Intraductal tubular neoplasms of the pancreas: an overview

• True pancreatic intraduct tubular neoplasms are uncommon.
• They include intraductal papillary mucinous neoplasms, intraductal tubular adenoma, and intraductal tubular carcinoma or intraductal tubulopapillary neoplasm.
• Intraductal tubular adenoma is considered a variant of gastric-type intraductal papillary mucinous neoplasm.
• Intraductal tubular carcinoma is included within the rubric of intraductal tubulopapillary neoplasm.

Intraductal lesions of the pancreas are an uncommon but increasingly recognized group of entities mainly because of advances in imaging technology. In the past, precise categorization and understanding of true pancreatic intraduct neoplasms were hampered not only by their relative rarity but also because of the plethora of terminology and criteria used in nomenclature and diagnosis. Although significant progress has been made in the characterization of some of these lesions, as exemplified by intraductal papillary mucinous neoplasms, understanding of the rare intraductal tubular adenoma (ITA) and intraduct tubular carcinoma (ITC) continues to evolve. By definition, these are a group of intraductal, radiologically detectable neoplasms that can progress to or be associated with invasive adenocarcinoma and, as such, are precursor lesions to pancreatic ductal adenocarcinoma. Their often shared clinical and radiological features make precise histological diagnosis essential for appropriate management and optimal outcome. We provide an overview of these neoplasms and highlight recent developments in the understanding of ITA and ITC which have led to ITA being considered a variant of gastric-type intraductal papillary mucinous neoplasms and ITC being encompassed within the intraductal tubulopapillary neoplasm category. We also emphasize the distinguishing histological features to aid diagnosis of these rare lesions.