This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: DNB 2018, Subject name: Pathology
[{'content': 'Zellballen pattern seen in: \nSelect and explain. \nA. Carotid body tumor, B. Lymphoepithelial cyst, C. Cholesteatoma, D. Thyroglossal cyst', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Zellballen pattern: Contain nest of sustentacular cells & chief cells with pale eosinophilc staining Seen in tumors of chromaffin cells, i.e pheochromocytoma & Paraganglioma (carotid body tumor). Most common location of these tumors is within adrenal medulla,where they give rise to pheochromocytomas & approximately 70% of extra-adrenal paragangliomas occur in head & neck region.', 'role': 'assistant'}]