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
Zellballen pattern seen in: 
Select and explain. 
A. Carotid body tumor, B. Lymphoepithelial cyst, C. Cholesteatoma, D. Thyroglossal cyst
A: Carotid body tumor
Answer: A: Carotid body tumor 
Explanation: 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.