Oral melanoacanthoma and oral melanotic macule: a report of 8 cases, review of the literature, and immunohistochemical analysis 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 Melanocytic Tumors Transformation of a benign oral pigmentation to primary oral melanoma Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology and Endodontics