Relevance of next-generation sequencing in the differential diagnosis of meningeal mesenchymal tumors: primary meningeal dedifferentiated chondrosarcoma of the cavernous sinus.

Primary mesenchymal tumors of the meninges include various types, with meningioma being the most prevalent. Non-meningothelial primary tumors of the meninges are uncommon and present diagnostic difficulties due to their potential morphological similarities with each other and with the anaplastic subtype of meningioma. Intracranial dedifferentiated chondrosarcoma is extremely rare and is defined by the presence of both a conventional chondrosarcoma component and a non-cartilaginous sarcoma component. Diagnosing this tumor can be particularly challenging in biopsy samples or when the chondrosarcoma component is not prominently represented. We report a rare case of dedifferentiated chondrosarcoma of the cavernous sinus in a specimen containing only the dedifferentiated component and exhibiting an IDH1 mutation, underscoring the importance of genetic characterization for the differential diagnosis of tumors in this anatomical region. Given the recent evidence supporting the efficacy of IDH inhibitors in chondrosarcomas, identifying mutations in these genes may also have significant therapeutic implications.