Fig. 3

Special and immunohistochemical stains. a Periodic acid–Schiff with diastase digestion (4x): diffusely and strongly positive in tumor cells and secretion. b Lysozyme (4x): diffusely and strongly positive in tumor cells and secretion. c Chromogranin (10x): highlighted residual normal neuroendocrine cells. d Ki67 (10x): approximately 40% tumor cells in the poorly-differentiated area (upper half) were positive and only rare positivity was detected in the well-differentiated area (lower half). e beta- catenin (4x) (inset: high magnification (40x) of beta-catenin): membranous stain in all the tumor cells regardless of differentiation. f Her-2/neu (4x) (inset: high magnification (40x) of Her-2/neu in the poorly-differentiated area): nuclear and cytoplasmic stain in the poorly-differentiated area and absence of stain in the well-differentiated area