Melanotic macules and melanoacanthomas of the lip. A comparative study with census of the basal melanocyte population.

Fifteen labial melanotic macules and three melanoacanthomas of the lip were studied with particular regard to their distinguishing histopathological features including a quantitative study of the basal melanocyte population. Both of these entities show an increased population of melanocytes arranged as single units along the junctional zone. These conditions differ from each other primarily by the presence of intraepithelial melanocytes in melanoacanthoma. In our opinion, the melanotic macule of the lip has numerous histological counterparts that occur on other mucosal and cutaneous surfaces. Oral mucosal analogies to the labial melanoacanthoma also exist.