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Nuklearmedizin 2025; 64(02): 173-174
DOI: 10.1055/a-2383-2584
Case Report

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

Laura Ternoy
1   Dermatology, CHU de Rennes, Rennes, France (Ringgold ID: RIN36684)
,
Pierre Meneret
2   Nuclear Medicine, Centre Eugene Marquis, Rennes, France (Ringgold ID: RIN56479)
,
Xavier Palard-Novello
3   Bretagne, Centre Eugene Marquis, Rennes, France (Ringgold ID: RIN56479)
,
David Russo
1   Dermatology, CHU de Rennes, Rennes, France (Ringgold ID: RIN36684)
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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.

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