MIC-2 mutation associated with

Reference Robbins page no 613Ewing 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, the dis- tinction is not clinically significant. Ewing sarcoma family tumors account for approxi- mately 6% to 10% of primary malignant bone tumors and follow osteosarcoma as the second most common group of bone sarcomas in children. Of all bone sarcomas, ESFT have the youngest average age at presentation, since approximately 80% are younger than 20 years. Boys are affected slightly more frequently than girls, and there is a striking predilection for whites; blacks and Asians are rarely afflicted. ESFT usually arise in the diaphysis of long tubular bones, especially the femur and the flat bones of the pelvis. They present as painful enlarging masses,