Intestinal-type adenocarcinoma of the gallbladder. A clinicopathologic study of seven cases.

Seven examples of a distinctive morphological variant of well-differentiated adenocarcinoma of the gallbladder with intestinal features are reported. Four tumors were composed predominantly of goblet cells and absorptive columnar cells, two of which had, in addition, a few Paneth cells and neuroendocrine cells. Three neoplasms closely resembled colonic carcinoma, and one of these also contained neuroendocrine cells. Serotonin-immunoreactive cells were demonstrated in three of the seven intestinal-type adenocarcinomas, two of which also had cells that stained for somatostatin pancreatic polypeptide and cholecystokinin. Four adenocarcinomas were associated with cholelithiasis, and three with intestinal metaplasia of the uninvolved mucosa. Despite the well-differentiated character of all neoplasms and the deceptively benign microscopic appearance of two of them, three patients died with extension to the liver and metastasis. Of the two survivors, one had carcinoma in situ and the other had a carcinoma that extended only to the muscle layer of the gallbladder. The various cell phenotypes found in these gallbladder adenocarcinomas can be explained on the basis of intestinal differentiation.