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

Accurate diagnosis of sacral insufficiency fractures in oncology patients may be challenging. We describe 18F-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 SUVmax of 7.7 on 18F-PSMA-1007 PET/CT mimicking metastatic prostate cancer. A follow-up 99mTc-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.