Polyostotic Fibrous Dysplasia Mimicking Widespread Skeletal Metastases on 68 Ga-PSMA PET/CT and Demonstrating a Superscan Pattern on Bone Scintigraphy.

Fibrous dysplasia (FD) may demonstrate increased 68 Ga-PSMA uptake and mimic skeletal metastases in prostate cancer. We present a 63-year-old man with newly diagnosed prostate cancer who underwent 68 Ga-PSMA PET/CT for staging. Imaging revealed widespread skeletal uptake involving multiple regions, raising suspicion for diffuse metastatic disease. Bone scintigraphy demonstrated a superscan pattern. However, CT showed characteristic benign features, including ground-glass appearance, bone expansion, and preserved cortical integrity. Histopathologic examination confirmed fibrous dysplasia. This case highlights a potential diagnostic pitfall of 68 Ga-PSMA PET/CT and emphasizes the importance of correlating metabolic findings with CT morphology to avoid misinterpretation and overstaging.