Question: A 40-year-old man with history of adenocarcinoma of sigmoid colon, pT3N1acM0, stage III, status post laparoscopic-assisted anterior resection with adjuvant chemotherapy 3 years ago, experienced intermittent right upper quadrant abdominal pain in recent months. Physical examination and laboratory study were unremarkable. Abdominal sonography showed a hyperechoic stricture at gallbladder body ( Figure A, arrow A) and focal wall thickening over gallbladder fundus ( Figure A, arrow B), 14 mm in thickness, with some anechoic cystic spaces, with gallstone at fundal part ( Figure A, arrow C). For the differential diagnosis, a magnetic resonance cholangiogram was performed.According to the images, what are the tentative diagnoses? Is surgical intervention indicated?See the Gastroenterology web site (www. gastrojournal.org) for more information on submitting your favorite image to Clinical Challenges and Images in GI.