High PSMA Avidity, Yet Still Benign: The Importance of CT Morphology for Diagnosing Fibrous Dysplasia on PSMA-Targeted PET/CT.

A 64-year-old man with newly diagnosed prostate cancer underwent 18 F-Piflufolastat PET/CT. Radiotracer avidity localized to the primary prostate malignancy and to a left rib (SUV max , 9.0). The high 18 F-Piflufolastat avidity may have been mistaken for a metastasis if not for the corresponding CT images demonstrating a well-circumscribed sclerotic rim at the site of the PET focus. This CT finding is uncommon for osseous malignancy, but common in benign fibrous dysplasia. Biopsy confirmed benign fibrous dysplasia. This case emphasizes that benign CT morphology may supersede even high avidity on PSMA-targeted PET imaging. Physicians interpreting PET/CT must recognize CT findings that supersede PET findings.