A comparative study of intraductal papillary neoplasia of the biliary tract and pancreas.

Intraductal papillary mucinous neoplasm of the pancreas is a rare but well-established entity in contrast to intraductal papillary mucinous neoplasm of the biliary tract. The aim of this study was to compare the clinicopathologic features of intraductal papillary mucinous neoplasms of the biliary tract and of the pancreas. Twenty patients who underwent resection for intraductal papillary mucinous neoplasm of the biliary tract were compared with 29 cases resected for intraductal papillary mucinous neoplasm of the pancreas. Clinicopathologic characteristics and resection specimens of all patients were reassessed and immunohistochemically screened for expression of a distinct set of tumor markers. Median ages of patients with intraductal papillary mucinous neoplasms of the biliary tract and of the pancreas were 66 and 62 years, respectively (P < .05). Twelve patients with intraductal papillary mucinous neoplasm of the biliary tract (60%) had neoplasms with infiltrating carcinoma, compared with 6 patients with intraductal papillary mucinous neoplasm of the pancreas (21%, P < .05). Cytokeratin 7 and 20 expressions were equal in biliary and pancreatic intraductal papillary mucinous neoplasms. Cytokeratin 20 expression was mainly found in intestinal-type tumors. Gastric, pancreaticobiliary, and oncocytic subtypes were all observed in the intraductal papillary mucinous neoplasm of the biliary tract group. The distribution was significantly different from the intraductal papillary mucinous neoplasm of the pancreas group. The 3-year overall survival rate of malignant biliary and pancreatic intraductal papillary mucinous neoplasm was 63% and 65%, respectively (P = .798). Positive lymph nodes and a high expression of membranous mucin were associated with a significantly shorter overall survival in patients with malignant intraductal papillary mucinous neoplasm. Finally, p53 and Ki67 proliferation index were both associated with the carcinogenesis of intraductal papillary mucinous neoplasm, whereas DPC4 and CDX2 were not. Clinicopathologic features of intraductal papillary mucinous neoplasm of the biliary tract largely resemble those of intraductal papillary mucinous neoplasm of the pancreas, although intraductal papillary mucinous neoplasm of the biliary tract was associated with a higher malignancy rate at the time of surgical treatment. The level of membranous mucin expression and positive lymph nodes are significant prognosticators in patients with malignant intraductal papillary mucinous neoplasm.