In 1896 Riedel1 described a disease of the thyroid gland characterized by subacute, progressive swelling and hardening of the gland and progressive difficulty in respiration. Since that time many cases of benign swelling of the thyroid gland have been reported under the name of Riedel's struma, woody thyroiditis, ligneous thyroiditis or chronic thyroiditis. In 1912 Hashimoto2 reported 4 cases in which the subjective symptoms and physical findings were similar to those reported by Riedel but in which the thyroid tissue was replaced by lymphoid tissue. He called this condition struma lymphomatosa. The symptoms of the two conditions are much alike, and cases which are similar to those reported by Hashimoto are frequently reported under the name Riedel's struma. In 1931 Graham3 analyzed the cases reported prior to that time. He found reports of 104 cases. Of these, he classified 41 as definite instances of Riedel's struma and