IPMN (intraductal papillary mucinous neoplasm) of the pancreas is classified into subtypes based on mucin expression. Which IPMN subtype has the highest risk of invasive carcinoma and worst prognosis?

• A Gastric-type IPMN with MUC5AC expression
• B Intestinal-type IPMN with MUC2 and CDX2 expression
• C Pancreatobiliary-type IPMN with MUC1 expression ✓
• D Oncocytic-type IPMN with GNAS mutation

Explanation

IPMNs are classified by morphology and mucin profile into gastric (most common, low-grade, MUC5AC+), intestinal (MUC2+, CDX2+, colloid carcinoma when invasive — intermediate prognosis), pancreatobiliary (MUC1+, MUC5AC+/−, highest grade dysplasia, invasive tubular/ductal carcinoma — worst prognosis), and oncocytic subtypes. The pancreatobiliary subtype displays the most complex architecture (branching papillae), highest-grade dysplasia, and produces invasive carcinomas with the worst prognosis because the associated invasive component is tubular (conventional ductal-type) carcinoma. Intestinal-type IPMN produces colloid carcinoma when invasive, which has a significantly better prognosis. GNAS mutations (encoding Gαs) are found in ~60–70% of IPMNs of any subtype.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.