A case of gallbladder adenocarcinoma arising in association with intracystic papillary neoplasm (ICPN) with abundant mucin production.

Intracystic papillary neoplasm (ICPN) of the gallbladder is a rare clinicopathological entity with a wide range of malignant potentials. Here, we report a case of mucin-producing gallbladder carcinoma possibly derived from ICPN. A 78-year-old female patient was referred to our hospital for examination of jaundice. Abdominal CT showed dilated biliary trees and a contrast-enhanced large polypoid mass in the gallbladder. Duodenoscopy showed a large amount of mucin extravasating from the ampulla of Vater. Bile cytology showed no evidence of malignancy. Under the diagnosis of mucin-producing gallbladder tumor, we performed laparoscopic cholecystectomy. Macroscopically, there was a large papillary tumor throughout the entire gallbladder mucosa. Pathological examinations showed a gallbladder adenocarcinoma localized to the mucosa in association with ICPN. Immunohistochemical analysis of the tumor revealed positive staining for MUC2 and MUC5AC but negative for MUC1 and MUC6, suggestive of the intestinal type.