Clear cell chondrosarcoma: a pathological and immunohistochemical study

Clear cell chondrosarcoma (CCC) is a rare malignant cartilaginous neoplasm of bone. CCC is characterized by clear cells (CCC cells), osteoclasts and osteoblasts. Many important questions concerning the varied histological features of CCC, and the interactions between CCC cells and coexisting osteoclasts and osteoblasts have not been fully investigated and remain controversial. The aim of this study is to clarify and explain the varied histological features and the possible interaction between tumour cells (CCC cells) and stromal cells such as osteoclasts and osteoblasts.

Four cases of CCC were histologically and immunohistochemically studied in order to elucidate the biological nature and histological characteristics. A comparative study with chondroblastoma and grade I conventional chondrosarcoma (CC) was also performed. S100 protein and type II collagen were expressed in CCC cells, chondroblastoma cells and CC cells. CD68 and matrix metalloproteinase-9 were expressed in coexisting histiocytes and osteoclasts. Parathyroid hormone-like protein (PTH-LP) was expressed in histiocytes, osteoclasts, osteoblasts, chondroblastoma cells and CCC cells. Platelet-derived growth factor (PDGF) and its receptor (PDGF-R) were observed in osteoblasts, chondroblastoma cells and CCC cells. However, PTH-LP, PDGF and PDGF-R were not expressed in CC cells. PCNA (proliferating-cell nuclear antigen) was expressed more intensely in CCC than in chondroblastoma.

These observations suggest that CCC cells trigger the varied histological changes in association with several cytokines. The difference of PCNA expression between CCC and chondroblastoma seemed to be related to the biological difference between the two tumours.