小さな小腸病変より成る全身性疾患―アミロイドーシス

Amyloidosis

要旨　消化管はアミロイド沈着の好発臓器であり，なかでも十二指腸，小腸は最も沈着の高度な部位である．アミロイドーシスの沈着様式はアミロイド蛋白別に特異性がみられ，蛋白ごとに形態学的特徴が異なる．AAアミロイドーシスでは粘膜固有層と粘膜下層血管壁が沈着の主体となり，内視鏡的には微細顆粒状隆起が多発する粗糙な粘膜が特徴的である．ALアミロイドーシスでは粘膜筋板と粘膜下層，固有筋層へ塊状沈着傾向がみられ，内視鏡的には粘膜下腫瘍様隆起の多発と皺襞の肥厚が特徴的である．今後はカプセル内視鏡やダブルバルーン内視鏡による知見も増えてくることが期待されるが，本症の形態学的特徴を念頭に置いて診断することが重要と思われた．

　Clinicopathologic findings of gastrointestinal tract lesions were investigated in patients with amyloidosis according to the chemical type of amyloid proteins. Endoscopic examination of the gastrointestinal tract revealed considerable differences between amyloid proteins. In cases of AA amyloidosis, there was a coarse mucosal pattern with innumerable fine granular elevations, which correlated with expansion of the lamina propria by amyloid deposits. In cases of AL amyloidosis, there were polypoid protrusions and invariable thickening of the folds, which reflected massive amyloid deposits in the muscularis mucosa, submucosa and muscularis propria. Progression and wider use of capsule endoscopy and double balloon endoscopy will enable detailed diagnosis for amyloidosis from now on. It is important to understand characteristic endoscopic features of amyloidosis for the diagnosis.