Fibrous dysplasia as a possible false-positive finding in (68)Ga-labeled prostate-specific membrane antigen positron emission tomography/computed tomography study in the follow-up of prostate cancer

Positron emission tomography/computed tomography (PET/CT) using (68)Ga-labeled prostate-specific membrane antigen ((68)Ga-PSMA) has become an important tool in restaging patients with prostate cancer (PCa). Despite its high sensitivity and specificity, this method may produce false-positive findings, as indicated by previous studies. This case report aims to warn nuclear medicine physicians, oncologists, and urologists about the possibility of false-positive findings using this imaging modality, especially when the detected site is unusual for bone metastasis. A 68-year-old man with PCa underwent restaging tests after presenting with increased prostate-specific antigen. (68)Ga-PSMA PET/CT imaging revealed abnormal uptake in the left humeral head, which anatomically corresponded to the intramedullary and cortical sclerotic area. A biopsy was performed, and the pathology showed a lesion consisting of hard bone tissue with a small focal spot of fibrous dysplasia. Diagnostic issues related to (68)Ga-PSMA PET/CT imaging should be disseminated to help physicians make appropriate treatment choices for each patient.