眼窩顆粒細胞腫の1例

A case of granular cell tumor of the orbit

　52歳男性が2か月前に右眼窩下縁に小指頭大の固い腫瘤を触知し，上下複視が生じたので受診した。右眼圧が24mmHgである以外には異常所見はなかった。CTとMRIで右眼球の下方に腫瘤があり，石灰化や骨破壊像はなかった。腫瘤はT1強調画像でintermediate intensity,T2強調画像で脂肪よりも低いlow intensltyであり，Gdで弱く造影された。手術で20×12×10mm大の固い腫瘤を亜全摘した。病理組織学的に腫瘍細胞は好酸性の顆粒が特徴的で，免疫組織学的にS−100蛋白陽性であり，眼科領域では稀な顆粒細胞腫と確定診断された。

A 52-year-old male presented with vertical diplopia. He had noticed a hard mass in the lower margin of the orbit 2 months before. He showed no abnormal findings except the orbital tumor and intraocular pressure of 24mmHg in his right eye. Computerized tomography (CT) and magenetic resonance imaging (MRI) showed a tumor inferior to the right eyeball. Calcification or bone destruction was absent. MRI imaging of the tumor showed intermediate intensity on T1-weighted image and low intensity on T2-weighted image.The tumor showed slight enhancement with gadolinium-DTPA. Surgery showed a hard tumor mass measur-ing 20mm×12mm×12mm in size. By histopathology, the tumor cells had abundant cytoplasm and eosino-philic granules. The tumor was diagnosed with granular cell tumor, which is a rare occurrence in the orbit, af-ter immuohistologic studies showed positive for S-100 protein.