The thyroid gland is virtually unique since it can be affected by both external
radiation (and thus, it shares with other organs histopathologic changes due to
irradiation effects) and by the so-called "internal" radiation, wherein administration of
radioactive iodide preferentially affects the thyroid gland (almost to the exclusion of all
other organs). This review will focus on both types of radiation and the changes that can
be seen acutely and chronically in the thyroid after it has been subjected to irradiation.
In addition, the neoplastic potential of radiation exposure on thyroid follicular
epithelium will be presented and illustrated.
Keywords: Radiation, carcinoma, thyroid, thyroiditis.
