Labial Macules: Dark Spots on the Lip Dermatology 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 Oral melanotic macule and primary oral malignant melanoma: Epidemiology, location involved, and clinical implications Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology and Endodontics Diagnosis of oral pigmentations and malignant transformations ScienceDirect