The classification of cartilaginous
neoplasms of the craniospinal axis is controversial. Indeed, the very existence of chondroid
chordomas has recently been questioned. In an effort to clarify the direction of differentiation of cartilaginous
neoplasms of this region, 17
neoplasms obtained from 17 patients with cartilaginous
tumors of the craniospinal axis were examined by immunohistochemistry with a panel of
antibodies. The panel included
antibodies to
cytokeratin (CK),
epithelial membrane antigen (EMA),
vimentin (VIM),
S-100 protein,
carcinoembryonic antigen (CEA), and
type II collagen. Areas with cartilaginous differentiation were present in all 17
neoplasms. These areas were characterized by a matrix of amorphous blue ground substance with lacunae that contained enlarged and slightly atypical cells. This cartilaginous matrix stained strongly for
type II collagen. Thirteen of the 17
neoplasms had a biphasic growth pattern in which areas with conventional
chordoma were admixed with areas with cartilaginous differentiation. The cells within the cartilaginous components of these 13
neoplasms stained for CK (10 of 12 cases), EMA (10 of 13 cases), VIM (12 of 12 cases),
S-100 protein (seven of 12 cases), and CEA (two of nine cases). Similarly, the conventional
chordoma components of these same 13
neoplasms stained for CK (12 of 12 cases), EMA (13 of 13 cases), VIM (12 of 12 cases),
S-100 protein (nine of 12 cases), and CEA (two of nine cases). The hyaline-appearing areas between the cords and sheets of cells of the conventional
chordoma components of these 13
tumors also stained with
type II collagen. These 13
tumors with both neoplastic cartilage and conventional
chordoma were classified as chondroid
chordomas. One of the 17 cases was composed entirely of neoplastic cartilage; however, the cells within the matrix of the cartilage of this
neoplasm stained with the epithelial markers (CK and EMA). Based on the presence of epithelial differentiation within this otherwise cartilaginous
neoplasm, it was also classified as a chondroid
chordoma. In contrast, the remaining three cases without histologic evidence of
chordoma differentiation did not
stain for CK or EMA, but they did
stain for
S-100 protein (three of three cases) and VIM (three of three cases). These three
tumors were therefore classified as
chondrosarcomas. For purposes of comparison, 19 conventional
chordomas without cartilage and 29 peripheral
chondrosarcomas were also stained. The 19 conventional
chordomas stained in a pattern similar to the conventional
chordoma components of the chondroid
chordomas, whereas the 29 peripheral
chondrosarcomas stained in a pattern similar to the three
chondrosarcomas of the craniospinal axis.(ABSTRACT TRUNCATED AT 400 WORDS)