Fibrous Dysplasia Mimicking Skeletal Metastasis on 68Ga-FAPI PET Imaging

Ga-68-labeled fibroblast activation protein inhibitor (Ga-68-FAPI) PET imaging has been introduced for detecting many primary and metastatic tumors. However, false-positive uptakes have been reported in some benign lesions. Here, we presented a Ga-68-FAPI-avid lesion in the left temporal bone in a 41-year-old man with a history of signet ring cell gastric adenocarcinoma. The osseous lesion was finally distinguished as fibrous dysplasia according to the clinical and imaging findings. This case suggests that Ga-68-FAPI may have false-positive uptakes in bone benign lesions, which should be paid attention to in the diagnosis of bone lesions in patients with malignant tumors.