In an effort to investigate the utility of immunostaining for
S-100 protein in the differential diagnosis of
chondroblastoma, the expression of
S-100 protein in nine
chondroblastomas was compared with that in six
giant cell tumors, six
aneurysmal bone cysts, four giant cell reparative
granulomas, six cases of fibrous dysplasia, two cases of
osteitis fibrosa cystica, two nonossifying
fibromas, and one
clear cell chondrosarcoma. Five
enchondromas, three typical
chondrosarcomas, and one
mesenchymal chondrosarcoma were also included as control
tumors. The proliferating stromal cells in seven of the nine
chondroblastomas stained for
S-100 protein, as did the lacunar chondrocytes in all of the
enchondromas and
chondrosarcomas and rare stromal cells in the
clear cell chondrosarcoma. In contrast, none of the other tumefactive bone lesions included in this study demonstrated
S-100 protein immunoreactivity. These results suggest that immunohistochemical assessment of
S-100 protein may be a method for diagnostically separating
chondroblastoma from pathologic entities that could be histologically confused with it in the presence of limited biopsy material. However,
clear cell chondrosarcoma would appear to represent an exception to this general statement.