Riedel's thyroiditis

Riedel's thyroiditis, also called Riedel's struma is a chronic form of thyroiditis.

Pathophysiology
Riedel's thyroiditis is characterized by a replacement of the normal thyroid parenchyma by a dense fibrosis that invades adjacent structures of the neck and extends beyond the thyroid capsule. This makes the thyroid gland stone-hard and fixed to adjacent structures.

A shared mechanism with retroperitoneal fibrosis and sclerosing cholangitis has been suggested.

Prevalence
Riedel's thyroiditis is classified as rare. Most patients remain euthyroid, but approximately 30% of patients become hypothyroid and very few patients are hyperthyroid. It is most seen in women.

Treatment
Tamoxifen has been proposed as part of a treatment plan.

Eponym
It is named for Bernhard Riedel. He first recognized the disease In 1883 and published its description in 1896.