Fig. 7.

UBB: a Densely cellular and somewhat ill-defined focus within the thyroid of an elderly gentleman with multiple follicular thyroid parenchymal lesions (HE, 40X). b High magnification view shows tightly packed oval cells with some nuclear overlapping, smooth chromatin, and nuclear grooves characteristic of the UBB epithelium. These cells demonstrate cytomorphology reminiscent of Walthard cell nests (see text) (HE, 600X). c UBBs showing diffuse expression of p63 and TTF-1 d (p63, 200X, TTF-1, 200X)