Early Stage Melanoma of the Vermillion with Mucosal Melanoma in Situ: A Clinical Conundrum

BACKGROUND: Melanoma is a predominantly cutaneous malignancy associated with sun exposure. Mucosal melanoma is rare and carries a distinct pathogenesis from cutaneous tumors. The vermillion of the lip is a unique site that divides cutaneous from mucosal tissues. Tumors arising on the dry aspect are classified as cutaneous and those of the wet aspect are mucosal. The distinction is importation in tumor staging as all mucosal melanomas are classified as T3-T4b under the current 8th edition American Joint Committee of Cancer (AJCC) guidelines. METHODS: We describe a case of early stage melanoma of the vermillion with associated mucosal melanoma in situ. We discuss nuances of management at this site and the distinctions between cutaneous versus mucosal melanomas with a review of the literature. RESULTS: Our patient was treated surgically with 2-3 cm margins. Residual melanoma in situ was present at the mucosal margin on final pathology which required a second surgery for margin revision. The case was discussed at tumor board with recommendation for no further treatment. CONCLUSIONS: The nuances between the vermillion and mucosal lip must be understood for appropriate staging and treatment of melanomas. The paucity of literature on melanomas affecting this site render management decisions challenging. Multidisciplinary discussion is essential for guiding care.