Detection of GRM1 gene rearrangements in chondromyxoid fibroma: a comparison of fluorescence in-situ hybridisation, RNA sequencing and immunohistochemical analysis.

GRM1 gene rearrangements can be detected using FISH break-apart probes in approximately 75% of cases, and immunohistochemical detection of GRM1 protein over-expression is a sensitive diagnostic method. The gene fusion was not detected by targeted RNA sequencing, due most probably to the complexity of fusion mechanism, and is not yet a reliable method for confirming a diagnosis of CMF in the clinical setting.