Giant vertebral notochordal rest: a lesion distinct from chordoma: discussion of an evolving concept.

A 14-year-old boy with severe back pain for several years is described. Roentgenograms, bone scans, and computed tomographic scans of the spine were normal, but magnetic resonance imaging studies showed a lumbar vertebral body lesion, confined to the bone, with low T1- and high T2-weighted signal intensities. Histologically, the lesion consisted of sheet-like notochordal-type tissue, containing physaliphorous cells but lacking the usual features of chordoma. A diagnosis of giant notochordal rest was made. A review of prior possible examples of this recently described and controversial entity is made with a discussion of its embryologic foundations and distinction from chordoma.