Erythroplakia is a much more ominous predictor of cancer than leukoplakia. A person with any red area in the mouth should see a doctor or dentist. An ulcer is a hole that forms in the lining of the mouth when the top layer of cells breaks down, and the underlying tissue shows through. An ulcer appears white because of the dead cells inside the hole. Other causes are canker sores and irritating substances, such as an aspirin, held against the gums.
Noncancerous ulcers are invariably painful.
An ulcer that doesn't hurt and lasts more than 10 days may be precancerous or cancerous and should be examined by a doctor or dentist. A person who chews tobacco or uses snuff may develop white, ridged bumps on the insides of the cheeks. These bumps can develop into verrucous carcinoma. If such a lump isn't caused by a periodontal abscess or abscessed tooth, it may be a noncancerous growth caused by irritation. Noncancerous growths are relatively common and, if necessary, can be easily removed by surgery.