Sacral Insufficiency Fracture Mimicking Metastatic Prostate Cancer on 18 F-PSMA-1007 PET/CT

Accurate diagnosis of sacral insufficiency fractures in oncology patients may be challenging. We describe 18 F-PSMA-1007 PET/CT findings of sacral insufficiency fracture in a patient with a history of prostate cancer and pelvic radiotherapy. The insufficiency fracture in the left sacral ala showed no oblivious structural changes and diffuse heterogeneous activity with SUV max of 7.7 on 18 F-PSMA-1007 PET/CT mimicking metastatic prostate cancer. A follow-up 99m Tc-MDP SPECT/CT showed progression of the insufficiency fracture from the left sacral ala to the right sacral ala. A low level of serum prostate-specific antigen may be helpful for the diagnosis.