A pre operatory assessment by neck US, F-DOPA and F-choline PET/CT was performed in a 43-year-old MEN 2A woman affected by hyperparathyroidism and medullary thyroid carcinoma (MTC). On F-DOPA, two thyroid uptakes were analyzed as multifocal MTC and two others in the central neck compartment as MTC metastatic lymph nodes. After surgery, multifocal intra thyroidal MTC and two parathyroid glands hyperplasias were proved without MTC adenopathies. We report a case of rare false positive uptake on F-DOPA. In case of several endocrine diseases coexistence as in MEN 2A, F-DOPA should be carefully analyzed.