Malignant transformation of leukoplakia three times in period of 11-years--case report.

: Leukoplakia is a commonly occurring precancerous lesion. The following case report describes a patient who had multiple leukoplakia in this mouth. He had three sites of leukoplakia, the left hard palate, the gum of the right maxilla and the gum of the left mandible, all of which underwent malignant transformation during the period of 11-years after diagnosis.