Effect of Preoperative Adjuvant Treatment on the Reactive Zone of Malignant Bone Tumors.

We observed microscopically the effects of preoperative adjuvant treatment on the reactive zone surrounding the neoplasmas in 14 cases of osteosarcoma, 3 cases of Ewing's sarcoma and 2 cases of MFH of bone. The reactive zone of biopsied specimens, which showed peritumoral edema and perivascular lymphocytic infiltration, was transformed into a thick membranous capsule in resected specimens after the treatment. The extramedullary component invading the periosteal soft tissues was completely covered with a thick membranous capsule. Invading foci within skeletal muscles were nearly covered with not a thick membranous capsule but a scar tissue mixed with striated muscle fibers. However, no capsular structures were seen around the intramedullary component.These findings might indicate that preoperative adjuvant treatment is of use to reduce the safety margin near the extramedullary component of the neoplasmas in the limb sparing surgery.