Unusual types of gallbladder carcinoma. A report of 16 cases.

In a review of 159 gallbladder carcinomas, we identified four unusual histologic types: oat-cell carcinoma (five cases), giant-cell adenocarcinoma (seven cases), intestinal-type adenocarcinoma (three cases), and adenocarcinoma with choriocarcinoma-like areas (one case). Oat-cell carcinomas were similar at light- and electron-microscopic levels to those previously described in other anatomic locations. Giant-cell adenocarcinomas coexisted with well-differentiated adenocarcinomas and exhibited transition areas. For these reasons, we believe that they originate from preexistent adenocarcinomas. Intestinal-type adenocarcinomas consisted predominantly of goblet cells or glandular structures similar to colonic crypts. These four histologic types of gallbladder carcinoma were more common in women than in men, usually coexisted with lithiasis, and had a highly aggressive clinical behavior. Fourteen patients died of direct local extension and metastases, and two were unavailable for follow-up.