thyroiditis /thī′roidī″tis/ , inflammation of the thyroid gland. Acute thyroiditis caused by staphylococcal, streptococcal, or other infections is characterized by suppuration and abscess formation and may progress to subacute diffuse disease of the gland. Subacute thyroiditis is marked by fever, weakness, sore throat, and a painfully enlarged gland containing granulomas composed of colloid masses surrounded by giant cells and mononuclear cells. Chronic lymphocytic thyroiditis (Hashimoto’s disease), characterized by lymphocyte and plasma cell infiltration of the gland and diffuse enlargement, seems to be transmitted as a dominant trait, may be associated with various autoimmune disorders, and is more common in women. Another chronic form of autoimmune thyroiditis is Riedel’s struma, a rare progressive fibrosis, usually of one lobe of the gland but sometimes involving both lobes, the trachea, and surrounding muscles, nerves, and blood vessels. Radiation thyroiditis occasionally occurs 7 to 10 days after the treatment of hyperthyroidism with radioactive iodine 131.
