Unusual growth pattern of a meningioma

Clinical, Histopathologic and Genetic Features of Rhabdoid Meningiomas

Rhabdoid meningiomas (RM) shows heterogeneous histological findings, and a wide variety of chromosomal copy number alterations (CNA) are associated with an unpredictable course of the disease. In this study, we analyzed a series of 305 RM samples from patients previously reported in the literature and 33 samples from 23 patients studied in our laboratory. Monosomy 22-involving the minimal but most common recurrent region loss of the 22q11.23 chromosomal region was the most observed chromosomal alteration, followed by losses of chromosomes 14, 1, 6, and 19, polysomies of chromosomes 17, 1q, and 20, and gains of 13q14.2, 10p13, and 21q21.2 chromosomal regions. Based on their CNA profile, RM could be classified into two genetic subgroups with distinct clinicopathologic features characterized by the presence of (1) chromosomal losses only and (2) combined losses and gains of several chromosomes. The latter displays a higher frequency of WHO grade 3 tumors and poorer clinical outcomes.

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

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.