This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrine, Subject name: Pathology
Zellballen pattern is found in histology of which of the following condition? 
Select and explain. 
A. Neuroblastoma, B. Paraganglioma, C. Ewings Sarcoma, D. RCC
B: Paraganglioma
Answer: B: Paraganglioma 
Explanation: Ans. (b) Paraganglioma(Ref: Robbins 9/1135)The histologic pattern in pheochromocytoma shows tumor cells composed of clusters of polygonal to spindle shaped chromaffin cells or chief cells that are surrounded by supporting sustentacular cells, creating small nests or alveoli called zellballen. These are supplied by a rich vascular network