Signet-ring cell carcinoma arising from a fundic gland polyp in the stomach

Figure 1 Endoscopic appearance of fundic gland polyps. A: The first polyp (0.8 cm in diameter, pedunculated, reddish, and with an erosive surface) at the mid body on the anterior wall; B: Other polyps (with a smooth surface) at the mid to high body on the greater curvature.

Figure 2 Histological findings. A: A resected specimen demonstrated signet ring cell carcinoma (between the arrows) (HE staining, × 40); B: Loosely cohesive signet ring cells from fundic oxyntic glands of fundic gland polyp infiltrate the lamina propria (HE staining, × 100).

Figure 3 Immunohistochemical findings. A: Signet ring cell carcinoma is positive for cytokeratin (arrow); B: p53 is expressed in signet ring cell carcinoma but not in the fundic oxyntic cells (arrow).