Melanocytic Tumors 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 Histopathological Findings of a Melanocytic Nevus A melanocytic nevus is a benign proliferation of melanocytes. Under the microscope, typical features include: Nests or clusters of uniform melanocytes located at the dermoepidermal junction, Pathology Outlines Melanotic macule