Mucosal melanocytic macules Pigmented Oral Lesions: Clues to Identifying the Potentially Malignant Consultant360 Brown spots, especially on the lips, can be alarming to some. In some instances it can indicate rare oral mucosal melanoma, however in this case it was a non cancerous labial melanotic macule. Differential Diagnosis of Pigmented Lesions in the Oral Mucosa: A Clinical Based Overview and Narrative Review Diagnosis of oral pigmentations and malignant transformations ScienceDirect