[456] Utility of Immunostains in Differentiating Gastric-Type Pancreatic Intraductal Papillary Mucinous Neoplasms (G-IPMNs) from Gastric and Duodenal Mucosal Contaminants in Pancreatic Endoscopic Ultrasound-Guided Fine Needle Aspirates.

Linjun Xie, Stefan Pambuccian, Stuart E Cameron, Steven Debol, Evin H Gulbahce, Anthony Rizzardi, Rachel Isaksson Vogel, Stephen C Schmechel. University of Minnesota, Minneapolis

Background: Due to their frequency and potential curability, IPMNs are a major target of pancreatic EUS-FNA. Their cytologic diagnosis may be difficult due to lack of cytologic atypia and resemblance to normal gastric (GM) or duodenal (DM) mucosal fragments, which are often contaminants of transgastric or transduodenal EUS-FNA. This study aimed to determine if immunohistochemical (IHC) stains may be useful to differentiate gastric-type IPMN (G-IPMN) from GM and DM.
Design: Tissue microarrays (TMAs) were constructed from 19 cases of resected G-IPMN, 20 GM, 20 DM and 20 benign pancreatic tissues. IHC stains AMACR (P504S), B72.3, CDX2, CK7, CK20, HepPar1, mCEA, MOC31, MUC1, p16 and villin were applied to TMA sections. The extent and intensity of staining were assessed on a 0-3+ scale for all stains, and digitized IHC staining intensity was determined for selected stains.

 Gastric mucosa (n=20)Benign pancreatic tissue (n=20)Duodenal mucosa (n=20)IPMN Gastric type (n=19)
AMACR (P504s)80% )90%100%89%
HepPar15% F0100%32%
MUC188% (n=16)91% (n=11)0 (n=9)30% (n=10)
P165% F95% F089%

P16 showed the best discrimination of GM from GT-IPMN: p16 stained nuclei and cytoplasm in 17 of 19 G-IPMN cases (89%), while only one GM with intestinal metaplasia was focally p16 positive. Other useful markers included villin, which showed a predominantly brush border pattern in G-IPMN (63%) versus a mixed brush-border/cytoplasmic pattern in 45% of GM, and 3.3-fold higher expression in DM versus G-IPMN (p<0.0001); and mCEA, which was diffusely positive in all G-IPMN but only weakly positive in 65% of GM, and 3.4-fold higher expression in G-IPMN than DM (p=0.003). Markers of limited utility included HepPar-1, which stained all DM samples but only 1 of 20 GM samples and 32% of G-IPMNs; and B72.3, which stained 77% of G-IPMNs and 40% of GM.
Conclusions: Our results indicate that p16, villin and mCEA may be useful in distinguishing G-IPMN from GM and DM contaminants in cell block sections from pancreatic EUS-FNA.
Category: Cytopathology

Tuesday, March 1, 2011 9:30 AM

Poster Session III # 59, Tuesday Morning


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