The types of thyroiditis that can cause abnormalities of surgical significance are which of the following?

a. Chronic lymphocytic thyroiditis (Hashimoto disease)

b. Riedel struma

d. Granulomatous (subacute) thyroiditis

There are three types of thyroiditis that can cause thyroid abnormalities of surgical significance. The most common is chronic lymphocytic (Hashimoto) thyroiditis, an autoimmune disease that can occur in any age group. Occasionally, Hashimoto disease causes unilateral thyroid enlargement that simulates malignancy. The rarest form of thyroiditis is Riedel struma which can mimic a diffuse thyroid carcinoma because of the fibrotic infiltrative process that results. Hashimoto thyroiditis is associated with reduced functional capacity of the thyroid which increases TSH secretion, and a goiter develops. Because of the associated fibrosis, a nodular goiter or neoplasm is suggested. Thyroidectomy may be indicated for treatment of a solitary nodule, particularly if it is cold, suspicious, definitely malignant or solid, and fine needle aspirate is indeterminate. Granulomatous, DeQuervain, and subacute thyroiditis are terms that refer to a disease that usually occurs in young women within weeks of an upper respiratory or other viral infection. The disease is usually self-limited, but may persist for several months longer. In unusual patients, the disease may be confined to one lobe and result in a firm, slightly tender mass suggesting carcinoma. Lobectomy may be indicated to rule out the presence of malignancy. Total thyroidectomy may be considered for persistent, painful thyroiditis after months of steroid therapy have failed.

Goiter with a woody or fibrous component involving the adjacent strap muscles and carotid sheaths is referred to as Riedel struma. It is rare and the cause is not known. It is associated with other types of fibrotic processes including retroperitoneal fibrosis, sclerosing cholangitis, and fibrosing mediastinitis. Although considered self-limited, the process may be associated with considerable morbidity as a result of localized pain and compression of adjacent structures such as the airway. Occasionally, tracheostomy is required. Airway compression may also require open biopsy resection of the isthmus with as much as the fibrosis as possible without endangering the recurrent laryngeal nerves.