EXPRESSION OF METALLOPROTEINASES AND TISSUE INHIBITOR IN CARTILAGINOUS NEOPLASMS OF BONE

Difficulties may be encountered when attempting to histologically diff erentiate a low-grade chondrosarcoma from the benign enchondroma. Beca use many malignant neoplasms demonstrate an imbalance between metallop roteinases and tissue inhibitors of metalloproteinases, we compared th e expression of these markers in benign enchondromas and chondrosarcom as of bone. Eight enchondromas and 11 chondrosarcomas of the long bone s (six grade 1, two grade 2, and three grade 3) were collected from th e files of the Department of Pathology at the Hospital for Joint Disea ses. Immunohistochemistry was performed on paraffin-embedded tissue us ing antibodies to metalloproteinases (MMP-1, MMP-2, MMP-9) and a tissu e inhibitor of MMP (TIMP-1). Both enchondromas and chondrosarcomas sho wed cytoplasmic immunoreactivity for MMP-1 and MMP-2 in the neoplastic chondroid cells. Furthermore, when the extracellular matrix was evalu ated, nine chondrosarcomas demonstrated matrix staining for MMP-1 as d id eight chondrosarcomas for MMP-2. However, none of the eight enchond romas showed matrix reactivity for MMP-1 or MMP-2. Six enchondromas an d 10 chondrosarcomas showed cytoplasmic positivity for MMP-9. Matrix s taining for MMP-9 was observed in two enchondromas and six chondrosarc omas. Cytoplasmic staining for TIMP-1 was present in all cases. Matrix staining for TIMP-1 was seen in seven chondrosarcomas and one enchond roma. The expression of metalloproteinases and tissue inhibitors of me talloproteinases may have a role in influencing the behavior of chondr oid neoplasms. However, the presence of MMP-1, MMP-2, and TIMP-1 in th e extracellular matrix of chondrosarcomas and the increased expression of MMP-9 in chondrosarcoma as compared with enchondroma suggest abnor mal regulation in their expression and may be useful markers in distin guishing benign from malignant chondroid lesions.