Neurotropic desmoplastic melanoma

A 62 year old man with a mostly neurotropic, desmoplastic melanoma (DNM) of the lower lip is described. On superficial biopsy this nodular lesion was diagnosed initially as a plexiform neurofibroma with an infiltrative growth pattern. Persistence of growth of the neoplasm led to excisional biopsy 6 mo later, permitting a diagnosis of neurotropic desmoplastic melanoma. There may be distinct differences between those melanomas that are primarily neurotropic and those that are primarily desmoplastic. Immunohistochemical finding support neurotropism or neoplastic replacement of pre-existing nerves rather than neuronal or perineural neoplastic differentiation as the fundamental pathogenesis of this pattern of melanoma in this case.