Figure 2. . Representative hematoxylin and eosin-stained sections and immunohistochemical stains showing neural differentiation in the neck tumor.

(A) Low-magnification view of tumor showing papillary configurations and ribbons of multilayered tumor cells. An area of necrosis is present in the lower right (hematoxylin and eosin [H&E], 40×). (B) Higher magnification view showing rosettes and more solid regions (H&E, 200x). (C) High-magnification view showing clusters of cells with larger nuclei displaying smooth feathery vesicular chromatin and small nucleoli (arrows) adjacent to the ribbons of pseudostratified tumor cells with smaller nuclei having more condensed (hyperchromatic) chromatin (H&E, 400x). (D) Widespread cytoplasmic staining of cells with nestin between trabeculae and more prominently around basally oriented cells of trabeculae and papillary fronds (Nestin, 200×). (E) Focal staining for CD56 (CD56, 200×). (F) Scattered cells show nuclear and cytoplasmic staining for neuroblast and neuroendocrine marker PGP9.5 (PGP9.5, 400×).