Uptake of [(18)F]DCFPyL in Paget's Disease of Bone, an Important Potential Pitfall in the Clinical Interpretation of PSMA PET Studies

Prostate-specific membrane antigen (PSMA)-targeted positron emission tomography (PET) imaging is an emerging technique for evaluating patients with prostate cancer (PCa) in a variety of clinical contexts. As with any new imaging modality, there are interpretive pitfalls that are beginning to be recognized. In this report, we describe the findings in a 63-year-old male with biochemically recurrent PCa after radical prostatectomy who was imaged with 2-(3-{1-carboxy-5-[(6-[18F]fluoro-pyridine-3-carbonyl)-amino]-pentyl}-ureido)-pentanedioic acid ([(18)F]DCFPyL), a small-molecule inhibitor of PSMA. Diffuse radiotracer uptake was noted throughout the sacrum, corresponding to imaging findings on contrast-enhanced computed tomography (CT), bone scan, and pelvic magnetic resonance imaging consistent with Paget's disease of bone. The uptake of [(18)F]DCFPyL in Paget's disease most likely results from hyperemia and increased radiotracer delivery. In light of the overlap in patients affected by PCa and Paget's disease, it is important for nuclear medicine physicians and radiologists to be aware of the potential for this diagnostic pitfall when interpreting PSMA PET/CT scans. Correlating findings on conventional imaging such as diagnostic CT and bone scan can help confirm the diagnosis.