Osteosarcoma: histological evaluation and grading

With 60 cases of osteosarcomas a histological evaluation from + to +++ carried out for mitoses, osteoid formation, presence of multinucleated giant cells, and tumor necrosis. A subclassification in osteoblastic, chondroblastic, and fibroblastic type of osteosarcoma (according to Dahlin) and a histological grading from + to +++ based on degree of cellular atypism was also done. In our material no relations between these three types of osteosarcoma and chance for survival became evident. There was, however, a significant correlation between grade of atypism and rate of mitoses. Grading of oestosarcomas from + to +++ showed that cases with grade III osteosarcoma remained only seldomly without metastases during the course of the disease. Grade I osteosarcomas and also grade II tumors showed a higher number of patients with 2-year survival. However, neither correlation between tumor grade and incidence of metastases, nor with chances for survival were statistically significant. Nevertheless, characterization of osteosarcomas, by a histological grading from + to +++ based on cellular atypism and mitotic count is advisable, in addition to the TNM stages. This histological grading appeared to be more practicable than subclassifications of osteosarcoma by type which had been tested by us in a previous study (Konrad et al., in press).