Morphological and immunohistochemical features of the canine gastric polyps. (A) Gross aspect; (B) Hyperplastic polyp; (C) Inflammatory polyp; (D) (E) H. pylori immunoexpression. (F) COX-2 immunoexpression; (G) Ki-67 immunoexpression; (H) p53 immunoexpression. Inset: intratubular seminoma (+control) (I) CDX2 immunoexpression. Inset: normal intestine (+control). Morphological and immunohistochemical features of the canine gastric polyps. (A) Gross aspect of the pyloric gastric mucosa showing a solitary polyp (delimited area) (case 9); (B) and (C) Microscopic examination of haematoxylin and eosin-stained slides revealing a hyperplastic polyp (case 4) and an inflammatory polyp (case 8). Bar = 500 μm and 100 μm, respectively. (D) Photomicrograph demonstrating the positive H. pylori expression in a hyperplastic polyp (case 2). Bar = 200 μm. (E) Detail of the previous case highlighting the large amount of Helicobacter spp. organisms inside the gastric glands. Bar = 10 μm. (F) Photomicrograph revealing strong and diffuse COX-2 expression into branched foveolar epithelium of the hyperplastic polyp (case 1). Bar = 200 μm. Inset presenting a detail of the COX-2 expression into foveolar epithelium; (G) Immunostaining of Ki-67 in the hyperplastic epithelium (case 3: 32.1%). Bar = 200 μm. Inset showing the detail of KI-67 expression in the isthmus and in the glands base. (H) Photomicrograph revealing a negative immunohistochemical reactivity of p53 in the hyperplastic polyp (case 2). Bar = 200 μm. Tissue from canine intratubular seminoma has been used as positive control for p53 (inset). (I) Negative CDX2 expression in the hyperplastic polyp (case 1). Bar = 200 μm. Tissue from canine normal intestine has been used as positive control for CDX2 (inset). Immunoperoxidase-diaminobenzidine stain with Mayer's haematoxylin counterstain (D-I).