Most meningiomas are benign, non-cancerous and slow growing tumours, but a proportion of meningioma grow rapidly, relentlessly and are fatal.
Based on their appearance under the microscope, World Health Organisation (WHO) classification of tumours recognises three grades of meningiomas: benign (grade 1), atypical (grade 2) and malignant (grade 3). The purpose of this classification is to predict behaviour and prognosis, and to plan management. WHO grade 1 meningiomas are most common (80%) with a low recurrence rate. WHO grade 2 meningiomas, comprise about 10-15% of meningiomas and have a higher recurrence rate after treatment compared to WHO I meningioma. Based on this characteristic, atypical meningiomas should be followed up closely after surgical resection, and may have additional treatment with radiotherapy. WHO III meningiomas have the highest tendency for rapid growth and for regrowth after treatment. Although malignant meningiomas only comprise 1-3% of meningiomas their treatment can be challenging due to their aggressive nature.
In the future, molecular markers will likely play a major role in meningioma classification and deciding on management.
Meningiomas are often referred to as brain tumours but they do not grow from brain tissue itself. They usually arise from the surface of the brain at any location either on the top part of the head or beneath the brain. The spinal canal is another possible site of origin. The site of the tumour often dictates how difficult the tumour is to access for surgery. The involvement of nerves or blood vessels is a further important consideration when planning surgery, and when estimating the risk of surgery.
Written by Alireza Shoakazemi for BIMS