Clinical and histopathological study of the oral multifocal melanoacanthoma: A case report.

Melanoacanthoma is a blackened mucocutaneous lesion, mainly affecting individuals with dark skin and exhibiting rapid development. Differential diagnosis includes nevus, amalgam tattoo and melanoma. This article reports a case of a 53-year-old white woman, who exhibited multiple blackened lesions on the gingiva and upper lip. After incisional biopsy, the presence of numerous melanin-containing dendritic cells distributed throughout the epithelial thickness, which were S-100 (+), were observed microscopically. Final diagnosis was multifocal oral melanoacanthoma. Follow-up for 28 months has shown appearing of more lesions in gingiva and upper lip. Therefore, the importance of differential diagnosis of oral melanoma with the group of oral pigmented lesions, and possible associated systemic diseases were evaluated. Key words: Melanocytes, pigmentation, oral mucosa, gingiva, differential diagnosis.