Meningiomas With Rhabdoid Features Lacking Other Histologic Features of Malignancy: A Study of 44 Cases and Review of the Literature

Abstract

The behavior of rhabdoid meningiomas otherwise lacking malignant features remains unknown as most of the originally reported aggressive cases showed anaplastic histologic features independently of rhabdoid phenotype. We studied 44 patients with rhabdoid meningiomas lacking anaplastic features. Median age at diagnosis was 48.6 years (range 10-79). Location was supratentorial in 28 (63.6%), skull base in 15 (34.1%), and spinal in 1 (2.3%). Tumor grade was otherwise World Health Organization grade I (n = 22, 50%) or II (n = 22, 50%). Rhabdoid cells represented <20% of the tumor in 12 cases (27.3%), 20% to 50% in 18 (40.9%), and >50% in 14 (31.8%). Median clinical follow-up, available for 38 patients, was 5.0 years (range 0.17-14.2). Recurrence occurred in 9 patients (5-year recurrence-free survival, 73.7%) with a significantly higher risk in subtotally resected tumors (p = 0.043). Rhabdoid cell percentage was not associated with recurrence. Six patients died (4 of disease, 2 of unclear causes); 5-year overall survival was 86.7%, a mortality in excess of that expected in grade I-II meningiomas but much lower than originally reported. Review of 50 similar previously reported cases confirmed our findings. We suggest that rhabdoid meningiomas be graded analogously to nonrhabdoid tumors, with caution that some may still behave aggressively and close follow-up is recommended.

Genomic landscape of high-grade meningiomas

“…Independent of histologic grade, we observe frequent gains across the genome in multiple chromosomes in angiomatous meningiomas [32]. Rhabdoid meningiomas are considered to be grade III tumors by WHO guidelines [43], but recent reports have proposed that the histolopathologic finding of rhabdoid features may be found in meningiomas of each of the three WHO grades. In our cohort, rhabdoid meningiomas harbored loss of chromosome 1p significantly less frequently than grade II–III meningiomas of other histologic subtypes.…”

DNA methylation-based classification and grading system for meningioma: a multicentre, retrospective analysis

“…Although oftenthis was based on small series, it prompted the allocation allotment of distinct WHO grades to specific meningioma subtypes. However, this approach has been increasingly questioned due to suboptimal inter-observer reproducibility 7,23 , most recently reported in a large Radiation Therapy Oncology Group …”

Molecular and translational advances in meningiomas

“…For example, tumors with predominantly clear-cell or chordoid histological morphology are by definition classified as grade II, while rhabdoid and papillary meningiomas are classified as grade III, although some grading controversies remain for these rare subtypes. 3,4 Although the extent of mitotic activity observed is an essential grading criterion for this tumor, its detection is confounded by many factors, including sampling bias in a heterogeneous tumor, as well as technical factors and the experience of the pathologist. 5 The degree of mitotic activity is an indicator of the proliferative potential of the tumor.…”