Abstract
A 54-year-old male with biopsy-confirmed Gleason 4+4 prostate cancer underwent (18)F-DCFPyL-PSMA PET scan to identify occult metastatic disease. This scan revealed abnormal radionuclide uptake not only in the prostate but also within the patient's vasculature. The scan was repeated after a week with a separate tracer batch, yielding the same result. Standard staging was performed using computed tomography and a Technetium-99 bone scan, revealing no metastatic disease. The patient's protein S deficiency is thought to have caused this peculiar tracer distribution. With the advent of PSMA PET for staging in prostate cancer, clinicians must be familiar with situations that may render unusual results.