Is focal melanotic lesion potentially malignant? A case report.

Malignant melanoma is a lesion of melanocytes that is commonly observed on cutaneous surfaces. In 35-50% of cases, it originates from a pigmented precursor. Although oral melanocytic pigmentation is very common, melanocytic malignancies such as melanoma, are rare. Oral melanoma may arise from pre-existing pigmentation, but definitive precursor lesions have not been identified. Common sites for oral melanoma are the maxillary gingiva and palate. We report a case of malignant melanoma that transformed from a long-standing, focal, pigmented lesion on the mandibular gingiva and vestibular mucosa, suggesting the potentially malignant nature of focal oral melanotic lesions.