Clinicopathological features, imaging characteristics and surgical management in a novel tumour entity - aggressive meningiomas

Meningiomas are common neoplasms of the central nervous system, comprising between 24 and 30% of primary intracranial tumours, most commonly affecting females in their middle age or later adult life [1] [2]. Meningiomas are classified as benign, atypical or anaplastic meningiomas depending mostly on histopathological criteria known to be associated with worse prognosis in terms of tumour progression, recurrence risk after surgery and overall survival. The 2016 edition of the World Health Organization (WHO) classification of Central Nervous System (CNS) tumours recognizes brain invasion as an independent criterion for diagnosing an atypical grade II meningioma [3]. Meningioma grading based on the WHO classification of CNS tumours thoroughly impacts therapeutic management and tumour prognosis. Aggressive meningiomas, a different phenotype of tumours, characterized by rapid growth and involvement of adjacent brain tissue, blood vessels and bone, was not previously listed as an independent entity in the WHO classification of meningothelial-cell tumours.  Regarding the increasing importance of tumour grading in meningioma treatment strategies, the authors here provide an overview of clinicopathological and radiographic features, surgical management and long-term prognosis of this novel meningothelial tumour entity, the aggressive meningioma. In particular, we aimed to describe pre-, intra- and postoperative methods for recognizing aggressive meningiomas and explore the implications of this diagnosis on both surgical strategies and adjuvant therapy.

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.

Primary Anaplastic Ganglioglioma of the Temporal Lobe With Brainstem Involvement: A Case Report and Literature Review

Anaplastic ganglioglioma (AGG) is a rare and aggressive counterpart of the more benign and frequently encountered glioma. Herein, we present a 21-year-old female who presented with episodes of total amnesia and complex partial seizures, which led to the diagnosis of AGG localized to the medial temporal lobe. She subsequently underwent surgical cytoreduction of the tumor three times with adjuvant chemoradiotherapy. The extent of resection throughout the surgeries was hindered by the extension of the tumor to critical neurovascular structures; during the last surgery, invasion into the pons was noted, which posed a significant clinical challenge.