Abuse of laxatives and melanosis coli Lentigo maligna and lentigo maligna melanoma Melanotic macule. Benign. Dark spot on labia (or lip). Analogous to lentigo simplex. Hyperpigmented basal keratinocytes & dermal melanophages. Slight in single basal melanocytes; NO nests. More info like this in Oral Melanotic Macule: Symptoms and Treatment Skinsight What Is Melanonychia? What Causes It and How It's Treated Definition of melanocyte NCI Dictionary of Cancer Terms NCI