Chondroid
tumors comprise a heterogenous group of benign to overt
malignant neoplasms, which may be difficult to differentiate from one another by histological examination. A group of 43 such
tumors was stained with nine relevant
antibodies in an attempt to find consistent marker profile(s) for the different subgroups. Archival material from three extraskeletal myxoid
chondrosarcomas, five
chordomas, five chondromyxoid
fibromas, five
chondroblastomas and 25
chondrosarcomas was stained with
antibodies against
osteonectin, bcl-2, cox-2, actin,
calponin, D2-40 (podoplanin), mdm-2, CD117 (c-kit) and YKL-40. All 25
chondrosarcomas showed a positive staining reaction for D2-40, none for actin and CD117, and a partial reactivity for bcl-2 (36%).
Chondroblastomas (5/5) and chondromyxoid
fibromas (2/5) were the only
tumors with a positive reaction for actin, and all
chondroblastomas (n=5) and extraskeletal myxoid
chondrosarcomas (n=3) were positive for bcl-2. In contrast to all other
tumors, two of three extraskeletal myxoid
chondrosarcomas were also positive for CD17 and negative for
osteonectin, cox-2, mdm-2 and actin. All five
chordomas were negative for D2-40 and positive for mdm-2 and YKL-40. The diagnosis of
chondrosarcoma may be aided by its positivity for D2-40 and YKL-40 and its lack of reactivity for actin and CD117. This should be seen in the light of no reaction for D2-40 in
chordomas and a corresponding lack of reaction for
osteonectin, cox-2, mdm-2 and actin in extraskeletal myxoid
chondrosarcomas. A convincing immunoreactivity for
calponin and/or actin in chondromyxoid
fibromas and
chondroblastomas may also be helpful in differentiating these
tumors from
chondrosarcomas.