This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Musculoskeletal system, Subject name: Anatomy
Large intracytoplasmic glycogen storage is seen in which malignancy 
Select and explain. 
A. Osteosarcoma, B. Mesenchymal chondrosarcoma, C. Ewings sarcoma, D. Leiomyosarcoma
C: Ewings sarcoma
Answer: C: Ewings sarcoma 
Explanation: Refer Robbins page no 8th edition 1232Ewing sarcoma is a malignant bone tumor characterized by primitive round cells without obvious differentiation. Recently, Ewing sarcoma and primitive neuroectodermal tumor (PNET) have been unified into a single category: the Ewing sarcoma family tumors (ESFT) based on shared clinical, morphologic, biochemical and molecular features (discussed later). Although PNET demonstrates more neu- roectodermal differentiation than Ewing sarcoma