Ectopic thyroid in the adrenal gland.

We report two cases of intraadrenal thyroid gland tissue, both found by abdominal computed tomography (CT) scan and ultrasound echography. Histologically, the lesions were composed of mature thyroid follicles, varying in size, and some with cystic dilatation. Immunohistochemical staining for thyroglobulin confirmed their thyroid follicular nature. In neither case was there any evidence of thyroid gland cancer or teratomatous elements. Clinical examinations, including CT, ultrasound echography, and scintscanning did not show any tumorous lesions in the thyroid gland or elsewhere. The cause of ectopic thyroid in the adrenal gland is not known. It seems difficult to explain these ectopic lesions on the basis of developmental error because their location is distant from the path of embryological descent of the thyroid. The most important practical consideration is that they must be distinguished from metastatic deposits from a clinical point of view.