眼窩腫瘍手術後長期を経て発生した多形腺腫の1例

Recurrence of pleomorphic adenoma after a long interval in an operated case of orbital tumor

　73歳男性が右眼窩内軟骨肉腫に対して眼球摘出，腫瘍摘出と放射線照射を35年前に受けた。以後装用中の義眼が落ちやすくなり，腫瘍雨発の疑いで紹介され受診した。細胞診でクラスVの軟骨器質が眼窩内にあった。コンピュータ断層撮影（CT）で，右眼窩内に腫瘍の浸澗による骨破壊像と，多数の点状の高信号部を含む中等度のコントラストの部位があった。磁気共鳴画像（MRI）で，同部位はT1強調画像で低信号，T2強調画像で低信号と高信号が混在し，Gd-DPTAを使った造影MRIでほぼ全体が増強していた。これらの所見は軟骨肉腫の再発を否定するものではなかった。腫瘍切除術を行い，病理学的に良性の多形腺腫と診断された。以後28か月再発はない。

A 73-year-old male had received, 35 years ago, enucleation, tumor resection and radiation for chondrosar-coma in his right orbit. He was referred to us for unstable prosthesis. Biopsy of the orbital content showed class V car-tilate matrix. Computerized tomography (CT) showed a moderate-constrast lesion including multiple high-contrast spots in the right orbit. Findings were present suggestive of bone erosion due to invasion of the tumor. Magnetic reso-nance imaging (MRI) showed low intensity on T1-weighted images and mixture of high and low intensity on T2-weighted images. The whole orbital content showed enhancement by MRI with Gd-DTPA. The findings did not rule out recurrence of chondrosarcoma. Resection of the tumor led to the histopathological diagnosis of benign pleomorphic adenoma. There has been no recurrence during 28 months of follow up.