Neovascularization of nucleus pulposus: A diagnostic feature of intervertebral disc prolapse

Study Design. Seventy-five surgically excised prolapsed intervertebral discs were histopathologically evaluated. Fifteen prospective normal cadaveric discs were used as control specimens. Objective. To compare the morphologic features between the prolapsed and normal discs. Summary of Background Data. The histologic criteria were edge neovascularization of the fibrocartilage, chondrocyte cloning, fibrillation with fraying, and granular change. Methods. Sections stained with hematoxylin and eosin, Van Gieson's, and toluidine blue were studied. The presence or absence of edge neovascularization was noted. The other criteria were graded based on a semiquantitative scoring system. Results. Edge neovascularization was observed in 56% of the discs in the test group and in none of the control specimens. Fibrillation with fraying was the most significant finding in the test group (P < 0.001). Although the mean grades were higher in the test group, they did not predict the presence of edge neovascularization. Conclusions. Edge neovascularization was the most significant finding to confirm disc prolapse. Fibrillation with fraying, was observed more frequently in prolapsed intervertebral discs and the grades of fibrillation with fraying, chondrocyte cloning, and granular change were significantly higher in the test group. Pathologists can usually agree on the presence or absence of a particular histologic characteristic but are rarely consistent when they estimate the degree. Simple, reproducible agreed-on criteria are needed before semiquantitative evaluations become reliable.