Oral Melanotic Macule: Symptoms and Treatment Skinsight Pigmented macular lip lesion Clinical Advisor ORAL MELANOTIC MACULE (OMM) (Also called focal melanosis labial melanotic macule) A benign, localized, flat pigmented lesion of the oral mucosa Caused by a focal increase in melanin production Metastatic oral malignant melanoma transformed from pre existing pigmented lesions in mandibular gingiva: Report of an unusual case ScienceDirect