A Review of Meningioma : The Most Common Intracranial Benign Tumour in Adults

Grossly term meningiomas describe group of tumours arising from meninges. It is a slow growing tumour. It can involve any age group and gender, however it is more common in elderly and in females. It is most common secondary malignancy attributed to radiation exposure. World Health Organization typically classifies it in three different grades. Grade I is benign, grade II atypical and grade III is considered malignant. Most of the meningiomas are benign. Surgery is the mainstay of treatment. Indication of adjuvant radiotherapy (RT) depends upon tumour grade and extent of resection. Both conventional fractionation and stereotactic radiosurgery are associated with good local control of disease. Role of Systemic treatment has not been yet established. EPIDEMIOLOGY Meningioma term is given by Harvey Cushing to represent a group of tumours arising from meninges. Meningiomas constitute about 20% of all primary intracranial tumours and are considered most common benign intracranial tumour in adults [1]. They can present in any age group, however more commonly they occur in sixth and seventh decade of life. In adults, females are more frequently affected than males. In pediatric age group meningiomas are less common, comprising only 1-4% of all intracranial tumours and there is no female predisposition. Meningiomas are mostly unifocal but might be mul-tifocal in 5-9% of cases [2]. Meningiomas seldom metastasize outside central nervous system [3]. Some common sites for meningiomas are cerebral convexities, falx cerebri, sphenoid ridge, cerebellar convexities and tentorium cerebelli. ETIOLOGY Several studies have shown development of intracranial men-ingioma in patients having previous history of scalp irradiation for tinea capitis disease, suggesting role of radiation exposure in pathogenesis of meningioma [4]. Radiation induced men-ingiomas are most common secondary malignancies. More common incidence in females, increase in meningioma related symptoms during pregnancy, progesterone receptor expression in 75% of meningiomas and more common occurrence in women on long acting hormonal contraceptives suggest important role of female sex hormones in etiology of menin-gioma [5,6]. The incidence of meningioma is also more common in some rare genetic diseases like neurofibromatosis type 2. Mutation in NF2 gene is most common associated genetic abnormality [7]. PATHOLOGY Meningiomas are firm, well circumscribed lesions tan to gray-ish in appearance. Most of the meningiomas are benign but few are malignant also. According to 2007 World Health Organization (WHO) grading criteria, meningiomas are classified in to 3 different grades. Grade I meningiomas are benign, constitute about 80% of all meningiomas and …