[Report of seven cases of clear-cell meningioma and a literature review]

Abstract

Aims: Clear cell meningioma (CCM) is a rare variant of meningioma, which is important to distinguish because of its aggressive behaviour. Sixty-eight cases have been previously described in the literature. In this retrospective study, we report seven cases of CCM operated in our institution between 1994 and 2008.

Methods: Seven CCM cases were retrieved from the files of our pathology department. Clinical and radiological data were reviewed. A standard histological study was realized and immunohistochemistry was performed with epithelial membrane antigen (EMA), cytokeratin KL1, progesterone receptors, Ki-67 (MIB-1), S100 protein.

Results: Patients' age ranged from 2 to 70 years (median age: 36 years), with a female predominance (5/7 patients). Three patients belonged to the same family, probably affected by neurofibromatosis type 2. CCM occurred in various locations: medullary region (two), sphenoid wing (two), ponto-cerebellar angle (two), tentorium (one). The tumour could be fully resected in three cases. Follow-up ranged from 3 months to 15 years: recurrence occurred in four patients, three of whom eventually died from the disease.

Discussion: In our series, the frequency of CCM (0,6% of all meningiomas operated on in our institution) and its histological aspects are almost identical to those observed of the literature. We discuss the predictive value of proliferation index (MIB-1) and the role of patient status and quality of surgical resection in the evolution.

Conclusion: Our study supports the fact that MCC course is less favourable than meningioma WHO grade I, even in the absence of anaplastic area, high mitotic activity, or necrosis. In this series, MIB-1 index was of no interest identifying patients with or without recurrence.