癌や炎症と鑑別困難な十二指腸・小腸悪性リンパ腫―内視鏡診断を中心に

Malignant Lymphomas in the Duodenum or Small Intestine, Difficult to Distinguish from Inflammatory or Cancerous Lesions

要旨　小腸悪性リンパ腫は，ダブルバルーン内視鏡やカプセル内視鏡の開発で術前の組織診断や病期判定が行えるようになった．小腸病変は多彩であったが，病変の一部に粘膜下の腫瘤を認めること，壁外に腫大したリンパ節や腫瘤を認めることがあること，大きさの割には狭窄や閉塞所見が少ないのが特徴であった．限局型病変では2型進行癌と鑑別が必要になるが，腫瘍の露出が粘膜面にない場合には超音波内視鏡で低エコーの腫瘤像を描出することが重要と思われた．びまん浸潤型を呈するるIPSID，T細胞性リンパ腫，非典型の濾胞リンパ腫やMALTリンパ腫とアミロイドーシスと鑑別が難しい場合にも，他の小腸に粘膜下腫瘍様の病変や顆粒集簇所見など典型所見を見つけることが鑑別診断につながると考えられた．

　Thanks to the advance of capsule endoscopy and double balloon endoscopy, we can make both the histological diagnosis of malignant lymphoma in the small intestine and clinical staging without resorting to surgery. The characteristics of lymphoma resembled various endoscopic findings that might indicate some factors of a submucosal lesion, extra-luminal compression of tumor or enlarged lymph node and late appearance of stenosis or obstruction compared with large tumors. The biopsy specimen led to the histological diagnosis, immunohistochemical findings and subtype of lymphoma. If we encounter a type 2 cancer-like lesion, we should take precise specimens or perform endoscopic ultrasonography because it is useful to detect low-echoic tumors for the diagnosis of malignant lymphoma when the histology is not available. In the diffuse infiltrated type of malignant lymphoma, we have usually to distinguish IPSID（immunoproliferative small intestinal disease）, T cell lymphoma, atypical follicular lymphoma or atypical MALT lymphoma from amyloidosis. In such cases it was important that we obtained precise biopsy specimens and detected submucosal lesions or clusters of multiple whitish granular lesions in the other parts of the small intestine.