Figure 3

Immunohistochemical findings of the resected specimen. Duodenal mucosa in the upper part of the polyp (A - D), with erosion (E - H), and in the lower part of the polyp (I - L) are shown in HE stain (A, E, and I), MUC5AC (B and F), MUC6 (C and G), MIB-1 (D, H and L), CDX2 (J), and MUC2 (K) immunostains. Surface epithelium in the upper part of the polyp is histologically similar to gastric foveolar epithelium and immunohistochemically positive for MUC5AC, suggesting gastric foveolar metaplasia (B), and the epithelium in the deeper portion and Brunner’s glands are positive for MUC6 (C). This area shows high MIB-1 labeling (D). The similar staining pattern is observed in the mucosa with erosion (E - H). Surface epithelium in the lower part of the polyp shows a villous structure, containing CDX2-positive nuclei (J) and MUC2-positive goblet cells (K), suggesting preservation of the intestinal nature. MIB-1-positive Brunner’s glands are inconspicuous in this area (L). All images are 40× magnification.