眼窩内腫瘍で発見された皮膚悪性黒色腫の1例

A Case of Malignant Melanoma with Orbital Metastasis which Caused the First Symptoms

　症例は34歳男性。右眼球視力障害と眼球運動痛を主訴に1988年1月当科を受診した。右眼球突出を認め，頭部CT，MRI像にてretrobulbar regionに外眼筋，神視経，眼球とは明らかに区別される腫瘤を認めた。手術により直径約3cmの暗赤色，弾性硬の腫瘤を認め，病理学的所見から悪性黒色腫と診断した。術後の検索により，右上肢の自斑からamelanotic melanomaが検出され，右眼窩の腫瘤はこの眼窩内への転移と考えられた。眼科領域の悪性黒色腫はブドウ膜，特に脈絡膜，もしくは結膜から発生するものが大部分であり，皮膚悪性黒色腫の眼窩内への転移は極めて珍しく，本例は世界でも25例目，本邦第1例である。更に眼窩内転移による症状を初発症状とした例は，本例が第4例目であった。

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 pos-toperative study detected amelanotic melanoma in the white patch on the right upper extremety, this right orbital tumor was considered to be the metas-tasis of it from the right upper extremety. Metas-tatic malignant melanoma of the skin to the orbit is very rare, while most of the eye-associated malig-nant melanoma originates from uveal tract, especial choroid, and conjuctiva. 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.