Intraductal Papillary Mucinous Carcinoma With No Overt Mucin Production

Abstract

A 62-year-old man presented with a solid and cystic mass in the tail of the pancreas detected on computed tomography during a workup for nausea and vomiting. A distal pancreatectomy, along with a partial gastrectomy and splenectomy, was performed. The mass invaded the stomach wall and did not have copious mucin typical of many intraductal neoplasms. Microscopically, a neoplasm containing epithelium with pleomorphism, frequent mitotic figures, and a blunt pattern of invasion was present, best classified as a pancreatobiliary-type intraductal papillary mucinous carcinoma. An intraductal papillary mucinous neoplasm (IPMN) is a grossly or radiographically detectable proliferation of the main pancreatic duct or one of its major branches, typically larger than 1.0 cm. Intraductal papillary mucinous neoplasms are categorized as intestinal, gastric, or pancreatobiliary based on the epithelium in the papillary component. They may be associated with various degrees of dysplasia and even invasive carcinoma. Mucin glycoprotein and CDX2 immunohistochemistry can be useful in distinguishing epithelial types. Differential diagnostic considerations include retention cysts, pancreatic intraepithelial neoplasia, mucinous cystic neoplasms, serous cystic neoplasms, intraductal tubulopapillary neoplasms, acinar cell carcinoma, and intraductal oncocytic papillary neoplasms. Intraductal papillary mucinous neoplasms exhibit a spectrum of gross and microscopic features, differential diagnostic considerations, ancillary techniques available for IPMN characterization, and genetic associations; awareness of these characteristics are important to those who are studying IPMN and who are considering IPMN in their diagnosis of a pancreatic neoplasm.