Genomic analysis of spinal meningiomas: correlation with histopathological grade

OBJECTIVE Spinal meningiomas are one of the most common primary intradural tumors of the adult spine. Spinal meningiomas typically have a benign course with low rates of recurrence. Recent advances in genomic profiling have provided valuable information on meningioma biology and natural history, but these studies have focused primarily on cranial meningiomas. Chromosomal copy number analysis of meningiomas has been shown to be a valuable molecular profiling technique for distinguishing benign from aggressive tumors. The Integrated Grade for Meningioma is a novel grading scheme that uses mitotic index and copy-number profile to identify aggressive tumors at high risk for recurrence. The integrated grade has been shown to be a better predictor of tumor behavior than WHO grade alone. The objective of this study was to evaluate the chromosomal copy-number profile of spinal meningiomas, and to correlate these findings with the assigned WHO grades. METHODS The authors evaluated 94 spinal meningiomas treated surgically at their institution between 2002 and 2022. The histopathological results including WHO grade, mitotic index, presence of atypical features, and MIB-1 index were recorded. Chromosomal copy number as determined by institutional whole-genome DNA copy-number profiling was available for 57 tumors. RESULTS The WHO grades of the cohort consisted of 81 (86%) WHO grade 1 tumors and 13 (14%) WHO grade 2 tumors. In tumors for which copy-number profiling was available, 44 (77%) of 57 demonstrated loss of 22q/NF2. Notably absent were frequent high-risk copy number alterations including loss of 1p, 3p, 4p/q, 6p/q, 10p/q, 14q, 18p/q, 19p/q, and focal loss of CDKN2A on 9p. Of the 9 WHO grade 2 tumors for which copy-number profiling was available, 6 tumors were reclassified to a lower risk profile (integrated grade 1). CONCLUSIONS This analysis suggests that spinal meningiomas exhibit overwhelmingly indolent biology, as supported by their benign integrated grade. These findings have implications in the surgical management of these patients in relation to the need for complete Simpson grade I resection, as well as the potential avoidance of adjuvant therapy following surgery in the setting of otherwise frequently benign pathology.