Complete pathological response of pelvic Ewing sarcoma in adult female—a case report

Background: Ewing sarcoma is a highly aggressive tumor that typically affects children and young adolescents. Around 87% of Ewing sarcoma are osseous tumors. However, there is a portion of these tumors that arise from soft tissue, otherwise known as extraosseous Ewing sarcoma (EES). Commonly affected places include the bones of the leg, pelvis, upper extremities axial skeleton, and ribs. Pelvic Ewing sarcoma is unique in that patients tend to experience higher rates of relapse, are more complex to surgically remove, and have lower disease-free and overall survival rates when compared to Ewing sarcoma in other locations. Ewing sarcoma tends to be a disease of childhood that is rarely seen in adults. When adults are impacted, survival rates are significantly lower than the survival rates of children. This case describes a complete pathologic response obtained after neoadjuvant chemotherapy in an adult female with pelvic Ewing sarcoma.