Contralateral orbital melanoma 28 years following enucleation for choroidal melanoma

A 79-year-old man underwent right enucleation for a choroidal melanoma. Twenty eight years later he presented with a nine month history of progressive left proptosis. Orbital imaging revealed a large left lateral orbital mass, extending back to the orbital apex, which was found on subtotal resection to represent an orbital melanoma. Skin survey was negative, and the prior right choroidal melanoma was the most likely metastatic source. He underwent radiotherapy of the residual tumor at the left orbital apex, as well as radiotherapy of small liver and lung nodules felt to likely represent metastatic melanoma. Five years later, he was still alive and well, with no further tumor demonstrable in the orbit, lung or liver. This case demonstrates the indolence and favorable prognosis of some orbital melanomas. We discuss some hypotheses that may explain such tumor behavior. While melanoma is often considered a highly malignant and lethal tumor, some melanomas are characterized by a more benign course. In addition, certain melanomas may respond to radiotherapy.