18F-Fluciclovine Uptake in Thymoma Demonstrated on PET/MRI

Abstract

A 68-year-old man with a history of prostate cancer post–primary treatment presented with rising prostate-specific antigen levels and was referred for 18F-fluciclovine PET/MRI to localize recurrent disease. PET/MRI revealed a solitary focus of uptake in a soft tissue nodule in the anterior mediastinum, which was resected and found to be a type B2 thymoma. 18F-fluciclovine uptake is mediated by amino acid transporters, primarily alanine-serine-cysteine transporter 2 and l-type amino acid transporter 1, previously demonstrated to be expressed on thymic carcinomas. This case highlights the possibility of overexpression of amino acid transporters in thymomas as well, rarely described before.

18F-Fluciclovine Uptake in Intramuscular Injecting Site of Antiandrogen

“…2 However, it is not specific for prostate cancer and has been found to be present in variety of malignant and benign etiologies. [3][4][5][6][7][8][9][10][11][12][13][14][15] With the COVID-19 pandemic and rapid application of vaccination recently, increasing uptake of 18 F-fluciclovine has also been discovered in the vaccination-related lymphadenopathy. 16,17 The positivity rate of 18 F-fluciclovine may not be compromised by antiandrogen therapy, which means that the antiandrogens are not necessarily stopped before the 18 F-fluciclovine scan.…”

“…18 F-fluciclovine is a radiolabeled amino acid analog and has been approved by US Food and Drug Administration for detecting prostate adenocarcinoma with upregulation of the amino acid transport 2 . However, it is not specific for prostate cancer and has been found to be present in variety of malignant and benign etiologies 3–15 . With the COVID-19 pandemic and rapid application of vaccination recently, increasing uptake of 18 F-fluciclovine has also been discovered in the vaccination-related lymphadenopathy 16,17 .…”