Riedel Thyroiditis Treatment & Management

The rarity of Riedel thyroiditis (RT) makes controlled studies of RT therapy impractical. Recommendations for medical treatment have been largely based on empirical experience. Pharmacologic therapy includes the use of corticosteroids, tamoxifen, and levothyroxine.

Surgery for patients with RT serves the dual purpose of establishing the diagnosis and relieving tracheal compression. A wedge resection of the thyroid isthmus remains the preferred method for accomplishing these ends. Surgery is indicated when tissue is needed for diagnosis, medical treatment shows no benefit, or compressive symptoms are very severe.^[15]

The patient with RT should be followed for progression of the disease and for the development of multifocal fibrosclerosis. Repeat imaging of the neck by CT scanning or MRI should be performed at intervals defined by the rate of progression.

The patient's thyroid-stimulating hormone (TSH) level should be routinely checked and maintained in the reference range, with levothyroxine administered as necessary.^[16]

An endocrinologist should be consulted in the management of RT. Surgical consultation is necessary for a diagnostic open biopsy.

Currently, corticosteroid therapy is the medical treatment of choice for patients with Riedel thyroiditis (RT).^[17] Corticosteroids are believed to act by reducing inflammation and by inhibiting the actions of fibrinogenic cytokines. Most studies note a reduction in goiter size and the relief of local compressive symptoms, although some patients show no benefit.

Some investigators believe that a favorable response is more likely early in the course of the disease. Improvement is less likely to occur in patients with advanced RT when the affected portions of the thyroid gland have been completely replaced by fibrotic tissue.

No consensus has been reached on the corticosteroid dosing regimen. However, all studies advocate an initially high dose to alleviate compressive symptoms, followed by gradual tapering over months to a lower, maintenance dose.

The effectiveness of therapy can be judged by symptomatic improvement and by following the reduction of the ESR and the thyroid autoantibody levels. Many patients can be weaned from therapy, but others require more prolonged treatment.

Tamoxifen has been used in patients with Riedel thyroiditis (RT) as a first-line therapy, but it has also been employed after the failure of corticosteroid treatment. The usual dose that has been found to be effective is 20mg taken orally twice daily.^[8] Patients who respond can be tapered to 20mg once each day or to 10mg twice daily. Because of the relatively infrequent occurrence of RT, comparison studies with tamoxifen and steroid therapy have not been undertaken.

Few and colleagues advocated tamoxifen use in a study of 4 patients with progressive RT who were not responsive to corticosteroids or surgical decompression.^[18] Each patient had a decrease of 50% or more in the size of the thyroid mass, with 1 patient having total resolution. Since then, additional reports have described successful treatment of RT with tamoxifen.^{[19, 20, 21]}

An oral dose of 20mg twice daily provided each patient with symptomatic improvement, as well as a reduction in the size of the involved tissue as measured on CT scan.

Estrogen receptors have not been demonstrated in RT tissue. Therefore, the mechanism of action was not proposed to be tamoxifen's antiestrogen activity but rather its induction of transforming growth factor beta, a potent inhibitor of fibroblast proliferation.^[18]

Mycophenolate (Cell-Cept) is an immunosuppressive therapy often used to prevent rejection after transplantation and/or in graft versus host disease. It has been used in disorders characterized by systemic fibrosis. In one study, significant improvement was noted after 90 days when used in combination with prednisone.^[22]

Use levothyroxine therapy to correct hypothyroidism associated with Riedel thyroiditis (RT).^[16] Many authorities advocate not only thyroid replacement but also suppression of TSH in all patients with RT, regardless of thyroid function. However, the degree to which TSH stimulates the fibroinflammatory processes of RT, if at all, is unknown. Consequently, recommendations for TSH suppression must be regarded as empirical.

Open surgical biopsy is essential for definitively establishing a diagnosis of Riedel thyroiditis (RT) and for excluding carcinoma.

A wedge resection of the isthmus relieves tracheal compression. Grossly, the affected tissue is stony and hard and is white or pale gray. It has a similar feel to cartilage when incised.

More extensive thyroid surgery is generally discouraged because extrathyroid fibrosclerosis alters the anatomy and obliterates surgical planes. The trachea, esophagus, carotids, recurrent laryngeal nerves, or parathyroid glands may be encased by fibrotic tissue and are at increased risk for iatrogenic surgical damage.^[3]