[Melanoma developped on nevus of Ota without ocular melanosis. Apropos of an anatomo-clinical case].

The naevus of Ota is a congenital pigmentary disorder usually involving the skin of the face in areas supplied by the first and second branches of the trigeminal nerve. Ipsilateral ocular melanosis is associated in 2/3 of the cases. The naevus occurrs most often in Asians. There have been 66 reported cases of malignant transformation of the naevus of Ota, generally affecting caucasians: 23 were melanomas of the eyeball (mostly of the choroid), and 13 were orbital melanomas. Only 4 cases of melanomas associated with a naevus of Ota without ocular melanosis have been previously described. We report a new case of orbital melanoma affecting a 30-year-old man. This melanoma complicated a right type III of Tanino naevus of Ota without ocular melanosis. The location of the tumor to the orbital apex and its extension to the spheno-cavernous area was responsible for an ipsilateral loss of vision without proptosis, which has not yet been described in any case of naevus of Ota without ocular melanosis.