Abstract
Riedel's thyroiditis is an uncommon disorder of unknown etiology that is characterized by an invasive process that partially destroys the gland and extends into adjacent neck structures. Its clinical manifestation as a stonyhard, poorly defined enlargement over the thyroid gland and local compression of the trachea, esophagus and recurrent laryngeal nerve can mimic invasive thyroid carcinoma and mask the accompanied thyroid neoplasm. A case of Riedel's thyroiditis in a 59-year-old female patient, admitted with a previous diagnosis of adenomatous goiter, is reported. So, we present this case with the review of literatures.