Benign notochordal cell tumors of the spine: natural history of 8 patients with histologically confirmed lesions.

Abstract

Notochord-related lesions of the spinal column include benign notochordal cell tumors (BNCTs), ecchordosis physaliphora, both generally considered benign lesions, and chordomas, which represent malignant tumors. The histological similarity of these lesions to the notochord and each other and their strong predilection to the axial skeleton have led to the hypothesis that these lesions represent a continuum of malignant transformation from notochordal remnants, BNCTs, and finally chordomas. To present a cohort of biopsy-proven BNCTs with a description of radiographic features, histology, and follow-up to help elucidate the optimal management of these lesions. A retrospective chart review identified 13 patients with notochordal rest lesions confirmed by histology. Histologic inclusion criteria included notochordal features without evidence of septation, myxoid matrix, nuclear atypia, or mitotic figures. Tumors exhibiting evidence of cortical expansion or destruction were excluded. The natural history and histological and radiographic features were examined. Sixteen spinal lesions from 8 patients met the diagnostic criteria for BNCTs, identified on imaging after the patient presented with back pain. Radiographically, all lesions were hypointense on T1-weighted magnetic resonance imaging sequences and hyperintense on T2-weighted and short T1 inversion recovery. The median radiographic follow-up was 21.6 months (range, 8.5-71.2 months). None of the lesions exhibited radiographic or symptomatic progression. Although limited by short follow-up, our series confirms that these lesions may be safely observed without evidence of malignant transformation, which emphasizes the importance of distinction of BNCT from chordoma at diagnosis and the possibility of close follow-up for these lesions instead of aggressive treatment indicated in patients with chordomas.