Monday, 13 February 2012

When Sarcoidosis Targets the Thyroid Gland

Elaine Moore
In progressive hypothyroidism or in cases of hyperthyroidism that's resistant to treatment, an evaluation for sarcoidosis is indicated.
Sarcoidosis is an inflammatory granulomatous disease that may affect the thyroid gland either alone or in conjunction 
Thyroid Gland - Medline Plus Encyclopedia
Thyroid Gland
Medline Plus Encyclopedia
with other organs. In sarcoidosis, clumps of abnormal tissue composed of immune cells (non-caseating granulomas) lodge in various organs. According to lead researcher M. Giovinale at the Catholic University of the Sacred Heart in Rome, sarcoidiosis is associated with pulmonary findings in more than 90 percent of patients. However, extrapulmonary (targeting organs other than the lungs) involvement is common, and all organs can be involved (especially lymph nodes, eyes, joints, central nervous system). Sarcoidosis frequently occurs as a systemic autoimmune disorder affecting multiple organs and tissues. Giovinale also reports than an isolated extrapulmonary disease, such as sarcoidoisis of the thyroid gland with no other organ involvement, is seen in less than 10 percent of patients.

Presentation of Thyroid Sarcoidosis

Sarcoidosis of the thyroid gland is considered relatively rare. Similar to other thyroid disorders, thyroid sarcoidosis is most likely to affect affect young and middle-aged females. However both males and females of all ages may be affected. This condition primarily causes hypothyroidism because of the development of fibrosis (scar tissue). However, it may cause a euthyroid (normal thyroid function) form of thyroiditis or multinodular goiter along with thyroid gland enlargement (goiter). In multinodular goiter, patients may experience shortness of breath when lying in a supine position.

On occasion, sarcoidosis of the thyroid gland occurs in conditions of hyperthyroidism, primarily in Graves’ disease and less often in conditions of toxic multinodular goiter (TMG). In TMG toxic refers to the development of hyperthyroidism. When sarcoidosis occurs in patients with hyperthyroidism that's resistant to treatment with I131 ablation or anti-thyroid drugs, an evaluation for sarcoidosis is indicated. In cases where thyroidectomy surgery was used to treat hyperthyroidism that didn't respond well to other treatments, sarcoidosis of the thyroid gland has been reported as an incidental finding in postoperative tissue studies.


On imaging scans (RAI-uptake and scan) granulomas may easily be identified as cold thyroid nodules. On occasion these lesions are mistaken for thyroid cancer. Patients with conditions of systemic sarcoidosis without any evidence of thyroid disease may also develop sarcoid lesions in various organs including the thyroid gland.

The Immune System in Sarcoidosis

T-cell lymphocyte activation is an underlying feature of sarcoidosis. According to Dr. M.C. Rodriguez, sarcoidosis is suspected of developing as an inflammatory response to one or more environmental triggers. This trigger can be another disorder that stimulates the immune system such as an infection or hypersensitivity reaction. Sarcoidosis can also be triggered by the use of interferon compounds in hepatitis C and other disorders.

Sarcoidosis can also occur in conjunction with various autoimmune disorders. Like many autoimmune disorders, thyroid sarcoidosis shows a favorable response to corticosteroids. However, effects subside when the medication is stopped, making surgery a better treatment option.

Symptoms and Signs of Thyroid Sarcoidosis

Patients with thyroid sarcoidosis may show signs of thyroid dysfunction related to a primary thyroid disorder such as Graves' disease or they may have normal thyroid function. Often, symptoms related to sarcoidosis such as pulmonary changes or skin lesions are the first indications of thyroid sarcoidosis.

The granulomas of sarcoidosis, which can be confused with multiple nodules upon palpitation of the thyroid gland, can cause elevated levels of both circulating 25 OH Vitamin D and also 1, 25 OH vitamin D. Excess vitamin D may contribute to conditions of both hypoparathyroidism and hyperparathyroidism, which, in turn, can cause imbalances in calcium metabolism.

Other laboratory changes that may occur in sarcoidosis include a low white blood cell count, elevated urine and plasma calcium levels, and a low uric acid level.

Similar to but distinct from Graves’ ophthalmopathy, sarcoidosis may affect the eye and cause symptoms of proptosis and orbital swelling that may be confused with euthyroid Graves’ disease or Graves’ ophthalmopathy. Sarcoidosis affecting the eye may also be confused with the periorbital edema frequently seen in hypothyroidism.

Sources:

Giovinale M, Fonnesu C, Soriano A, Cerquaglia C, Curigliano V, Verrecchia E, De Socio G, Gasbarrini G, Manna R. 2009. “Atypical Sarcoidiosis: Case Reports and Review of the Literature,” European Review of Medical Pharmacology and Science. Mar;13 Suppl 1:37-44.
Rodriguez MC, Rani D and Faas H. 2007.“Unusual clinical course of Graves’ thyrotoxicosis and concomitant sarcoidosis: case report and review of literature,” Endocrine Practice, Mar-Apr; 13(2); 159-163.
Zimmerman-Besling T, Christensen L, Hansen HS, et al, 2000.“A case of sarcoidosis and sarcoid granuloma, papillary carcinoma, and Graves’ disease in the thyroid gland,” Thyroid, Mar; 10(3): 275-278.
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