The etiology of Graves disease is unknown.
The disease is caused by the presence of circulating immunoglobulins that bind to the TSH receptor on thyroid epithelial cells and cause them to undergo both proliferation and hyperactivity.,
There is a correlation with certain HLA haplotypes (HLA-B8 and DRw3 in Caucasians and HLA-Bw46 in Chinese).
It is relatively common and between 1 and 2 % of all American woman are believed to have some level of thyrotoxicosis.
The incidence has a 10 to 1 preponderance of females in the United States.
|General Gross Description|
Grossly, the thyroid is enlarged 1 to 2 fold.
On cross section it appears fleshy, soft and extremely hyperemic.
|General Microscopic Description|
Microscopically the appearance is of intense cellularity.
Cells lining the follicles appear to be increased in number as well as in size.
The lining cells may be thrown into pseudo-papillary arrangement.
This feature must be distinguished from true papillae, which are almost always associated with malignancy.
The true papilla has a central fibrovascular core.
A pseudo-papilla is composed entirely of epithelial cells, devoid of a fibrovascular core.
Colloid, when present in the follicle stains lighter than normal.
In addition, characteristically, it presents a "scalloped" appearance.
In a normal resting acinus, the colloid is deeply staining and around its circumference is in touch with the epithelial cells.
In a "scalloped" appearance, indicative of a hyperactive lining epithelium, there are crescent shaped spaces between the epithelial cell and the margin of the colloid all the way around the circumference.
In addition to the epithelial hyperplasia and hypertrophy, there is usually an extensive infiltration by lymphoid tissue.
It is presumed that these lymphocytes are responsible from the elaboration of the antibodies that activate the thyroid.
Cotran RS, Kumar V, Robbins SL: Robbins Pathologic Basis of Disease. 5th ed. Philadelphia, W.B. Saunders, 1994, pp. 1129
Harrison's Principles of Internal Medicine, 13th Ed: Isselbach et. al. (eds). New York, McGraw-Hill, 1994, pp. 1942
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||Synopsis by: T.V.Rajan, M.D., Ph.D. (T96000D21930)