Fibrous Dysplasia With 99m Tc-FAPI Uptake in a Patient Under Long-term Antiresorptive Therapy.

We report a rare case of a 40-year-old woman with longstanding craniofacial fibrous dysplasia involving the right maxilla, orbital cavity, and fronto-parietal bones. The patient underwent partial maxillary debulking 7 years ago for cosmetic reasons and orbital decompression 3 years ago, and is currently on long-term antiresorptive therapy. Bone scintigraphy with 99mTc-MDP showed multiple sites of increased osteoblastic activity. 99mTc-FAPI SPECT/CT also revealed focal uptake in craniofacial and other lesions, indicating active fibroblast proliferation. This is the first reported case of 99mTc-FAPI uptake in fibrous dysplasia, suggesting its value in evaluating fibrotic bone lesions.