<prompt> Glycogen containing cells is feature ofEwings sarcomaChondromyxoid tumorChondroblastomaOsteosarcomas  <response>: Ans. a Ewings sarcoma. Ref. Robbin, Pathology, 6th ed., 1244EWINGS SARCOMA Ewings sarcoma constitutes -10-15 of all bone sarcomas Is common in adolescence peak incidence in the second decade of life. It typically involves the diaphyseal region of long bones, Also has an affinity for flat bones. X-ray: characteristic 6ionion peel periosteal reaction with a soft tissue mass better seen by MRI. The soft mass is composed of sheets of monotonous, small, round, blue cells and can be confused with lymphoma, embryonal rhabdomyosarcoma, and small-cell carcinoma. It is composed of sheets of uniform small, round cells that are larger than lymphocytes, rich in glycogen with Homer- Wright rosettes tumor cells with PAS positive Glycogen-filled cytoplasm characteristic. The presence of p3032, the product of the mic-2 gene which maps to the pseudoautosomal region of the X and Y chromosomes is a cell-surface marker for Ewings sarcoma and other members of PNETs. In approximately 85 of patients t 11;22 q24;ql2 translocation is seen. It is Undifferentiated--high grade tumor Ewings is always classed G4. It is very aggressive, and it is therefore considered a systemic disease. Common sites of metastases are lung, bones, and bone marrow. Ewings sarcoma can be curable, even in the presence of metastatic disease, especially in children 11 years. Systemic chemotherapy is the mainstay of therapy, often being used before surgery. Local treatment for this tumor includes surgical resection, usually with limb salvage or radiation therapy. More PNETs are known to arise in soft tissues; which include -- Peripheral neuroepithelioma,- Askins tumor chest wall, and- Esthesioneuroblastoma.Other small round cell tumors includeQ TumorClassic cytogenetic abnormality1.Wilms tumor11p13deletionmutation2.Lymphoblastic lymphoma ALLt 9;123.Rhabdomyosarcomat 2;13, llpdeletion4.Neuroblastomalpdeletion,N-myc amplification,DNA hyperploidy5.Medulloblastoma17q6.Retinoblastoma13q14deletionmutation7.Ependymoblastoma 8.Burkits lymphomat 11;229.Small cell carcinoma Note: Osteosarcoma is not a round cell tumor. 