SMARCE 1 mutation screening in classification of clear cell meningiomas

Aims Clear cell meningioma ( CCM ) is a rare subtype of meningioma and shows not only unusual histology, but also unique clinical features. Recently, SMARCE 1 mutations have been shown to cause spinal and cranial CCM s. We present 12 cases which were diagnosed with CCM in a single institution between 1997 and 2014, and investigate their SMARCE 1 mutation status. Methods and results To investigate the SMARCE 1 mutation status of these tumours, we used a combination of Sanger sequencing and multiplex ligation‐dependent probe amplification analysis and also performed SMARCE 1 immunohistochemical staining. We found both SMARCE 1 mutational hits, including novel SMARCE 1 mutations, in six of eight tested patients. Immunohistochemical analysis showed loss of SMARCE 1 protein staining in all but two cases. Two individuals who were diagnosed originally with CCM were negative for SMARCE 1 mutations, but tested positive for NF 2 mutations. As a result, these two tumours were re‐analysed and eventually reclassified, as a microcystic and a mixed pattern of meningothelial meningioma with focal clear cell areas, respectively. Conclusions These results expand the spectrum of pathogenic variants in SMARCE 1 and show that mutation screening can help to facilitate meningioma classification. This may have implications for prognosis and future clinical management of patients, as CCM s are classed as grade II tumours, while microcystic and meningothelial meningiomas are classed as grade I.