A, Gross appearance of a tumor with thin capsule. B, Encapsulation (arrowhead) and microfollicular growth pattern of the tumor (T) as compared with adjacent normal thyroid (N) (hematoxylin-eosin [H&E], original magnification ×100). C, Major diagnostic nuclear features including nuclear enlargement and elongation, which is best appreciated when nuclear size and shape of the tumor (T) is compared with that of adjacent normal tissue (N) (H&E, original magnification ×400). D, Irregular nuclear contours and chromatin clearing (H&E, original magnification ×400). Nuclear pseudoinclusions and nuclear grooves, as well as minor diagnostic criteria, are illustrated in eFigure 1 in the Supplement.