[Oral amelanotic melanoma--report of a case with desmoplastic changes at the site of lymph node metastasis].

Amelanotic melanoma of the gingiva in a 59-year-old Japanese woman is presented. The histologic diagnosis of melanoma was confirmed by the concurrent lentigo maligna in the palatal mucosa and desmoplastic malignant melanoma (DMM) in the metastatic foci of a cervical lymph node. Electron-microscopical observations revealed that DMM cells exhibited mesenchymal metaplasia or myofibroblastic differentiation. Accordingly, collagen synthesis of the tumor cells was suspected. A review of 31 reported DMM cases is also presented.