Ultrasonographic Features of Nonneoplastic Protrusions in Pancreatic Cysts by Contrast-Enhanced Endoscopic Ultrasound

Abstract

Objectives Most of the pancreatic cyst protrusions detected by B-mode endoscopic ultrasound (BM-EUS) are nonneoplastic and are not enhanced by contrast-enhanced EUS (CE-EUS) using ultrasound contrast agent (USCA). This study aimed to identify useful findings for distinguishing between neoplastic and nonneoplastic pancreatic cyst protrusions on BM-EUS to facilitate efficient USCA use. Materials and Methods A total of 151 pancreatic cyst protrusions in 119 consecutive patients who underwent CE-EUS were analyzed. We focused on the echo level (hyperechoic/isoechoic/hypoechoic/anechoic), base type (sessile without a basal waist/sessile with a basal waist/pedunculated), surface type (smooth/irregular), and the presence/absence of a hyperechoic surface layer. Enhanced and unenhanced protrusions on CE-EUS were interpreted as neoplastic and nonneoplastic, respectively. Results Forty-five and 106 protrusions were enhanced and unenhanced, respectively, on CE-EUS performed using USCA. In univariable analysis of predictors of nonneoplastic protrusion on BM-EUS, the following factors were found to be significant: echo level (hypoechoic/anechoic), base type (sessile with a basal waist/pedunculated), a smooth surface, and a hyperechoic surface layer. Of these, only a hyperechoic surface layer remained significant in the multivariable analysis (P < 0.0001; odds ratio, 40.74; 95% confidence interval, 7.07–387.49). Conclusions Pancreatic cyst protrusions with a hyperechoic surface layer on BM-EUS are suggestive of nonneoplastic disease.