Mole Inside the Mouth: 5 Alarming Causes Liv Hospital Differential Diagnosis of Pigmented Lesions in the Oral Mucosa: A Clinical Based Overview and Narrative Review 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. Mucosal melanocytic macules Black Spot on Lip: What Does It Mean?