Inflammation of the thyroid gland occurs as autoimmune thyroiditis (long-term inflammatory disease), postpartum thyroiditis, subacute granulomatous thyroiditis (self-limiting inflammation), Riedel’s thyroiditis (rare, invasive fibrotic process), and miscellaneous thyroiditis (acute suppurative, chronic infective, and chronic noninfective). Thyroiditis is more common in women than in men.
Autoimmune thyroiditis is due to antibodies to thyroid antigens. It may cause inflammation and lymphocytic infiltration (Hashimoto’s thyroiditis). Glandular atrophy and Graves’ disease are linked to autoimmune thyroiditis.
Postpartum thyroiditis (silent thyroiditis) is another form of autoimmune thyroiditis that occurs in women within 1 year after delivery.
Subacute granulomatous thyroiditis usually follows mumps, influenza, coxsackievirus, or adenovirus infection. Riedel’s thyroiditis is a rare condition of unknown etiology.
Miscellaneous thyroiditis results from bacterial invasion of the gland in acute suppurative thyroiditis; tuberculosis, syphilis, actinomycosis, or other infectious agents in the chronic infective form; and sarcoidosis and amyloidosis in chronic noninfective thyroiditis.