All of following are histomorphological features of Graves disease, except:

- Papillary formation which lack fibrovascular core is seen in Graves disease - Papillary formation with fibrovascular core is feature of papillary carcinoma of thyroid Graves disease: Most common cause of endogenous hypehyroidism. Caused by autoantibodies against TSH receptor that bind & stimulate thyroid follicular cells independent of endogenous trophic hormones. Thyroid gland is usually symmetrically enlarged d/t diffuse hyperophy & hyperplasia of follicular epithelial cells. Histologically, follicular epithelial cells in untreated cases are tall & more crowded than usual. This crowding often results in formation of small papillae, which project into follicular lumen & encroach on colloid, sometimes filling the follicles. Colloid within follicular lumen is pale, with scalloped margins.