Abstract
BACKGROUND: The progression from a benign pigmented lesion on the skin to cutaneous melanoma is better understood, and it could be presumed that a similar progression occurs with mucosal lesions. However, to our knowledge, there has never been documentation of melanosis transforming into melanoma over time. OBJECTIVE: To describe a transformation of a mucosal melanosis into melanoma. METHODS: A 53-year-old man with diffuse melanosis of the nasal cavity underwent surgical resection. RESULTS: Pathology revealed melanocytic hyperplasia without evidence of melanoma. The patient was serially examined, with excisions for new areas of melanosis. The pathology progressed to severely atypical melanocytic proliferation and melanoma in situ over a 4-year period. CONCLUSION: Nasal melanosis may be a precancerous lesion and may transform into melanoma. All melanosis should be biopsied with close endoscopic observation. Lesions with dysplasia or atypia should be excised due to potential transformation to melanoma.