Does anyone know what this black mark on my lip is? Started last August so it's I've had it nearly a year, was living in Spain at the time for 6 months Differential Diagnosis of Pigmented Lesions in the Oral Mucosa: A Clinical Based Overview and Narrative Review Melanotic macule. Benign. Dark spot on labia (or lip). Analogous to lentigo simplex. Hyperpigmented basal keratinocytes & dermal melanophages. Slight in single basal melanocytes; NO nests. More info like this in Mystery behind labial and oral melanotic macules: Clinical, dermoscopic and pathological aspects of Laugier Hunziker syndrome