SMARCE1 mutation screening in classification of clear cell meningiomas

AIMS: Clear cell meningioma is a rare subtype of meningioma and shows not only unusual histology, but also unique clinical features. Recently, SMARCE1 mutations have been shown to cause spinal and cranial clear cell meningiomas. We present 12 cases which were diagnosed with a clear cell meningioma in a single institution between 1997 and 2014, and investigate their SMARCE1 mutation status.

METHODS AND RESULTS: To investigate the SMARCE1 mutation status of these tumours, we used a combination of Sanger sequencing and multiplex ligation dependent probe amplification analysis and also performed SMARCE1 immunohistochemical staining. We found both SMARCE1 mutational hits, including novel SMARCE1 mutations, in six out of eight tested patients. Immunohistochemical analysis showed loss of SMARCE1 protein staining in all but two cases. Two individuals who were originally diagnosed with clear cell meningioma were negative for SMARCE1 mutations, but tested positive for NF2 mutations. As a result, these two tumours were reanalyzed and eventually reclassified, as a microcystic and a mixed growth pattern meningioma with focal clear cell areas, respectively.

CONCLUSIONS: These results expand the spectrum of pathogenic variants in SMARCE1 and show that mutation screening can help facilitate meningioma classification. This may have implications for prognosis and future clinical management of patients, since clear cell meningiomas are classed as grade II tumours, while microcystic and meningothelial meningiomas are classed as grade I. This article is protected by copyright. All rights reserved.