The etiology of Graves disease is unknown. The incidence has a 10 to 1 preponderance of females in the United States. Grossly, the thyroid is enlarged 1 to 2 fold. On cross section it appears fleshy, soft and extremely hyperemic. 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.