Persistence of an increased CEA in case of colon adenocarcinoma without any secondary localization leading to the discovery of a MTC has already been reported [39,40,41] but for the first time, we report the contribution of 18F-FDOPA PET/CT in the pre-surgical characterization of a thyroid nodule. This evidence concerns the gene CEACAM5 and medullary thyroid gland carcinoma.