PAS inclusions, immunoreactive tenascin and proliferative activity in low-grade chondrosarcomas.

To distinguish between chondrosarcoma (grade 1--borderline histology) and enchondroma, we examined six chondrosarcomas (grade 1--borderline histology) which looked like benign lesions. Their diagnosis, albeit based on clinical, radiologic and pathologic examinations, was not easily reached. Moreover, we examined six enchondromas and 11 chondrosarcomas, the diagnoses of which were straightforward. All cartilaginous tumors were studied, placing emphasis on PAS-positive intracytoplasmic globules. Anti-Ki67 proliferation-associated nuclear antigen antibody and tenascin antibody were applied. The following features were observed in low-grade chondrosarcomas: (1) masses of hyalin and/or myxoid cartilage invading spaces around the tumor, (2) host lamellar bone trabeculae surrounded by cartilage on all sides, (3) tumoral resorption of bone trabeculae. Intracytopasmic hyalin globules (ICG) were more frequently found in malignant than in benign neoplasm (p = 0.042). Moreover, tenascin matrix immunoreactivity was more likely to be observed in benign than in malignant neoplasm (p = 0.029). Ki67 immunoreactivity was more frequent in characterized than in low-grade chondrosarcomas or in enchondromas, where it was null (p = 0.0044).