Animal-type malignant melanoma associated with nevus of Ota in the orbit of a Japanese woman: a case report.

We present a patient with an animal-type malignant melanoma associated with the nevus of Ota in the orbit who showed a good prognosis after a combination of orbital extirpation, chemotherapy, stereotactic radiotherapy, and gamma knife. A 42-year-old Japanese woman presented with two tumors, one pathologically diagnosed as right-sided intraconal animal-type malignant melanoma and the other intracranially, presumed to be of the same pathogenesis and both were considered to have arisen from the nevus of Ota. She underwent an extirpation of the orbit, chemotherapy (DAV therapy, which is a combination of dacarbazine, nimustine, and vincristine), stereotactic radiotherapy (54 Gy in 27 fractions), and gamma knife (marginal dose was 17 Gy, target volume was 0.2 ml). She has been alive for 33 months since the extirpation, with no sign of local recurrence, new metastasis, nor enlargement of the intracranial tumor. Not just combination therapy but also the low malignancy of animal-type melanoma may have contributed toward the good prognosis.