Malignant melanoma of choroid in a case of nevus of Ota.

A white woman with unilateral nevus of Ota presented with visual loss and an intraocular mass resembling a choroidal melanoma. Indirect ophthalmoscopy, fluorescein angiography, ultrasonography, and radioactive phosphorus uptake corroborated the clinical impression and surgery was advised. Following enucleation, the specimen was examined with light microscopy, which revealed a mixed cell type malignant melanoma of the choroid. Electron microscopy disclosed the presence of premelanosomes in the episclera, indicating that the episcleral pigmentation is a result of melanocytic evolution. This paper represents the tenth report in the literature of choroidal melanoma occurring in a patient with nevus of Ota, and the first electron-microscopic study of an eye with this association of lesions.