This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Gallbladder Cancer, Subject name: Surgery
[{'content': 'Precancerous lesion of gall bladder is \nSelect and explain. \nA. Porcelain gall bladder, B. Mirrizi syndrome, C. Cholesterosis, D. Acalculous Cholecystitis', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans is \'a\' ie Porcelain gall bladder "The calcified porcelain\' gallbladder is associated with more than a 20% incidence of gallbladder carcinoma. These gallbladders should be removed, even if the patients are asymptomatic" - Schwartz SurgeryMirizzi SyndromeBiliary obstruction may occur in cases of acute cholecystitis, as a result of external compression of the CBD by a large stone impacted in the Hartman pouch and the associated intense pericholecystic inflammatory process; this is termed Mirizzi Syndrome. (Washington Manual of Surgery, 4/e, p 310)', 'role': 'assistant'}]