Pancreatic cyst aspiration analysis for cystic neoplasms: mucin or carcinoembryonic antigen--which is better?

Background: Differentiation between the various pathologies presenting as a cystic pancreatic lesion is clinically important but often challenging. We have previously advocated the performance of endoscopic ultrasound (EUS) with aspiration and determination of mucin and carcinoembryonic antigen (CEA) content. We sought to report the results of this ongoing protocol and determine the relative importance of cyst fluid mucin and CEA for the diagnostic process.

Methods: The institutions prospectively maintained pancreatic cyst database was accessed to identify patients who had undergone pancreatic EUS and cyst aspiration as part of their evaluation. Only those patients who had subsequently undergone resection were selected, with histopathology being the gold standard for comparison.

Results: From January 2000 to July 2009, 174 patients with pancreatic cystic disease underwent surgery, 121 of whom had an EUS with aspiration attempted at our institution with specimens sent for mucin and CEA. Based on histopathology, 86 mucinous lesions were identified, including 44 cystadenomas, 34 intraductal papillary mucinous neoplasms, 7 mucinous adenocarcinomas, and 1 intraductal oncocytic papillary neoplasm; 42 were nonmucinous lesions. The median cyst CEA levels were significantly higher in the mucinous lesions group at 850 versus 2 ng/mL (P = .001). The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), positive diagnostic likelihood ratio, and negative diagnostic likelihood ratio (NDLR) were calculated respectively for mucin alone (0.80, 0.40, 0.61, 0.63, 1.33, 0.68); CEA alone (0.93, 0.43, 0.51, 0.91, 1.63, 0.16); cytology alone (0.38, 0.9, 0.92, 0.31, 3.67, 0.69); mucin or CEA (0.83, 0.65, 0.87, 0.57, 2.51, 0.26); mucin or CEA or cytology (0.92, 0.52, 0.86, 0.68, 1.91, 0.15); mucin plus CEA (0.96, 0.34, 0.25, 0.97, 1.45, 0.12); mucin plus cytology (0.25, 0.97, 0.96, 0.29,7.25, 0.78); CEA plus cytology (0.12, 1.00, 1.00, 0.26, ∞, 0.88); and mucin plus CEA plus cytology (0.08, 1.00, 1.00, 0.25, ∞, 0.92).

Conclusion: Assessment of cyst mucin and CEA are complementary, with the best profile obtained when both markers are determined along with cytology. This combination provides a good sensitivity, PPV, and NDLR, as well as reasonable PPV and PDNR.