Hyperplastic Polyp of the Gallbladder Mimicking a Shallow T2 Gallbladder Carcinoma: A Case Report

Ultrasonography has shown that many T2 gallbladder carcinomas (GBCs) demonstrate a deep hypoechoic area, and many shallow T2 GBCs show a conically thickened, outermost hyperechoic layer. However, this report describes a case of a hyperplastic polyp, of the gallbladder, with similar sonographic findings. This case reviews and analyzes the ultrasonographic imaging, as well as the pathologic correlation. Endoscopic ultrasound (EUS) revealed a thickened, outermost hyperechoic layer beneath a protruding lesion in the gallbladder fundus. The lesion was coupled with a deep hypoechoic area and a pancreaticobiliary maljunction (PBM). Pre-contrast computed tomogram (CT) demonstrated a soft tissue density mass in the fundus. Magnetic resonance imaging (MRI) disclosed no decreased-diffusion lesion under the diffusion-weighted image. Without any finding suggestive of an obvious advanced GBC, a full-thickness laparoscopic cholecystectomy was performed. The histopathology report indicated a hyperplastic polyp, which consisted of hypertrophic muscle, increased fibrosis, and a conically thickened subserosal fatty layer underneath the polyp. A specific benign protruded lesion may, though rarely, demonstrate similar EUS findings to those of shallow T2 carcinoma.