Giant Cell Tumor of Bone With Intense PSMA PET/CT Avidity Simulating Bone Metastasis From Prostate Cancer

We report the case of a 74-year-old man with recurrence of prostate adenocarcinoma (PSA: 0.21 ng/mL) after radical prostatectomy. PSMA-PET/CT revealed intense uptake (SUVmax: 7.5) in an osteolytic lesion of the right femoral neck. Surgery was undertaken to prevent pathologic fracture. Histopathologic findings were consistent with a giant cell tumor of bone (GCTB). PSMA is expressed in endothelial cells of tumor neovasculature, explaining uptake in nonprostatic bone tumors. The case we report demonstrates that PSMA-PET/CT reflects vascular activity and may mimic metastasis, as prostate cancer metastases are usually sclerotic but can present as lytic lesions in the early stages.