[Inflammatory diseases of the thyroid gland. Epidemiology, symptoms and morphology]

Inflammation of the thyroid gland makes up approximately 20% of all thyroid diseases. According to the clinical course, thyroiditis has been subdivided into acute, subacute, and chronic forms. Recent classifications are based on the fact that the majority of thyroiditis cases have an autoimmune background. The most common form of this disease is autoimmune thyroiditis (AIT), with or without subclinical/manifest hypothyroidism; less common forms of autoimmune thyroiditis comprise subacute granulomatous (de Quervain's) thyroiditis, postpartum thyroiditis, silent ("painless") thyroiditis, and invasive-sclerosing thyroiditis (Riedel's thyroiditis). Non-autoimmune thyroiditis is very rare (acute suppurative thyroiditis, radiation thyroiditis). Thyroiditis is both clinically and morphologically an important differential diagnosis of thyroid tumours. The present paper deals with the epidemiology, clinical course, and morphology of thyroiditis, knowledge of which is essential for the examination of cytological and histological thyroid specimens.