Table 1.
Distribution of F3T3 diffuse gliomas according to WHO grading and IDH status
| Histological Entity | FGFR3-TACC3 Fusions Identified/Samples Tested | |
|---|---|---|
| Without Prescreening for FGFR3 Immunopositivity | Prescreened for FGFR3 Immunopositivity | |
| Diffuse glioma (grade II-IV), IDH mutant | 0/187 | 0/6 |
| Grade II glioma, IDH wildtype | 2/24 (8.3%) | 4/6 (66.7%) |
| Grade III glioma, IDH wildtype | 1/56 (1.8%) | 5/19 (26.3%) |
| Glioblastoma, IDH wildtype | 21/588 (3.6%) | 42/84 (50%) |
| Diffuse glioma NOS, IDH wildtype | 0/7 | 1/60 (1.7%) |
| Diffuse glioma (grade II-III), IDH NOS | 0/7 | 0/6 |
| Glioblastoma, IDH NOS | 0/82 | 4/30 (13.3%) |
| Total | 24/951 (2.5%) | 56/211 (26.5%) |
NOS = not otherwise specified. Note. Twenty-four F3T3 cases were identified from a systematic screening of 951 gliomas from Pitié-Salpêtrière tumor bank without FGFR3 IHC pre-screening (frequency of F3T3 fusions among unselected diffuse gliomas, grades II–IV: 2.5%), while 56 F3T3 cases were detected from an additional series of 211 preselected gliomas with FGFR3 protein immunopositivity (frequency of F3T3 fusions among FGFR3-immunopositive tumors: 26.5%).