Melanomas of the oral cavity are extremely rare. Their rarity and their independence on exposure to UV radiation make them particularly interesting. The authors analyzed an oral multiphasic melanoma composed by a nodular nonpigmented ulcerated central region, a nodular ulcerated pigmented area, a pigmented nonulcerated region, and an area similar to a dysplastic nevus. They determined the expression of some genes involved in the differentiation and cellular transformation in morphologically different regions of melanoma. All these areas were also analyzed by electron microscopy. The various regions composing the melanoma expressed genes involved in melanogenesis and melanoma progression in a different manner. Electron microscopy observation of ultrathin sections of each region evidenced ultrastructural differences, being the cellular architecture more compromised in the most aggressive parts of the neoplasm. This pilot study identified morphological, molecular, and ultrastructural differences that characterize each region of the multiphasic melanoma.