Histological grading and morphometric analysis of cartilaginous tumours.

Morphometric analysis of cartilaginous tumours was performed on 25 chondrosarcomas, 9 cases of enchondroma (ENCH), and 2 chondroblastic osteosarcomas (CBOS). The chondrosarcomas were classified into three grades of malignancy according to Evans' histological classification and were further divided into low and high grades of malignancy. Cellularity, nuclear area, binucleate cells and mitotic figures were examined using formalin-fixed and paraffin-embedded specimens. The cellularity was significantly higher in high-grade chondrosarcoma (HGCS) than in low-grade chondrosarcoma (LGCS) (P less than 0.005). The nuclear area was larger in more malignant lesions. Significant differences in the nuclear area were found between ENCH and LGCS (P less than 0.005) and between LGCS and HGCS (P less than 0.01). Binucleate cells were found more frequently in LGCS than in ENCH (P less than 0.005). Although a few mitotic figures were found in HGCS, they were extremely rare in chondrosarcomas. Mitotic figures, however, were easily found in CBOS when compared with HGCS (P less than 0.05). These results suggest that nuclear area and binucleate cells are useful for differentiation between benign and malignant cartilaginous lesions and that easily detectable mitotic figures are a reliable marker for neoplastic cartilage in osteosarcoma.