Prostate carcinoma is the most common cancer in men. After local therapy, disease recurs in many patients. A choline PET/CT is indicated in case of biochemical relapse of prostate carcinoma to determine the site of recurrence (local and/or distant) and to help select the next line of therapy. Choline PET-CT is also known to show an elevated uptake in hyperfunctioning parathyroid adenoma. This case report shows the difficulty to distinguish between both entities if they occur simultaneously in an oncologic patient.