Reflections on notochordal differentiation arising from a study of chordomas

Abstract

This study of thirteen cases of chordoma serves to emphasize the occurrence of three different histological patterns; classical, seven; chondroid, three; and intermediate or mesenchymal, three. The study also suggests that more adequate sampling of these tumours detects the chondroid variant more readily. These varying patterns of differentiation in tumours of notochordal origin suggest that the parent tissue may have the potential to develop along similar lines in the embryo. Thus mesenchymal and cartilaginous tissue formed from notochordal cells could contribute to the formation of the nucleus pulposus and inner portion of the intervertebral disc cartilages. This concept contrasts with the previously held view that the notochord atrophies at an early stage in embryonic development.

Chondroid Chordoma of the Lateral Skull Base

“…Similar immunohistochemical findings have been observed in several studies [2,4,9,[11][12][13]. Jeffrey et al [2] consequently consider that CC should be classified as chordoma with hyalinized stroma, because the tumor fails to show a true biphasic differentiation: both chondroid and chordoid areas express the epithelial immunophenotype.…”

“…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]. Indeed, notochordal remnants are generally found protruding through tiny defects of the basisphenoid region in 2% of autopsies [14].…”

Chordomas in Fischer 344 Rats

“…8,20 In humans, residual notochord has been identified in the nucleus pulposus of the intervertebral discs, peripheral zones of vertebral bodies, including the sacrum, and the spheno-occipital region of the sku1L2J0 Chordomas may arise anywhere along the vertebral column, but most commonly involve the cranial and caudal limits of the axial skeleton. The approximate distributions of chordomas in humans are: sacrococcygeal, 50%; vertebral, 15%; and sphenoid region of the cranium, 35%.19 Chordomas have been reported in human^,^.^ r a t~,~~J~J~ mice, 5 dogs,24 and mink.7 Chordomas in humans are highly infiltrative, grow slowly, produce bone destruction, and frequently extend into soft tissue.…”

Chordoma of the Thoracic Spine. Case Report.

“…28) Chordoma is composed of mostly epithelial, with less well-developed mesothelial features. 16,25) Positive staining of epithelial components (physaliphorous cells 8,31,34) ) for cytokeratin (Cam 5.2) and EMA are helpful in the differentiation from chondrosarcoma. 5,9,14) Positive staining of mesenchymal elements for S-100 protein, vimentin, NSE, and fibronectin differentiate chordoma from mucusproducing carcinomas.…”