Medical Care
The rarity of Riedel thyroiditis (RT) makes controlled studies of therapy impractical. Recommendations for medical treatment have been largely based on empirical experience.
Currently, corticosteroid therapy is the medical treatment of choice for patients with RT.
Most studies note reduction of goiter size and 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 fibrosis.
Corticosteroids are believed to act both by reducing inflammation and by inhibiting the actions of fibrinogenic cytokines.
No consensus has been reached on the dosing regimen of corticosteroids. All studies advocate an initially high dose to alleviate compressive symptoms, followed by gradual tapering over months to a lower maintenance dose.
Effectiveness of therapy can be judged by symptomatic improvement and by following reduction of the ESR and thyroid autoantibody levels. Many patients can be weaned from therapy, but others require more prolonged treatment.
In many recent patients, tamoxifen has been started as primary therapy, obviating the negative consequences of steroid therapy. The usual dose found to be effective is 20 mg PO bid. Patients who respond can be tapered to 20 mg once each day or 10 mg bid. Because of the relatively infrequent occurrence of RT, comparison studies with tamoxifen and steroid therapy have not been undertaken. Few et al initially advocated tamoxifen in a study of 4 patients with progressive RT who were not responsive to corticosteroids or surgical decompression. Each of the 4 patients had a 50% or more decrease in the size of their thyroid mass, and one had total resolution.
An oral dose of 20 mg twice a day provided each patient with symptomatic improvement and a reduction in 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.
Correct hypothyroidism associated with RT with levothyroxine therapy. Many authorities advocate not only thyroid replacement but also suppression of thyroid-stimulating hormone (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. As such, recommendations for TSH suppression must be regarded as empirical.
Surgical Care
Surgery for patients with RT serves the dual purposes of establishing the diagnosis and relieving tracheal compression. A wedge resection of the thyroid isthmus remains the preferred method for accomplishing these ends.
Open surgical biopsy is essential to definitively establish the diagnosis of RT and to exclude carcinoma.
A wedge resection of the isthmus relieves tracheal compression. Grossly, the affected tissue is stony, hard, and white or pale gray in appearance. 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 in fibrosis and are at increased risk for iatrogenic surgical damage.