Endoscopic Ultrasound‐Guided Fine Needle Aspiration Diagnosis of Pancreatic Intraductal Tubulopapillary Neoplasm: A Cytology Case Report

Intraductal tubulopapillary neoplasm (ITPN) is a rare pancreatic intraductal tumor and recognized precursor of pancreatic ductal adenocarcinoma, accounting for less than 1% of pancreatic exocrine neoplasms and about 3% of intraductal pancreatic neoplasms. Herein, we report an 82-year-old woman with a pancreatic head mass and miliary pulmonary nodules radiologically concerning for pancreatic adenocarcinoma, evaluated by endoscopic ultrasound-guided fine-needle aspiration. Cytology revealed a hypercellular specimen with papillary fronds and clusters of cells arranged in tubular formations with no extracellular as well as intracellular mucin identified; cell block sections showed tubular, cribriform, and papillary architecture with focal high-grade dysplasia. Immunohistochemistry demonstrated diffuse MUC1 positivity with patchy CK7 and CK19 expression and negativity for MUC2, GATA3, and TTF-1, supporting a diagnosis of ITPN. This case highlights the cytomorphologic and immunophenotypic features of pancreatic ITPN on FNA and emphasizes the importance of distinguishing it from intraductal papillary mucinous neoplasm and other pancreatic neoplasms in limited cytology samples.