Part 2 book “Oxford textbook of neuro-oncology” has contents: Other tumours of the meninges, germ cell tumours, pituitary tumours, metastatic brain tumours, neoplastic meningitis - metastases to the leptomeninges and cerebrospinal fluid, familial tumour syndromes, and other contents. | CHAPTER 11 Meningiomas Rakesh Jalali, Patrick Y. Wen, and Takamitsu Fujimaki Epidemiology Meningiomas are the most common type of primary brain tumours in adults, accounting for 30% of the total (1, 2). The incidence of meningioma increases progressively with age. Meningiomas in children are rare, and usually associated with neurofibromatosis type 2 (NF2) or prior therapeutic radiation therapy (3, 4). Meningiomas are more common in women, with a female-to-male ratio of about 2:1 or 3:1 (3, 5). Spinal meningiomas, which account for 10% of all meningiomas, have an even higher female-to-male ratio of approximately 9:1. In contrast, the incidence in females is not significantly increased in atypical or anaplastic meningiomas, children, and radiation-induced meningiomas (4). Pathological classification The 2007 World Health Organization (WHO) classification of tumours of the central nervous system lists 15 subtypes of meningioma (Box ) (6). Nine of them are purely benign (grade I) tumours, whereas atypical meningioma, clear cell meningioma, and chordoid meningioma are grade II, and papillary meningioma, anaplastic meningioma, and rhabdoid meningioma are grade III. Histologically, atypical meningiomas are defined as meningiomas with loss of architectural pattern, prominent nucleoli, nuclear pleomorphism, increased mitotic activity, necrosis, and hypercellularity. They may invade the brain or show malignant histology. These tumours have a more aggressive natural history than benign tumours. WHO grade III malignant meningiomas exhibit frank histological malignancy or 20 mitotic figures per 10 high-power fields. Brain invasion does not necessarily imply WHO grade III meningioma; in the absence of 289 frank anaplasia (7), approximately 70–80% are WHO grade I, 5–35% are WHO grade II, and 1–3% are WHO grade III (8, 9). At the time of recurrence, most tumours retain the same histological pattern, but some exhibit a more advanced grade or a higher proliferative index .
