Intraductal Tubulopapillary Neoplasm of the Pancreas: An Overview.

Intraductal tubulopapillary neoplasm is a rare tumor that the World Health Organization recognized in 2010 as a subtype of premalignant pancreatic neoplasms. It is important to distinguish it from other intraductal neoplasms, including intraductal papillary mucinous neoplasm, pancreatic ductal adenocarcinoma, and intraductal variant of acinar cell carcinoma, because intraductal tubulopapillary neoplasm has a favorable prognosis. Histopathologically, intraductal tubulopapillary neoplasms are characterized by tubulopapillary growth, uniform high-grade cytologic atypia, frequent necrotic foci, evident ductal differentiation, and absence of mucin. Intraductal tubulopapillary neoplasms show distinct immunohistochemical and molecular findings, with positive cytokeratin 7, cytokeratin 19, MUC1, and MUC6, and somatic PIK3CA mutations (2 of 11; 18%), and low rates of KRAS (2 of 20; 10%), TP53 (5 of 22; 23%), and BRAF (2 of 13; 15%) mutations. These differences also highlight the fact that intraductal tubulopapillary pancreatic neoplasm is distinct from other similar neoplasms.