Riedel's thyroiditis
Riedel's thyroiditis, is a chronic form of thyroiditis. It is now believed that Riedel's thyroiditis is one manifestation of a systemic disease that can affect many organ systems called IgG4-related disease. It is often a multi-organ disease affecting pancreas, liver, kidney, salivary and orbital tissues and retroperitoneum. The hallmarks of the disease are fibrosis and infiltration by IgG4 secreting plasma cells. 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 (woody) and fixed to adjacent structures. The inflammatory process infiltrates muscles and causes symptoms of tracheal compression. Surgical treatment is required to relieve tracheal or esophageal obstruction. Diagnosis. Diagnosis is done by biopsy Treatment. Therapy usually consists of prednisolone, nonetheless some cases may require surgery. Tamoxifen has been proposed as part of a treatment plan. Treatment is directed to surgical relief of compressive symptoms. Tamoxifen may also be beneficial. The type of surgery which is indicated here is isthmectomy. 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 commonly seen in women. Eponym. It is named for Bernhard Riedel. He first recognized the disease In 1883 and published its description in 1896.