Chondroid Chordoma:A Hyalinized Chordoma Without Cartilaginous Differentiation

Abstract

"Chondroid chordoma" is a controversial and confusing entity that was originally described by Heffelfinger and colleagues as a biphasic malignant neoplasm possessing elements of both chordoma and cartilaginous tissue. Because the premise for this distinction was based strictly on histomorphologic criteria, the light microscopic, immunohistochemical, and electron microscopic features of the chondroid and chordoid areas of five chondroid chordomas of the skull base were evaluated separately, and compared to five typical chordomas and six low grade chondrosarcomas. Using light microscopy, chondroid chordoma revealed areas that resembled typical chordoma (chordoid areas) and areas that resembled low grade chondrosarcoma (chondroid areas). However, both the chordoid and chondroid areas had an epithelial phenotype and stained strongly for cytokeratin and EMA as well as S-100. 5'-nucleotidase, an enzyme that has been described in chordoma but not in chondrosarcoma, was found in both the chordoid and chondroid areas of one chondroid chordoma. Electron microscopic studies of both the chordoid and chondroid areas in four of the tumors demonstrated both tonofibrils and desmosomes. Chordoma demonstrated immunohistochemical and electron microscopic features that were nearly identical to chondroid chordoma. Chordoma was cytokeratin, EMA, S-100, and 5'-nucleotidase positive. Ultrastructurally, chordoma exhibited variably-sized vacuoles, abundant rough endoplasmic reticulum (RER), and desmosomes with tonofilaments. In contrast to chondroid chordoma, chondrosarcoma consistently stained for only S-100 protein and was cytokeratin, EMA and 5'-nucleotidase negative. Ultrastructurally, chondrosarcoma demonstrated a flocculogranular matrix, glycogen, abundant RER, and scalloped cellular outlines, but lacked desmosomes with tonofilaments. These findings indicate that "chondroid chordoma" is a variant of chordoma with histologic features that may mimic chondrosarcoma. Despite the resemblance of these hyalinized areas to cartilaginous tissue, these tumors retain their epithelial phenotype. Biphasic differentiation is not present. These findings undermine the original premise for distinguishing "chondroid chordoma" from typical chordoma. The authors propose that these tumors be classified as "hyalinized chordomas," rather than "chondroid chordoma," to clarify their histogenesis and avoid confusion with chondrosarcomas of the base of the skull.

Chondroid chordoma of the L5 spinous process and lamina: a case report

“…Chondrosarcomas are characteristically cytokeratin and epithelial membrane antigen negative. Both typical chordoma and chondrosarcoma stain positive for S-100 [12]. Our case stained positively for S-100.…”

The ultrastructural aspects of neoplastic myoepithelial cell in pleomorphic adenomas of salivary glands

“…Although the epithelial-mesenchymal transdifferentiation process was considered normal only in the fetal period, in the process of palate, neural crest, metanephric and cardiac development, they may also take place after birth [57]. Thus, such process may be observed in teratocarcinomas, mesotheliomas, carcinomas with (pseudo) sarcomatous differentiation and chordomas of the spinal axis [58][59].…”

Chondroid Chordoma of the Lateral Skull Base

“…CC occurs almost exclusively in the spheno-occipital region, while classical chordoma arises mainly in sacrococcygeal areas [1,2,9,11]. Embryonic notochord remnants at these sites may often be trapped in the bone and sometimes fail to degenerate, undergoing neoplastic changes instead until they form chordoid tumors [12,13].…”

“…They account for less than 1% of all intracranial neoplasms [1][2][3], the clivus and spheno-occipital synchondrosis being their most common site of origin; only few cases presenting at the lateral skull base have been reported [4][5][6]. Chondroid chordoma (CC) is a controversial clinicopathological entity, first described by Falconer et al [7] in 1968 as a biphasic neoplasm composed of cartilaginous and chordoid elements in variable amounts.…”

“…Several years later, Heffelfinger et al [1] and Richter et al [8] further documented its clinical and morphological features. This neoplasm is a relatively uncommon variant of chordoma, approximately accounting for less than a third of all chordomas occurring at the skull base [1,2,9], and is characterized by a more indolent clinical course than conventional chordoma [9].…”