Ch22: Pigmentations of the Oral Mucosa and Facial Skin 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. Metastatic oral malignant melanoma transformed from pre existing pigmented lesions in mandibular gingiva: Report of an unusual case ScienceDirect Malignant melanomacutaneous and mucosal. a, b Melanoma of the right Download Scientific Diagram