Atypical meningioma: Motto: “Scientific observation is allways a polemic observation” - Gaston Bachelard

Abstract

Objective: Atypical meningioma are an intermediate group of meningiomas, exhibiting less favourable biological behavior than classic benign tumours, but a relatively more favourable biological behavior than definitive malignant meningiomas. Subject of controversy, atypia in meningioma still generate discordance between accurate criteria defining malignancy and biological behavior, prediction of recurrence.
Methods: This retrospective study intend to evaluate diagnosis on clinical and pathological data, treatment trends and early outcomes for 6 cases with atypical meningiomas occuring in 63 patients operated for benign meningioma in the last 5 years in our clinic between 2006-2011. All patients were explored CT, MRI, preoperative selective angiography and in all cases the WHO 2000 classification criteria were used to define atypical meningioma
Results: Between 2006-2011 we operated 6 atypical meningioma of 63 benign meningiomas (9,52%). Tumor sites in the patients were: parasagittal (3 cases), convexity (2 cases), spheno-cavernous (1 case). All patients were operated and dural graft was done to all cases. The extent of surgical resection was Simpson’s grade 1 in 2 cases and Simpson’s grade 2 in four cases, to which radiation was administered after the first surgery with a dose ranging from 52-62 Gy. Regrowth (enlargement of tumour after subtotal resection) was noticed in 2 irradiated cases: one case after 2 years after the first operation, the patient was again operated - pathological diagnosis was malignant meningioma; in another case after 3 years, at operation it was the atypical meningioma. No chemotherapy was used in our cases.
Conclusions: Atypical meningiomas are rare tumors, grow more rapidely, the diagnosis age ? 60 years, several histological criteria can define accurate identification to understand the biology of this group of tumors. Heterogenous contrast enhancement with marked peritumoral edema in neuroimaging are important; cerebral edema has prognostic value and should encourage fundamental and farmacologic research using anti VEGF and somatostatine analogs treatments. Surgery (Simpson grade 1) referring both tumor and dural implant area should be done de novo but also for recurrencies. Radiotherapy still are controversial without proven benefit and chemotherapy without statistic argues to improve quality of life.