[Primary malignant melanoma of the nasal mucosa with orbital involvement. Case report].

Melanoma of nasal mucosa is a rare tumor, and only 0.5% of the malignant melanomas arises in the nasal cavities. This article reports a case of an achromatous melanoma localized in the nasal fossae, with orbital involvement and paresis of the extraocular muscles, which was studied by means of contrast-medium CT scan and histological and immunohistochemical evaluation. Of particular interest is the voluminous extension of the tumor mass upon initial diagnosis.