[1555] Intraductal Papillary Neoplasm of the Bile Duct (IPN): Clinicopathologic Study of 39 Cases in Comparison to Pancreatic Intraductal Papillary Mucinous Neoplasm (IPMN) in a Single North American Institution.

Hwajeong Lee, Flavio G Rocha, David S Klimstra, Gloria Q Young, William R Jarnagin, Nora Katabi. Memorial Sloan Kettering Cancer Center, New York, NY

Background: Biliary Intraductal Papillary Neoplasm (IPN) is the least common subtype of bile duct tumor. Despite controversies on nomenclature and classification, IPN is relatively well-documented in Asia and is considered analogous to pancreatic IPMN by some authors. Comparative studies of IPN with detailed clinical and histologic data are lacking in North American populations.
Design: We identified 39 cases of IPN (1993-2010) and randomly selected 44 cases of IPMN for comparison. Clinicopathologic features were analyzed in both cohorts and survival analysis was performed for IPN in relation to the pathologic parameters. Immunohistochemical (IHC) stains were performed on 33 IPNs.
Results: 39 IPNs were identified among 343 biliary carcinomas (11%), including 23 hilar, 4 intrahepatic and 12 distal bile duct primaries. Mean size was 4.5 cm. 1 case was associated with hepatolithiasis. 69% of IPNs were of pancreatobiliary (PB) type and the remainder were oncocytic (ONC, 15%), gastric (GAS, 10%) and intestinal (INT, 5%) types. All IPNs showed high grade dysplasia and had a predominant papillary architecture in 80%. Invasive carcinoma was present in 74% (90% tubular pattern, 10% colloid) and the invasive component was >10% of the tumor volume in 55%. The IPMNs were more commonly GAS (43%) and INT (29%) types. PB type comprised only 9% of IPMNs. High grade dysplasia and invasive carcinoma were less frequent in IPMNs, 57% and 20% respectively, and >30% of invasive carcinomas were colloid type. CK7 was pos in 88% of IPNs. INT (n=2) were pos for CK20 (2), CDX2 (2) and MUC2 (1). PB (n=23) were pos for MUC1 (22), MUC6 (11), and MUC5AC (6). ONC (n=5) were pos for MUC6 (4), MUC1 (3), MUC5AC (5), and HepPar1 (5). GAS (n=3) were pos for MUC1 (3), MUC5AC (2), and MUC6 (3). Expression of mesothelin, CEA, B72.3, and CA125 was not different between the epithelial types. The IHC profile of epithelial types in IPNs was similar to that reported for pancreatic IPMNs. The presence and depth of invasion (>5mm), margin status, and MUC1 immunolabeling were associated with worse median survival (p<0.05).
Conclusions: IPN in the North Americans appears to have no obvious risk factors. Although there is some morphologic overlap with pancreatic IPMNs, the majority of IPNs have a pancreatobiliary phenotype and are invasive at diagnosis, indicative of a distinct carcinogenesis and more aggressive behavior than IPMNs.
Category: Liver & Pancreas

Monday, February 28, 2011 1:30 PM

Platform Session: Section D, Monday Afternoon


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