An enlargement of the thyroid gland, called a goiter, is almost always present and may appear as a cyst-like or fibrous growth in the neck.Hashimoto's thyroiditis is permanent and requires lifelong treatment.Symptoms last about 6 - 8 weeks and then resolve in most patients, although each form carries some risk for becoming chronic.Subacute thyroiditis appears to be responsible for about 10% of all cases of hypothyroidism.
Women who have had recurrent episodes after previous pregnancies and women who have other autoimmune disorders are at higher risk for this form of subacute thyroiditis. This painless condition is very similar to postpartum thyroiditis except it can occur in both men and women and at any age.Similar immune system substances called antibodies are present in both diseases, and some researchers believe that the predominance of one or another antibody determines which of the diseases become manifest.The two diseases, then, are essentially two sides of a single coin. Atrophic thyroiditis is similar to Hashimoto's thyroiditis, except a goiter is not present. Riedel's thyroiditis is a rare autoimmune disorder, in which scar tissue progresses in the thyroid until it produces a hard stony mass that suggests cancer.By the end of 5 years, about 65% of treated patients have developed hypothyroidism, after which the rate of this condition levels off to about 1% a year.Such patients need to take thyroid hormones for the rest of their lives.