18 F-DOPA PET Silence in High-grade Glioma Subtype F : A Distinct Metabolic Phenotype.

Quéré, Chloé; Bielle, Franck; Picca, Alberto; Nichelli, Lucia; Mathon, Bertrand; Kas, Aurélie; Rozenblum, Laura · Clin Nucl Med · 2026

case_report · Level V

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Abstract

The 2021 WHO classification distinguishes adult-type diffuse gliomas as astrocytoma, oligodendroglioma, and glioblastoma. Recently, a new epigenetic subtype-high-grade glioma IDH-wildtype, subtype F (HGG-F)-has been described, characterized by gliomatosis-like infiltration, low proliferative index, and unexpectedly prolonged survival despite a grade 4 methylation profile. We report the first HGG-F evaluated with 18 F-DOPA PET. Despite extensive FLAIR-hyperintense lesions, tracer distribution was entirely normal. This "amino acid PET silence," contrasting with the typically intense uptake in high-grade gliomas, together with the gliomatosis-like MRI appearance, should raise suspicion for this emerging subtype.

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