<prompt> A patient with Ewings sarcoma. Histology shows small round cells. These cells are filled with which of the following -GlycogenIronFatMucin  <response>: Ewing sarcoma It is the second most bone sarcoma in children after osteogenic sarcoma.It is primary malignant small round cell tumor of bone.It is derived from primitive neuroectoderm.Age 10-15 years, Sex M FUsually arises in the diaphysisFemur Tibia 23rdFlat bones of pelvis 33rdImportant microscopic featuresScant cytoplasm in tumor cells which is clear because it is rich in glycogen.Homer - Wright rosettes.Important Radiological featuresOnion-skin periosteal reaction.Sun-rays appearance more common in osteogenic sarcoma.Codmans triangle It is also more common in osteogenic sarcoma. 