NF2 mutations in secretory and other rare variants of meningiomas.

The WHO classification defines different histological variants of meningiomas. Mutations of the tumor suppressor gene NF2 on 22q have been described in 30% to 60 % of sporadic meningiomas. However, the vast majority of the meningiomas that have been subject to NF2 analysis belong to the most frequent variants like transitional, fibroblastic and meningothelial meningiomas. Within these subtypes, transitional and fibroblastic meningiomas harbor significantly more NF2 mutations than meningothelial meningiomas, indicating molecular subsets of these tumors. To determine whether rare meningioma variants carry NF2 mutations we analyzed 80 tumors. NF2 mutations were detected in 5 (36%) of 14 psammomatous, 1 (11%) of 9 angiomatous, 2 (22%) of 9 clear cell, 1 (33%) of 3 chordoid and 1 (100%) of 1 papillary meningioma. In the single papillary meningioma, 2 different NF2 mutations were observed. No NF2 mutations were found in 33 secretory, 7 microcystic, 2 lymphoplasmacyte-rich, one rhabdoid and one metaplastic meningioma. In the control group of 25 fibroblastic meningiomas, 11 cases were identified to carry an NF2 mutation. These results support the concept of different molecular subgroups of meningiomas which overlap with histological variants.