A metastatic melanoma with an atypical low 18F-FDG uptake

This is the authors' abstract. We don't add key points for this paper.

Introduction 18F-FDG PET/CT is a valuable tool for staging and treatment monitoring of melanoma, as melanoma cells usually present with a high avidity for 18F-FDG [ 1 ] [ 2 ]. However, there are some common and specific pitfalls that can lead to false-positives and false-negatives [ 3 ]. False-positives are often due to infections or inflammatory diseases [ 4 ]. When monitoring response to immune checkpoint inhibitors, particular attention must be paid to pseudoprogression or to immune related effects. False-negatives may occur for reasons related to patient preparation such as incomplete fasting, hyperglycaemia or hyperinsulinaemia [ 5 ]. Antitumoral medication, if started before the baseline scan, or anti-inflammatory drugs such as glucosteroid (which can also cause hyperglycaemia) may also reduce 18F-FDG uptake. Necrotic lesions may show reduced or no uptake, and small lesions (e.g., in-transit metastases) are prone to partial volume effect. BRAF mutation status is an important parameter in the management of melanoma but does not appear to correlate with 18F-FDG uptake. Publication History Received: 05 August 2024 Accepted: 06 August 2024 Article published online: 04 December 2024 © 2024. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany