Simultaneous Occurrence of Melanotic Macule and Melanoma in the Oral Cavity: A Case Report

Received September 7, 2020 Revised September 14, 2020 Accepted September 15, 2020 While oral melanotic macule is regarded as the most frequent oral pigmented lesion without any harmful symptom, oral melanoma is a very rare and life-threatening disease among oral pigmented lesions. Oral melanotic macule has previously been described as benign, with no malignant potential. However, a few case reports have raised the question of malignant potential of oral melanotic macule. In this case report, we present a case of coexistence of oral melanotic macule and oral melanoma. A 66-year-old man with a chief complaint of black pigmentation on gingiva showed the lesion spread out on the right palatal gingiva, the right maxillary buccal gingiva and the right buccal mucosa, appearing to merge with one another. Biopsies were performed on the right palatal gingiva and the right buccal mucosa. While the lesion on the right palatal gingiva was diagnosed as an oral melanotic macule, the other lesion on the right buccal mucosa was diagnosed as an oral melanoma. The present case implied the possibility of malignant potential of oral melanotic macule. Therefore, oral melanotic macule needs careful periodic observation for early detection and prompt treatment of the transformed oral melanoma.