[391] Fine Needle Aspiration Cytology of Intraductal Papillary Mucinous Neoplasm of the Pancreas: A Study of 128 FNA Cases with Correlating Histopathology

TT Brown, SS Sikdar, RA Marks, NP Agaram, M Al-Haddad, JM DeWitt, X Wang, RE Emerson, CM Schmidt, HM Cramer. Indiana University School of Medicine, Indianapolis, IN

Background: Intraductal papillary mucinous neoplasm (IPMN) is considered to be a precursor lesion for some pancreatic adenocarcinomas. The preoperative cytologic evaluation of patients with suspected IPMN helps assist the clinician in therapeutic decision-making. In this study, we assess the accuracy of the FNA diagnosis of IPMN and refine our criteria for the cytologic diagnosis of this entity.
Design: A computerized search of our laboratory information system was performed for the 14-year period ending June 30, 2009 to identify all cytology and surgical pathology cases in which IPMN was diagnosed or considered in the differential diagnosis. All reports and all available FNA and surgical pathology slides were then retrospectively reviewed.
Results: Of 128 patients in whom both FNA and pancreatic resection were performed, a final histologic diagnosis of IPMN was rendered in 119 cases. For 40 of the 119 histologically confirmed IPMN cases (34%), the preoperative FNA diagnosis was IPMN. For the remaining 79 histologically confirmed IPMN cases (66%), the FNA diagnoses included: extracellular mucin (25 cases, 21%), benign lesions (22 cases, 18%), cyst/pseudocyst (3 cases, 2.5%), negative/contaminant/unsatisfactory (11 cases, 9%), atypical cells (4 cases, 3%), mucinous cystic neoplasm [MCN] (8 cases, 7%), IPMN or MCN (1 case, 1%), adenocarcinoma arising in an IPMN (1 case, 1%), mucinous adenocarcinoma (3 cases, 2.5%), and adenocarcinoma NOS (1 case, 1%). In 9 of the 128 cases, an FNA diagnosis of IPMN was rendered, but not confirmed by histology. The histologic diagnoses for those 9 cases included: benign lesions (3 cases, 33%), mucinous ductal ectasia (1 case, 11%), mucinous neoplasm (2 cases, 22%), adenocarcinoma (1 case, 11%), adenocarcinoma with PanIN (1 case, 11%), and PanIN (1 case, 11%).
Conclusions: In our series, the sensitivity of FNA for the diagnosis of IPMN was relatively low with only 40% of histologically proven cases having received an accurate preoperative FNA diagnosis of IPMN. Some of the IPMNs (7%) were misclassified as MCN by FNA, an error that may be preventable by more careful correlation with imaging findings. Of note, abundant extracellular mucin was detected in an additional 20% of cases, suggesting that the presence of extracellular mucin alone could constitute a cytologic diagnostic criterion for IPMN, when observed in conjunction with appropriate imaging findings.
Category: Cytopathology

Wednesday, March 24, 2010 1:00 PM

Poster Session VI # 41, Wednesday Afternoon


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