Pathology of the gallbladder: A concise review

While often underappreciated, the gallbladder may be affected by a variety of pathological processes that have specific clinical correlates. Reactive epithelial changes within typical cholecystitis may mimic dysplasia. Usual stone-associated cholecystitis has only mild inflammation, but variants of cholecystitis may have abundant xanthoma cells, eosinophils, or lymphocytes and plasma cells. Metaplasia from the normal columnar absorptive epithelium into mucinous epithelium occurs in a subset of cases, and a further subset may progress to dysplasia, which is thought to be the main precursor of invasive gallbladder carcinoma. Unlike the situation in the colon, adenomas in the gallbladder are rare and not likely to be the precursors of most carcinomas. Most invasive carcinomas of the gallbladder present at advanced stage, and therefore are highly lethal. While their morphology may be identical to that of other pancreatobiliary carcinomas, molecular data are emerging to suggest that these neoplasms are genetically distinct. Several more uncommon types of gallbladder carcinoma, such as papillary adenocarcinomas and small cell carcinoma, have different clinical implications, so it is important that they are recognized. p16 and p53 inactivation are consistent findings in gallbladder carcinomas, but novel abnormalities are revealed by recent global genetic analysis of these neoplasms.