H3 K27M mutation in rosette-forming glioneuronal tumors: a potential diagnostic pitfall

This study aimed to assess whether RGNTs, similar to other midline tumors, may exhibit immunohistochemical loss of H3 K27me3 and harbor theH3 K27M mutation.All seven analyzed RGNTs displayed immunohistochemical loss of H3 K27me3 in all tumor cells or H3 K27me3 mosaic immunostaining. In one case, H3 K27me3 loss was associated with theH3 K27M mutation, whereas the other six cases did not exhibit anyH3 mutations or EZHIP overexpression. During a follow-up period of 23 months, theH3 K27M-mutant case remained unchanged in size despite partial resection, indicating that theH3 mutation may not confer higher biological aggressiveness to RGNT.The immunohistochemical loss of H3 K27me3 co-occurring with theH3 K27M mutation may result in the potential misdiagnosis of RGNT, especially in cases of small biopsy specimens consisting of only the glial component.
Source: Virchows Archiv - Category: Pathology Source Type: research