Chordomas: a histological and immunohistochemical study of cases with and without recurrent tumors.Clin Neuropathol. 2004 Nov-Dec;23(6):277-85.

Chordomas are rare, slow-growing and often recurrent neoplasms being composed of various cell types (physaliferous, epitheloid, chondroid), thus, showing a wide range of histological features. To study the relationship between histological and immunohistochemical pattern and biological behavior according to different cell types, the authors studied 33 specimens of 17 patients with and without recurrent tumors. Additionally, the histological features according to nuclear atypia and mitotic activity of both groups were analyzed and compared with each other. Predominance of one cell type was observed in 19 specimens (10 were composed mainly of physaliferous, 8 of the epitheloid and one of chondroid cell type). In 7 cases, areas of chondroid differentiation were present. MIB proliferation index tended not to be higher in recurrent tumors but in cases with nuclear atypia and nuclear pleomorphism seems to be predictive for recurrency. Immunohistochemically, nearly all cell types (physaliferous, epithelial-like and cells of chondroid differentiation) of both recurrent and non recurrent chordomas stained positive for epithel membrane antigen (EMA), cytokeratins (KL1, AE1/AE3), S100, vimentin and negative for HMB45 and desmin. Positive staining for NSE was observed in 70% of cases, however, the chondroid componente stained negative in every case.

Chondroid chordoma--a variant of chordoma. A morphologic and immunohistochemical study.Am J Clin Pathol. 1994 Jan;101(1):36-41.

In 1973, Heffelfinger and coworkers described a variant of chordoma that contained cartilaginous areas indistinguishable from hyaline type chondrosarcoma. They designated these tumors chondroid chordomas and found that they had a better prognosis than classic (nonchondroid) chordomas. Since that time, there has been an ongoing debate over whether chondroid chordoma is best considered a distinct clinicopathologic entity separable from chondrosarcoma or a misdiagnosed chondrosarcoma whose concept developed from the erroneous interpretation of morphology. In an attempt to clarify the issue, the authors used light microscopy and immunohistochemistry to study 12 chondroid chordomas, 38 classic chordomas, and 28 chondrosarcomas that arose in the base of the skull or spine. As a reference, they also analyzed the immunohistochemical profile of fetal notochord, ecchordosis physaliphora, and fetal hyaline cartilage. They found that all chondroid and nonchondroid chordomas were positive for cytokeratin, and the majority were also positive for epithelial membrane antigen (EMA) and carcinoembryonic antigen (CEA). In contrast, none of the chondrosarcomas stained for cytokeratin, EMA or CEA. Vimentin and S-100 were positive in more than 95% of both classic and chondroid chordomas and chondrosarcomas. The immunohistochemical profile of these tumors was similar to the pattern of immunoreactivity of their nonneoplastic counterparts. The authors conclude that chondroid chordomas is a variant of chordoma and should not be confused with chondrosarcoma. Because chondroid chordomas have been reported to have a better prognosis, they felt that this nosologic term should be preserved and that chondroid chordoma should continue to be a focus of clinical and pathologic study.