Systematic Review of Clinical, Radiologic, and Histologic Features of Benign Notochordal Cell Tumors: Implications for Patient Management

Background: There are no absolute defining criteria for benign notochordal cell tumors; the diagnosis is usually based on small size and the absence of aggressive features. Therefore, by definition, the diagnosis is subjective and usually determined by multidisciplinary consensus. A benign notochordal cell tumor should not grow during surveillance, and this may be used to confirm the diagnosis, but is a tautologic definition. Diagnostic ambiguity leads to uncertainty in management. If a tumor is a small chordoma then early surgery is likely to provide a better outcome. However, unnecessary treatment of a benign tumor may incur unjustified risk.

Objective: To propose clearer guidelines for the definition and management of benign notochordal tumors.

Methods: We performed a PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) review of the reported definitions for benign notochordal tumors and their management.

Results: The accepted features of benign notochordal tumors vary considerably: a typical tumor may be diagnosed in the absence of neurology, radiologically well-corticated bony margins, size <35 mm, no enhancement with contrast, no soft tissue extension, no dural penetration, no progression on scans, histologic absence of extracellular myxoid matrix, and low Ki67 index. If these criteria are fulfilled, it is reasonable to use radiologic surveillance in the first instance. Biopsy may be offered depending on the relative risks of performing the biopsy, or if there are atypical features.

Conclusions: We suggest a clearer definition for a benign notochordal tumor and a management algorithm that incorporates a level of diagnostic uncertainty.