and thus the occasional description of adenomyomatosis as hypointense spots in a more hyperintense gallbladder wall. Small outpouchings blend into the gallbladder wall and result in a not uncommon postcontrast appearance of homogeneous, continuous wall enhancement.
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Radiology images of T2–weighted image of adenomyomatosis. The gallbladder contains a transverse fold (arrow) and several gallstones (arrowhead). The pancreatic and bile ducts are dilated secondary to a pancreatic cancer.
Hyperplastic/Inflammatory Polyp Macroscopic hyperplastic polyps are uncommon, although an occasional large one is detected. Larger ones tend to enhance with contrast and angiography may even reveal neovascularity and a tumor stain. Ectopic Tissue (Pancreatic or Gastric) Heterotopic gastric mucosa or pancreatic tissue is occasionally found in the gallbladder. Most e polypoid, often located in the fundus. Ultrasonography reveals an echogenic polyp in the gallbladder.
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