What is done in surgical excision of primitive bone tumors?

➢ On the surgical excision of a primary tumor, the pathologist must confirm the histological nature of the lesion, and specify, other characteristics of the tumor: o Extension of invasion (soft parts, joint) o Quality of the excision with histological margins. o If neoadjuvant CT: also assess the response of the tumor to chemotherapy by quantifying tumor necrosis. o In both cases of osteosarcoma and Ewing's sarcoma, a patient is considered a good responder if the tumor necrosis is greater than or equal to 90%