De novo desmoplastic neurotropic melanoma of the lower lip: a neoplasm with ominous behavior.

Desmoplastic neurotropic melanoma represents a rare histologic variant of malignant melanoma that is characterized by a proliferation of spindle cells in a densely collagenous stroma with pronounced neurotropism. A 60-year-old man appeared for evaluation of a mass in the lower lip. The labial mucosa was intact, and the lesion had been present for 2 months. The tumor was surgically removed, and after immunohistochemical and ultrastructural analysis it was diagnosed as desmoplastic neurotropic melanoma. The tumor recurred 6 months later, with involvement of the inferior alveolar nerve.