Abstract
BAP1-deficient meningiomas have a preferential infratentorial or spinal localization and may present with an undifferentiated histology of small or epithelioid cells rather than the meningothelial, rhabdoid or papillary variants. Frequent expression of cytokeratins may be misleading for a metastatic carcinoma but loss of BAP1 immunostaining in tumor cells and a specific methylation class enable the diagnosis. The clinical impact of the histomolecular diagnosis of BAP1-deficient meningioma is the high risk of relapse and a possible underlying BAP1 tumour predisposition syndrome.