A 84-year-old male patient with prostate adenocarcinoma underwent technetium-99m (Tc-99m) methylene diphosphonate (MDP) whole body bone scintigraphy in order to evaluate bone metastasis. The patient did not have any other known diseases or complaints. The bone scintigraphy showed focal increased activity in the area consistent with the inferior pole of the left lobe of the thyroid gland. The serum thyroid function tests were as follows: TSH 2.45 uIU/mL (N: 0.34-5.60), fT3: 3.52 pg/mL (N: 2.5-3.9), fT4: 0.76 ng/dL (N: 0.58-1.6) and thyroid autoantibodies were negative