About Riedel’s Thyroiditis
Riedel’s thyroiditis is a very rare condition with an unknown cause. In 1883, Professor Bernhard Riedel first recognized the disease. He published a description of 2 cases in 1896 and of a third case in 1897. Riedel used the term ‘eisenharte struma’ to describe the stone-hard consistency of the thyroid gland and its fixation to adjacent structures. He noted the presence of chronic inflammation with fibrosis and the absence of malignancy on microscopic examination. It is believed to be an autoimmune condition, where the immune system attacks normal tissue. It is sometimes called Riedel’s struma or invasive fibrous thyroiditis. Riedel’s thyroiditis is more common in women than in men, and generally affects people between the ages of 30 and 60.
Signs and Symptoms
Patients with Riedel’s thyroiditis have a painless mass in the front of their neck which is hard and “woody” to touch. As the disease progresses, symptoms develop. The main issue is that the fibrotic thyroid gland compresses the oesophagus and the trachea. This compression produces the following symptoms:
- Difficulty swallowing (dysphagia)
- Shortness of breath (dyspnoea)
Eventually, as the normal thyroid tissue is replaced by fibrous scar tissue, there is insufficient functioning tissue available to produce adequate levels of thyroid hormones, resulting in hypothyroidism. Patients with Riedel’s thyroiditis may also suffer hypoparathyroidism.
The cause of Riedel’s thyroiditis is unclear and widely debated. It is believed to be a form of autoimmune thyroiditis. The two main theories are that it is an autoimmune disorder or a primary fibrotic disorder. Riedel’s thyroiditis can occur in people who have other autoimmune diseases. The disorder also exhibits a good response to steroid therapy, like many other autoimmune disorders. Histologically, specimens taken from patients with Riedel’s thyroiditis show hallmarks of autoimmune infiltration – lymphocytes, histiocytes, vasculitis and plasma cells. In addition, a significant proportion of patients with Riedel’s thyroiditis have anti-thyroid antibodies. However, Riedel’s thyroiditis may be a primary fibrotic disorder. Riedel’s thyroiditis is also associated with other fibrotic disorders, including sclerosing cholangitis, retroperitoneal fibrosis, periorbital fibrosis, mediastinal fibrosis, and retro-orbital fibrosis. The most recent theory surrounding the aetiology of Riedel’s thyroiditis is that it is an IgG4-RD (immunoglobulin G4 related disease). IgG4-RD is a condition where inflammatory cells produce fibrosis in one or more organs. The IgG4 antibody may be raised in the blood and may be present in tissue samples of people with Riedel’s thyroiditis. Others believe it is a variant of Hashimoto’s thyroiditis.
- De Quervain Thyroiditis
- Hashimoto Thyroiditis
- Thyroid Lymphoma
- Anaplastic Thyroid Carcinoma
- Subacute Thyroiditis
Because of the encroachment beyond the thyroid capsule, non-thyroid problems can be associated with Reidel’s Thyroiditis. Complications of Riedel thyroiditis can include the following:
- Airway obstruction
- Hoarseness – Due to recurrent laryngeal involvement
- Stridor – Due to tracheal compression
Associated Clinical Features
Approximately one third of patients with Reidel’s Thyroiditis have an associated manifestation of multifocal fibrosclerosis in other parts of the body.
These manifestations can include the following:
- Retroperitoneal fibrosis
- Mediastinal fibrosis
- Orbital pseudotumor
- Pulmonary fibrosis
- Sclerosing cholangitis
- Lacrimal gland fibrosis
- Fibrosing parotitis
A tissue sample is needed to diagnose Riedel’s thyroiditis. This is usually performed via a surgical biopsy of the affected tissue because a diagnosis cannot be made based on fine needle biopsy. The fibrotic changes and the paucity of thyroid follicular cells usually result in a non-diagnostic fine-needle aspiration biopsy.
On formal histopathology, a sample will show thick, widespread fibrosis that destroys the normal structure of the thyroid gland. In some instances, the scarring and fibrosis extends beyond the capsule of the thyroid gland. It is important to obtain a biopsy, as Riedel’s thyroiditis presents in a similar fashion to carcinoma of the thyroid gland, and it is important to rule out carcinoma as a cause of the patient’s symptoms.
Riedel’s Thyroiditis Treatment
Therapy usually consists of prednisone. Tamoxifen has been proposed as part of a treatment plan. Nonetheless some patients may require surgery.
Treatment is directed to surgical relief of compressive symptoms. Pharmacological therapies are also useful in the treatment of Riedel’s thyroiditis. As aforementioned, some patients exhibit a very good response to corticosteroid therapy. Another treatment which has shown to benefit Riedel’s thyroiditis patients is tamoxifen, a treatment which is also used in breast cancer patients because it blocks the oestrogen receptor. Tamoxifen works in Riedel’s thyroiditis by blocking the proliferation of connective tissue.
Most patients remain euthyroid, but approximately 30% of patients become hypothyroid and very few patients are hyperthyroid. It is most seen in women. Patients who have become hypothyroid are treated with thyroxine to return them to a euthyroid state. Thyroxine therapy is life-long.
If you have questions or concerns about thyroid health make an appointment to see our thyroid surgeon.