Molecular, Histologic, and Radiologic Findings of High-Grade Invasive Adenocarcinoma Arising in Oncocytic Subtype of Intraductal Papillary Mucinous Neoplasm: A Case Report and Review of Literature.

Background: We present a case of adenocarcinoma arising in the oncocytic subtype of intraductal papillary mucinous neoplasm (O-IPMN), with emphasis on the molecular findings in the adenocarcinoma component. Tissue microdissection and next-generation sequencing were performed using a 26 gene panel (AKT1, ALK, APC, BRAF, CDH1, CTNNB1, EGFR, ERBB2, FBXW7, FGFR2, FOXL2, GNAQ, GNAS, KIT, KRAS, MAP2K1, MET, MSH6, NRAS, PDGFRA, PIK3CA, PTEN, SMAD4, SRC, STK11, TP53) of cancer-related genes. Case Presentation: A 69-year-old Caucasian female presented with chest pain and was found to have findings consistent with acute pancreatitis. During her work-up, computed tomography scan revealed a large cystic and solid mass in the tail of the pancreas. She recovered from her acute pancreatitis and was discharged home. She later returned for resection of her mass. Results: Evaluation of three microdissected regions of tumor demonstrated no identifiable nonsynonymous alterations in any of the three regions, within the targeted genes. Conclusion: This case demonstrates that the O-IPMN is a molecularly distinct subtype, and we conclude that adenocarcinoma arising in these neoplasms shows molecularly distinct tumorigenesis from traditional pancreatic ductal adenocarcinoma. These differences may help explain the improved survival with invasive adenocarcinoma arising from these lesions compared with traditional ductal adenocarcinoma.