Dark pigmentation in the oral cavity Clinical Advisor Oral melatonic macule or melanoma : r askdentists Pigmented lesions of the oral mucosa and perioral tissues: a flow chart for the diagnosis and some recommendations for the management ScienceDirect 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.