FAPI PET Signal in Hibernoma Reflects FAP Expression in Tumor Vasculature Cells.

A 43-year-old man with a growing mass in the right groin, concerned for liposarcoma, underwent MRI and 68 Ga-fibroblast activation protein inhibitor (FAPI)-46 PET/CT before surgery. Fibroblast activation protein inhibitor PET/CT demonstrated increased uptake (SUV max , 3.2) predominantly in the solid portion, where MRI showed gadolinium enhancement. The patient subsequently underwent surgery and was diagnosed with hibernoma. The immunohistochemistry of the tumor revealed the fibroblast activation protein expression in the fibrovascular network and myofibroblastic cells of the tumor. This case suggests that the FAPI uptake can be affected by the vascular cells, and thus, a careful interpretation of the FAPI PET signal may be needed.

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Déclaration de conflit d'intérêts

Conflicts of interest and sources of funding: J.C. is the recipient of grants from the ERF-SNMMI (2019–2021 Molecular Imaging Research Grant for Junior Academic Faculty), the Philippe Foundation Inc (New York), and the ARC Foundation (France) (International Mobility Award SAE20160604150). J.C. is a consultant for Blue Earth Diagnostics, Curium Pharma, GE Healthcare, Janssen Pharmaceuticals, Progenics Radiopharmaceuticals, Radiomedix, and Telix Pharmaceuticals, outside of the submitted work. The study was partially funded by the ERF- SNMMI (2019–2021 Molecular Imaging Research Grant for Junior Academic Faculty). All other coauthors have no conflict of interest.