Utility of EUS-FNA and Cyst Fluid Analysis in the Diagnosis of Intraductal Papillary Mucinous Tumors: Correlation with Histopathology in 74 Patients Shireen A. Pais, Siriboon Attasaranya, Julia Leblanc, Stuart Sherman, Lee Mchenry, Max Schmidt, John Dewitt Background: Intraductal papillary mucinous neoplasms (IPMNs) of the pancreas are precancerous cystic tumors characterized by dilation of the main pancreatic duct (IPMN-M) alone, side branches alone (IPMN-Br) or both. The aim of this study is to evaluate the accuracy of EUS-FNA and cyst fluid analysis in the diagnosis of IPMNs. Methods: Databases at our hospital from 7/96-11/05 were used to retrospectively identify patients who underwent EUS followed by surgery for IPMNs. EUS was performed by 7 experienced endosonographers with on-site cytopathologists. Surgical pathology was the diagnostic gold standard. The following were classified as benign: IPMN adenoma, low grade, borderline or highgrade dysplasia. Only invasive carcinoma was considered as malignant. Results: 74 patients (38M; mean age: 65 G 10 yrs) were identified with 21 (28%) malignant and 53 (72%) benign IPMNs. Tumor locations: pancreatic head alone, body alone, tail alone or multifocal in 39 (53%), 17 (23%), 5 (6%) and 9 (12%) respectively. The tumors were classified as IPMN-M, IPMN-Br or both in 21 (28%), 18 (25%) and 35 (47%) respectively. Only one patient had high-grade dysplasia (1.3%). EUS-FNA (mean 3.4 passes; range: 1-8) was performed in 65 (88%). Compared to surgical pathology, the sensitivity, specificity, PPV, NPV, and accuracy of EUS-FNA for the diagnosis of malignancy were 75%, 91%, 79%, 89% and 86% respectively. There was no significant difference in the mean number of passes performed between malignant (3.7 G 2.3) and benign (3.4 G 2.0) tumors respectively (p Z 0.42). Cyst fluid CEA and CA 19-9 were available in 8 and 5 patients in the malignant group and 15 and 4 patients in the benign group respectively. There was no statistically significant difference between the mean CEA in the malignant IPMNs (1769.8 ng/ml G 4159.9; range: 2.5 to 12765) compared to the benign tumors (511 ng/ml G 1192.5; range 0.5-4878; p Z 0.28) or the mean CA 19-9 in the malignant IPMNs (2973.2 U/ml G 14651; range: 29.4-40490) compared to the benign tumors (16390 U/ml G 4218; range: 15-10236; p Z 0.08). If a CEA of 1000 ng/ml is used as the arbitrary cutoff between benign and malignant, CEA has sensitivity, specificity, PPV, NPV and accuracy of 38%, 60%, 33%, 64% and 52% respectively. Similarly, a CA 19-9 cutoff of 10,000 U/mL has a sensitivity, specificity, PPV, NPV and accuracy of 80%, 50%, 67%, 67% and 67% respectively for differentiating benign from malignant IPMNs. Conclusions: The sensitivity, specificity and accuracy of EUS-FNA for the diagnosis of malignancy in IPMN were 75%, 91% and 86% respectively. Tumor markers are only moderately accurate in differentiating malignant from benign IPMNs.