This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Neck, Subject name: Surgery
[{'content': 'All of the following are true about chemodectoma except: \nSelect and explain. \nA. Firm, rubbery, pulsatile mass, mobile from side to side, B. Schamblin classification is used, C. Biopsy is diagnostic, D. Lyre sign is splaying of internal & external carotid aeries on angiography', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Carotid body tumor AKA Chemodectoma Commonly found in people living at high altitudes - because of chronic hypoxia -carotid body hyperplasia. Firm, rubbery, pulsatile mass, mobile from side to side - arises from medial side of carotid body or carotid bifurcation Diagnosis: Angiography shows Lyre sign - splaying of internal & external carotid aeries It is a vascular tumor - so, FNAC & biopsy are contraindicated Schamblin classification is used for carotid body tumor', 'role': 'assistant'}]