In the Chicago Tribune, Doctor Allen J. Douma explains that while the terms "stomach lesion" and "stomach ulcer" are used interchangeably, they are not synonymous. According to Dr. Douma, ulcers are a type of lesion. Medically, lesions are defined broadly, and include body parts that are broken or in which function has been impaired. By contrast, ulcers are localized breaks in organ tissue that feature necrotic tissue.
Although the stomach is usually well protected from the stomach acid it holds by a layer of protective mucus, sometimes this mucus layer breaks down. When this occurs, the stomach acid can erode portions of the stomach lining -- an ulcer, according to the Chicago Tribune. Two circumstances can lead to this problem. In some cases, the amount or concentration of stomach acid increases and overcomes the protective strength of the mucus. In other cases, too little mucus is produced, leaving the lining vulnerable.
According to the Chicago Tribune, stomach ulcers and lesions are not as commonly diagnosed as are duodenal ulcers, which occur in the small intestine. Stomach ulcers generally occur in people between 55 and 70 years of age. Often, non-steroidal anti-inflammatory drugs are implicated as the cause behind some stomach lesions.