Interesting ImagesNeurosarcoidosis Mimics High-Grade Glioma in Dynamic 18F-FET PET Due to LAT ExpressionUnterrainer, Marcus MD, MSc*†‡; Diekmann, Caroline*; Dorostkar, Mario MD§; Vettermann, Franziska Jill MD*; Kümpfel, Tania MD∥; Tonn, Jörg-Christian MD†‡¶; Bartenstein, Peter MD*†‡; Albert, Nathalie Lisa MD*†‡ Author Information From the *Department of Nuclear Medicine, University Hospital, LMU Munich; †German Cancer Consortium (DKTK), partner site Munich, Munich; ‡German Cancer Research Center (DKFZ), Heidelberg; and §Department of Neuropathology, ∥Institute of Clinical Neuroimmunology, and ¶Department of Neurosurgery, University Hospital, LMU Munich, Munich, Germany. Received for publication June 18, 2018; revision accepted July 20, 2018. Conflicts of interest and sources of funding: none declared. Correspondence to: Marcus Unterrainer, MD, MSc, Department of Nuclear Medicine University Hostpital, LMU Munich Marchioninistr. 15, 81377 Munich, Germany. E-mail: [email protected]. Clinical Nuclear Medicine: November 2018 - Volume 43 - Issue 11 - p 840-841 doi: 10.1097/RLU.0000000000002266 Buy Metrics Abstract We present a 45-year-old man with newly generalized tonic-clonic seizures due to a contrast-enhancing frontal lesion with perifocal edema suggestive for high-grade glioma (HGG). For further evaluation, a dynamic 18F-FET PET scan was performed, which showed high 18F-FET-uptake with early peak and constantly decreasing time-activity curves, a characteristic feature of HGG. Stereotactic biopsy and histological evaluation excluded a neoplastic lesion but confirmed a manifestation of neurosarcoidosis with strong expression of the L-amino-acid-transporter considered responsible for 18F-FET-uptake. Therefore, unknown manifestations of neurosarcoidosis represent a clinical pitfall in 18F-FET PET and can mimic HGG. Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved.