Premalignant or precancerous (also referred to as “potentially malignant”) oral lesions involve the skin lining of the mouth (known as the epithelium) and may be at risk for becoming (transforming into) an oral cancer, although it is difficult to predict which lesions will transform and how long it will take. The disease is Experimental Factor Ontology identifier EFO_0006566 (dysplastic oral keratinocyte). Also known as: oral cavity dysplasia, oral epithelial dysplasia, premalignant oral lesion, premalignant oral lesions.