Melanoma Signs & Symptoms Moffitt Medium sized congenital melanocytic nevus spontaneously lightening in a pediatric patient and management JAAD Case Reports PDF] Morphologic changes of acquired melanocytic nevi with eccentric foci of hyperpigmentation ("Bolognia sign") assessed by dermoscopy. Semantic Scholar 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