[A case of malignant melanoma with orbital metastasis which caused the first symptoms].

A thirty-four-year-old man was admitted to our hospital because of the disturbed visual acuity and pain on the eye movement of the right eye. He had prominent right eye and CT-scan and MRI of the brain disclosed a tumor which could be obviously distinguished from the extraocular muscles, optic nerve and the bulb of eye in the retrobulbar region. On operation we identified dark-red solid tumor which was 3.0cm in diameter, and diagnosed it malignant melanoma pathologically. Because postoperative study detected amelanotic melanoma in the white patch on the right upper extremity, this right orbital tumor was considered to be the metastasis of it from the right upper extremity. Metastatic malignant melanoma of the skin to the orbit is very rare, while most of the eye-associated malignant melanoma originates from uveal tract, special choroid, and conjunctiva. This case was the 26th case of these in the world and the first case in Japan, furthermore the 4th case in the world whose first symptoms were caused by the orbital metastasis.