A patient with Ewing's sarcoma. Histology shows small round cells. These cells are filled with which of the following -

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 > F Usually arises in the diaphysis Femur & Tibia → 2/3rd Flat bones of pelvis → 3/3rd Important microscopic features Scant cytoplasm in tumor cells which is clear because it is rich in glycogen. Homer - Wright rosettes. Important Radiological features Onion-skin periosteal reaction. Sun-rays appearance (more common in osteogenic sarcoma). Codman's triangle (It is also more common in osteogenic sarcoma).