Often classified as having high-grade dysplasia given architectural complexity
• Neoplastic cells have abundant granular eosinophilic cytoplasm with large nuclei, prominent nucleoli
• Both intracytoplasmic and intercellular lumina found, many containing mucin, with scattered goblet cells
• Stroma can be edematous or myxoid at tip &/or base of papillae
• Invasive carcinoma, often minimally invasive, present in 25-50%
• Stain strongly with MUC6
• Variable staining with MUC1, MUC2, MUC5AC, CEA, CA19-9
Gross Appearance A tan-red luminal papillary mass partially involves the dilated main pancreatic duct .
Dilated Branch Duct Intraductal oncocytic papillary neoplasms (IOPNs) consist of architecturally complex, thick papillae, seen here growing in a dilated branch duct that is, in part, lined by relatively flat epithelium .
Higher Magnification Higher magnification of IOPN exhibits architecturally complex growth with cribriforming &/or solid nests. The neoplastic epithelial cells have abundant granular eosinophilic cytoplasm and large nuclei with prominent nucleoli.