Gallbladder polyps, cholesterolosis, adenomyomatosis, and acute acalculous cholecystitis.

Acute acalculous cholecystitis is characterized by acute inflammation of the gallbladder in the absence of stones, usually occurring in elderly and critically ill patients with atherosclerosis, recent surgery or trauma, or hemodynamic instability. Patients may present with only unexplained fever, leukocytosis, and hyperamylasemia without right upper quadrant tenderness. If untreated, rapid progression to gangrene and perforation occurs. Surgical cholecystectomy and cholecystostomy provide the most definitive treatment although recent studies indicate success with percutaneous or endoscopic cholecystostomy. Cholesterolosis and adenomyomatosis of the gallbladder are usually clinically silent and incidental findings at the time of cholecystectomy. Cholesterolosis is characterized by mucosal villous hyperplasia with excessive accumulation of cholesterol esters within epithelial macrophages. Usually clinically silent, the condition rarely is associated with biliary symptoms or idiopathic pancreatitis and cannot reliably be detected by ultrasonography. Adenomyomatosis describes an acquired, hyperplastic lesion of the gallbladder characterized by excessive proliferation of surface epithelium with invaginations into a thickened muscularis propria. Ultrasonography may reveal a thickened gallbladder wall with intramural diverticula. Adenomyomatosis may portend a higher risk of gallbladder malignancy. Most cases of cholesterolosis and adenomyomatosis identified by imaging require no specific treatment. Gallbladder polyps include all mucosal projections into the gallbladder lumen and include cholesterol polyps, adenomyomas, inflammatory polyps, adenomas, and other miscellaneous polyps. Most polyps are nonneoplastic and rarely cause symptoms. Cholecystectomy is advocated for polyps greater than 10 mm in size because of increased risk of adenomatous or carcinomatous features.