Intense 68 Ga-FAPI-04 Uptake in a Rare Case of Multifocal Abdominal Wall Endometriosis

Fibroblast activation protein inhibitor (FAPI) PET is an emerging molecular imaging modality that is widely used in oncology and increasingly investigated in nononcologic diseases. Abdominal wall endometriosis (AWE) is a rare form of endometriosis, characterized by ectopic endometrial tissue in the abdominal wall. We present a patient with a right external obturator mass, biopsy-confirmed as endometriosis, in whom 68 Ga-FAPI-04 PET/CT revealed extensive multifocal AWE and adenomyosis. These lesions demonstrated intense FAPI uptake, in contrast to their low or absent FDG uptake. This case highlights the potential of FAPI PET for detecting atypically located endometriosis, a capability lacking in current imaging methods.