亜全摘後に残存腫瘍が自然消失した眼窩内神経鞘腫の1例

Spontaneous regression of orbital schwannoma after subtotal resection

　67歳女性が11年前から右眼視力低下を自覚し，7か月前から右眼眼球突出が生じた。受診時の右視力は0であった。右眼窩内に，嚢胞性で鮮明に造影される腫瘤がCTとMRIで同定され，眼窩内良性腫瘍と診断された。経頭蓋的に摘出を行ったが，周囲の神経と筋肉との癒着が強固で，亜全摘に終わった。病理診断は神経鞘腫であった。右眼窩内に腫瘍の残存が術後のCTで確認されたが，術後1年8か月後のCTとMRI検査で残存腫瘍は消失していた。この間，眼球運動障害は著明に改善した。本例での残存腫瘍の自然消失は，手術により腫瘍への栄養血管が障害され，虚血性壊死による吸収の結果であると考えられた。

A 67-year-old female had noted progressive visual disturbance in her reght eye since 11 years before. Right proptosis had developed 7 months before. The right visual acuity was no light perception when seen by us. Computed tomography (CT) and magnetic resonance imaging (MRI) showed well-defined cystic tumor in the right orbit. Under the diagnosis of benign orbital tumor, she was treated by tumor resection by transcranial approach. Complete removal of the tumor was not possible due to its tight adhesion to the adjacent nerves and muscles. The pathological diagnosis was schwannoma. The presence of residual tumor was confirmed by CT one and four months after surgery. The tumor mass had disappeared when examined by CT and MRI 20 months after surgery. The disturbed eye movement had remarkably improved during this period. The spontaneous regression of residual tumor appeared to be due to ischemic necrosis after injury to the feeder vessels during surgery.