Excess acid inside the stomach, the bacterium called H. pylori, or painkillers taken for rheumatism can produce appearances like irritation; this is called erosion. Sometimes, as can be seen in the picture, this erosion can also be linear — running lengthways, like the ridges on the rind of a watermelon.
Sources
- Prof. Ali Tüzün İnce, MD — Kadıköy Endoscopy Center archive