Gallbladder Cholesterol Polyp Covered by Viscous Biliary Sludge, Mimicking T1a Carcinoma

A gallbladder polypoid lesion (GPL) identified on non-contrast computed tomography (CT) is typically reported as neoplastic, while a cholesterol polyp (CP) is generally non-visible on non-contrast CT. However, we encountered a GPL that histopathology confirmed as CP with a thick stalk, despite being visible on non-contrast CT. The visibility was attributed to the mucus-producing ability of the CP epithelium. Thus, a GPL seen on non-contrast CT does not necessarily indicate a neoplastic lesion. Surgical decisions should be made meticulously, based on ultrasound features such as a deep hypoechoic area, a conically thickened outermost hyperechoic layer, or changes in lesion size on contrast-enhanced ultrasound.