Mediastinal ectopic thyroid are rare findings corresponding to about 1% of cases of ectopic thyroid, having a prevalence of 100,000-300,000 for healthy people. The case report corresponds to a patient whose finding of a deep and dipping nodule in the cervical region was occasional. After being submitted to cervical ultrasonography and computed tomography, the patient underwent resection of the ectopic thyroid, whose histology revealed foci of follicular hyperplasia and remnants of thymus, without atypia and with good outcome.