[Chemotherapy-induced changes in high grade central osteosarcomas-experiences gained through the assignment as reference-pathologists of the COSS-studies].

High-grade central osteosarcomas are the most frequent malignant bone neoplasms in childhood and adolescence. Their prognosis has been substantially improved using neoadjuvant chemotherapy. The morphological examination of surgical specimens reveals important information regarding the success of treatment. The histological determined degree of regression represents one of the most reliable therapy-related prognostical factor. Thus pathological analysis of the surgical specimens is of great importance notwithstanding the improved clinical and radiological diagnostic of osteosarcoma.