These borders are not elevated or irregular in the acute form of peptic ulcer, and regular but with elevated borders and inflammatory surrounding in the chronic form. In the ulcerative form of gastric cancer, the borders are irregular. Surrounding mucosa may present radial folds, as a consequence of the parietal scarring. Microscopic appearance
A gastric peptic ulcer is a mucosal perforation that penetrates the muscularis mucosae and lamina propria, usually produced by acid-pepsin aggression. Ulcer margins are perpendicular and present chronic gastritis. During the active phase, the base of the ulcer shows 4 zones: fibrinoid necrosis, inflammatory exudate, granulation tissue and fibrous tissue. The fibrous base of the ulcer may contain vessels with thickened wall or with thrombosis. Differential diagnosis
Conditions that may appear similar include:

Prevention
Prevention of peptic ulcer disease for those who are taking NSAIDs (with low cardiovascular risk) can be achieved by adding a proton pump inhibitor (PPI), an H2 antagonist, or misoprostol. NSAIDs of the COX-2 inhibitors type may reduce the rate of ulcers when compared to non-selective NSAIDs. PPI is the most popular agent in peptic ulcer prevention. However, there is no evidence that H2 antagonists can prevent stomach bleeding for those taking NSAIDs. Although misoprostol is effective in preventing peptic ulcer, its properties of promoting abortion and causing gastrointestinal distress limit its use. For those with high cardiovascular risk, naproxen with PPI can be a useful choice. Otherwise, low-dose aspirin, celecoxib, and PPI can also be used.
Erosion of the gastrointestinal wall by the ulcer leads to spillage of the stomach or intestinal contents into the abdominal cavity, leading to an acute chemical peritonitis. The first sign is often sudden intense abdominal pain, as seen in Valentinos syndrome. Posterior gastric wall perforation may lead to bleeding due to the involvement of gastroduodenal artery that lies posterior to the first part of the duodenum. The death rate in this case is 20%. Penetration is a form of perforation in which the hole leads to and the ulcer continues into adjacent organs such as the liver and pancreas. Gastric outlet obstruction (stenosis) is a narrowing of the pyloric canal by scarring and swelling of the gastric antrum and duodenum due to peptic ulcers. The person often presents with severe vomiting. Cancer is included in the differential diagnosis (elucidated by biopsy), Helicobacter pylori as the etiological factor making it 3 to 6 times more likely to develop stomach cancer from the ulcer. The risk for developing gastrointestinal cancer also appears to be slightly higher with gastric ulcers

Cause
H. pylori
Helicobacter pylori is one of the major causative factors of peptic ulcer disease. It secretes urease to create an alkaline environment, which is suitable for its survival. It expresses blood group antigen adhesin (BabA) and outer inflammatory protein adhesin (OipA), which enables it to attach to the gastric epithelium. The bacterium also expresses virulence factors such as CagA and PicB, which cause stomach mucosal inflammation.