Pathological characteristics of intraductal polypoid neoplasms of bile ducts in Thailand.

Intraductal papillary or tubular neoplasms of the bile duct have recently been proposed as one of the pre-invasive lesions of cholangiocarcinoma. Herein, a total of 50 cases of intraluminal polypoid neoplasms of the bile ducts experienced in Khon Kaen University Hospital in Thailand were pathologically examined. These cases presumably had a history of infection of Opisthorchis viverrini. These neoplasms were histologically composed of high-grade intraepithelial neoplasm showing a tubular and/papillary pattern without invasion (20 cases), and with minimal and considerable invasion (15 and 15 cases, respectively). They were histologically classifiable into papillary type (10 cases), tubular type (20 cases) and papillotubular type (20 cases), and were phenotypically classifiable into gastric (17 cases), intestinal (17 cases) and pancreatobiliary types (16 cases). It was found that cases of papillary type and gastric or intestinal phenotype were less invasive, while those of tubular or papillotubular type and pancreatobiliary phenotype were more invasive. In conclusion, intraductal polypoid neoplasms in Thailand were well-differentiated papillary and/or tubular neoplasms including those with no or minimal invasion, and histological and phenotypic subclassifications seem to be useful for evaluation of the aggressive pathological behaviors of these neoplasms.