Hashimoto's disease (autoimmune thyroiditis) is a form of chronic, painless thyroiditis that leads to goiter (thyroid enlargement) and hypothyroidism. It is most frequently found in middle aged women but can be found in either sex at any age. There is a genetic predisposition to the disease which therefore runs in families and often correlates with a particular HLA type. It appears to be an autoimmune disease resulting from the production of high titers of antibodies against thyroglobulin and an enzyme called thyroid peroxidase which is involved in the production of thyroid hormone. Although this enzyme is mostly microsomal (associated with the endoplasmic reticulum), it is also expressed on the surface of thyroid cells.  Unlike Grave's disease which results from stimulation of the thyroid to produce more hormones, the antibodies that cause Hashimoto's disease result in progressive  destruction.

One aspect of the pathology of Hashimoto's disease is the enlargement of thyroid cells which appear acidophilic in certain staining reactions. These are called Hurthle-Askanazy cells.

  Askanazy-Hurthle cells in Hashimoto's thyroiditis © Bristol Biomedical Image Archive. Used with permission

The spaces within the thyroid follicles get smaller and invasion by macrophages and  fibrosis may occur.

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