Imaging characteristics, histopathological features and surgical considerations regarding aggressive meningiomas

Meningiomas are tumours of the meninges that arise primarily from arachnoidal cap cells, but they can also occur rarely as primary tumours in other localizations, such as within the ventricles. They stand for 24-30% of primary intracranial tumours and affect mostly women in their middle age or later adult life [1, 2]. Meningiomas can be classified, according to the World Health Organization (WHO) classification of Central Nervous System (CNS) tumours, as benign (grade I, most frequently encountered type), atypical (grade II) or anaplastic (grade III), based mostly on histopathological criteria known to be associated with tumour progression, recurrence risk and survival. Since meningioma grading based on the WHO classification is the most important factor determining therapeutic management and tumour prognosis, there has been an increasing interest in adding new criteria for better characterization of these tumours. Thus, the 2016 edition of the WHO classification recognized brain invasion as an independent criterion for atypical (grade II) meningioma diagnosis [3]. However, meningiomas that display aggressive features such as rapid growth and higher recurrence rate, can also involve blood vessels and bone. Hence, the authors aim to describe a different entity, aggressive meningiomas, not previously listed as a tumour phenotype in the WHO classification of meningothelial-cell tumours, with regard to pre-, intra- and postoperative methods for diagnosis and explore the implications on surgical strategies and adjuvant therapy.