High-grade osteoblastic osteosarcoma of the tibia. The tumor involves metaphysis and proximal diaphysis and infiltrates into the soft tissues. Note the sparing of the epiphysis. This is a post-chemotherapy specimen which showed 40% viable tumor. Before the advent of chemotherapy, the 5-yr survival for osteosarcoma was around 20%. With modern chemotherapeutic regimens, long-term survival is seen in about 75% of patients. Chemotherapy has also allowed greater use of limb-sparing procedures. Most specimens handled by surgical pathologists these days have been altered by preoperative chemotherapy. The degree of tumor necrosis induced by chemotherapy is an important prognostic indicator and pathologists are expected to assess this feature when evaluating specimens. Image copyright: pathorama.ch; Used with permission.