T2-FLAIR Mismatch Sign in Pediatric Low-Grade Glioma
Matthias Wagner, Liana Nobre, Khashayar Namdar, Farzad Khalvati, Uri Tabori, Cynthia Hawkins, Birgit Ertl‐Wagner
Abstract
<h3>BACKGROUND AND PURPOSE:</h3> No qualitative imaging feature currently predicts molecular alterations of pediatric low-grade gliomas with high sensitivity or specificity. The T2-FLAIR mismatch sign predicts <i>IDH</i>-mutated 1p19q noncodeleted adult gliomas with high specificity. We aimed to assess the significance of the T2-FLAIR mismatch sign in pediatric low-grade gliomas. <h3>MATERIALS AND METHODS:</h3> Pretreatment MR images acquired between January 2001 and August 2018 in pediatric patients with pediatric low-grade gliomas were retrospectively identified. Inclusion criteria were the following: 1) 0–18 years of age, 2) availability of molecular information in histopathologically confirmed cases, and 3) availability of preoperative brain MR imaging with non-motion-degraded T2-weighted and FLAIR sequences. Spinal cord tumors were excluded. <h3>RESULTS:</h3> Three hundred forty-nine patients were included (187 boys; mean age, 8.7 [SD, 4.8] years; range, 0.5–17.7 years). <i>KIAA1549</i>–B-Raf proto-oncogene (<i>BRAF</i>) fusion and <i>BRAF</i> p.V600E mutation were the most common molecular markers (<i>n</i> = 148, 42%, and <i>n</i> = 73, 20.7%, respectively). The T2-FLAIR mismatch sign was present in 25 patients (7.2%). Of these, 9 were dysembryoplastic neuroepithelial tumors; 8, low-grade astrocytomas; 5, diffuse astrocytomas; 1, a pilocytic astrocytoma; 1, a glioneuronal tumor; and 1, an angiocentric glioma. None of the 25 T2-FLAIR mismatch pediatric low-grade gliomas were <i>BRAF</i> p.V600E–mutated. Fourteen of 25 pediatric low-grade gliomas with the T2-FLAIR mismatch sign had rare molecular alterations, while the molecular subtype was unknown for 11 tumors. <h3>CONCLUSIONS:</h3> The T2-FLAIR mismatch sign was not observed in the common molecular alterations, <i>BRAF</i> p.V600E–mutated and <i>KIAA1549-BRAF</i> fused pediatric low-grade gliomas, while it was encountered in pediatric low-grade gliomas with rare pediatric molecular alterations.