Biopsy-Proven Diffuse Mediastinal Prostate Cancer Metastases Negative on 18F-Fluorocholine, Diagnosed on 68Ga-PSMA and 18F-PSMA PET/CT.

A 72-year-old man with prostate cancer (stage T3b, Gleason score 7) treated by radical prostatectomy was found to have biochemical failure (prostate-specific antigen 8.5 ng/mL) and a suspicious growing nodularity at the left prostate bed on MRI. F-fluorocholine PET/CT failed to demonstrate any site of uptake suggestive of malignancy. A bone scan did exclude bone metastases. Ga-PSMA PET/CT revealed various positive lymph nodes in the supraclavicular, mediastinal, and hilar regions. This was confirmed on F-DCFPyl PET/CT, with the addition of a suspicious right axillary lymph node. Mediastinal biopsy confirmed metastatic prostate cancer.