Melanocytic hyperplasia of the oral mucosa. Lesions that exhibit melanocytic hyperplasia are uncommon in the oral mucosa. They are even more rare than the various morphologic types of nevomelanocytic lesions. This article reports the clinicopathologic features of oral lesions diagnosed as lentigo simplex, junctional lentigo ("jentigo"), atypical melanocytic hyperplasia (melanoma in situ), and melanocanthoma. The proper terminology for these lesions is also discussed. 