An<unk> , more commonly known as a canker sore, is a painful, open sore in the mouth. Canker sores are white or yellow and surrounded by a bright red area. They are benign (not cancer) and usually appear on the inner surface of the cheeks and lips, tongue, soft palate, and the base of the gums.
Aphthous ulcer
Buruli ulcer
Stasis ulcer
Venous ulcer
Tropical ulcer
Angina bullosa haemorrhagica
Genital ulcer
Hunner's ulcer