Iris Melanosis in Cats: Causes, Symptoms, and Treatment Cats.com New Research Helps Identify Uveal Melanomas Most Likely to Spread to the Liver Melanoma (for Teens) Nemours KidsHealth 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 Melanotic Neuroectodermal Tumor of Infancy MD Searchlight Melanocytic Nevi MD Searchlight