Amyloidosis of the gallbladder mimicking gallbladder cancer

We report a rare case of amyloidosis of the gallbladder in a 63-year-old woman with a history of primary amyloidosis. The patient was asymptomatic. Blood chemistry and hematologic laboratory levels, as well as values for tumor markers, were unremarkable. Ultrasonography (US) of the abdomen showed a focal echogenic lesion (22 x 15 mm) in the body of the gallbladder, and moderate enhancement was noted on contrast-enhanced US. Abdominal computed tomography revealed nodular wall thickening in the body of the gallbladder that was enhanced by contrast material. Although this patient was asymptomatic, the existence of gallbladder cancer could not be totally denied. Therefore, laparoscopic cholecystectomy was performed for total biopsy of the gallbladder. An intraoperative frozen-section examination revealed evidence of mild chronic cholecystitis with the appearance of hyalinal stroma. There was no malignant lesion. The final diagnosis, amyloidosis of the gallbladder, was obtained by alkaline alcoholic Congo red staining. Amyloid depositions were found in the walls of the vessels in the submucosa and the lamina propria mucosae, consistent with an elevated nodular lesion in the body of the gallbladder. To our knowledge, this is the first case of amyloidosis of the gallbladder mimicking gallbladder cancer that was diagnosed after laparoscopic cholecystectomy.