PRKCA D463H Mutation in Chordoid Glioma of the Third Ventricle: A Cohort of 16 Cases, Including Two Cases Harboring BRAFV600E Mutation.

Chordoid gliomas (CG) of the third ventricle are characterized by chordoid and glial features, but the extent of histological variations across CG is not fully understood. Herein, we report 16 consecutive cases of CG. All 16 patients had histories of headache and vision loss; their median age was 41.7 years at the surgery. Histological examination revealed typical features of CG, including cords of epithelioid cells within the mucinous stroma and lymphoplasmacytic infiltration. Two cases exhibited atypical histological features including histiocyte-like cells. PRKCA mutation was found in 14 cases, including the 2 with histiocytic features. BRAFV600E mutation was found only in the 2 cases with histiocytic features. The patients underwent gross total tumor resection without radiotherapy or chemotherapy. Three patients died between 1 and 4 months postsurgery. Only one had a recurrence. Eleven were alive at the most recent follow-up (range: 2-58 months). These data indicate that PRKCA mutation was a good diagnostic marker for CG and additionally suggest that histiocyte-like features can be present in CG in association with BRAF mutations.