Graves' Disease

Graves’ disease is an autoimmune disorder in which there is a production of IgG antibodies called thyroid-stimulating immunoglobulin (TSI) directed to TSH receptor which will result in continuous and excessive stimulation of thyroid hormone production and secretion. The symptoms of Graves' disease is typical of thytoxicosis with exopthalmos and pretibial myxedema. Graves' disease affects women more than me up to 10 times. 

 Normal Thyroid

Legends:

1. Follicles with colloid inside 
2. Parafollicular cells or C cells
3. Vein

This is the normal thyroid histology. We can see that thyroid is actually composed of many follicles lined by cuboidal epithelium or low columnar epithelium. When the follicles are actively secreting T3 and T4, the epithelium becomes columnar. The follicles are filled with pink colloid rich in thyroglobulin. We can see that between the follicles, there are some parafollicular cells or C cells. These cells secrete Calcitonin, a hormone that counteract parathyroid hormone (lowering blood Ca²⁺). 

One can see that the epithelium cells lined perfectly with the colloid substance. The black line in the picture represent the attached border of epithelium with the colloid.

Graves' Disease

At first glance, one might not notice any abnormalities in graves' disease. Closer inspection reveals A: cytoplasmic bulging of epithelium cells into the colloid and B: appearance of vacuoles at the edge of the colloids. This "scalloping" causes the border between epithelium cells and colloid not as smooth as in the normal thyroid. All of these findings are caused by increased hormone secretion due to stimulation of TSH receptor. Below is a beautiful picture with more prominent scalloping and cytoplasmic bulging.