Meckel diverticulum is an anomaly seen in about 2% of the population with a slight male predominance. It is persistent proximal portion of the vitelline duct. Other congenital anomalies may coexist. Location is approximately 80 cm proximal to the ileo-cecal valve on the outer mesenteric border. It is usually lined by small intestinal mucosa but may also contain gastric, duodenal, colonic or pancreatic tissue. The image shows gastric mucosa forming a polypoid mass in a Meckel diverticulum. Image courtesy of Dr. Jean-Christophe Fournet, Paris, France; humpath.com.