This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Radiology
[{'content': 'On abdominal ultrasound gall bladder shows at neck and comet tail aifacts. The most likely diagnosis will be: \nSelect and explain. \nA. Adenomyomatosis, B. Adenocarcinoma of gall bladder, C. Xanthogranulomatous cholecystitis, D. Chelesterol crystals', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Adenomyomatosis Repeat from May 11 Adenomyomatosis is a benign condition characterized by hyperplastic changes of unknown etiology involving the gallbladder wall. It causes overgrowth of the mucosa, thickening of the muscular wall, and formation of intramural diveicula or sinus tracts termed as Reokitansky-Aschoff sinuses. These sinuses may contain cholesterol crystals. The presence of cholesterol crystals in theses sinuses can result in "ring down", "V-shaped",or "comet-tail" aifacts. The disease can be focal or diffuse. It has no malignant potential.', 'role': 'assistant'}]