An extraskletal Ewing sarcoma in a nine year olds boy a case report

Introuduction: ewing sarcoma is the second most frequent primary malignant bone cancer following osteosarcoma. the predominant feature is densely packed small cells with round nuclei without prominent nuclei 1. the frequency of ewing sarcoma in the population younger than 20 years is approximately 2.9 per million2 and is slightly more common in males. among small blue round cell tumors, classical ewing sarcoma of the bone, extraskeletal ewing sarcoma, skin tumors of the thoracic wall and peripheral primitive neuroectodermal tumors, also known as peripheral neuroepithelioma, are highly aggressive , poorly differentiated neoplasms with unknown histogenesis. for this group, the unifying terms ewing family of tumors (eft) or ewing tumors (et) has been coined after molecular evidence was obtained for their shared immunologic and genetic traits, and are currently more frequently termed ewing sarcoma family of tumors (esft)l. although ewing sarcoma of the bone can break through the cortex and extends into the surrounding tissues, this tumor also occurs as a primary soft tissue neoplasm without bone involvement3. case description: we herein present the case of a nine-year-old male who developed a large pelvic mass and urinary retention with right leg edema due to extraskeletal ewing sarcoma. discussion: in our case, cd99 (mic2) was strongly positive and vimentin also was positive, but desmin and nse were negative. after two courses of ewing sarcoma chemotherapy, the edema of the right leg and scrotal swelling improved and tumor mass was dramatically reduced.