大腸悪性リンパ腫の画像診断

Pictorial Diagnosis of Malignant Lymphoma of the Large Intestine

要旨　大腸原発悪性リンパ腫10例13病変について大腸X線および内視鏡所見を中心に検討した．肉眼形態は限局型とびまん型に分けられ，限局型は隆起型7病変，潰瘍型5病変，びまん型は1病変であった．隆起型は表面平滑な例では粘膜下腫瘍と診断されたが，粗大結節状を呈し，癌と鑑別困難な例もあった．潰瘍型は周堤が平滑で潰瘍の辺縁が鮮明なものは粘膜下腫瘍と診断されたが，2型癌と鑑別困難な例もあった．びまん型では炎症性腸疾患との鑑別も問題となった．画像診断のみで悪性リンパ腫と診断できるような特徴的な所見はなく，生検で診断できた例も42.9％にすぎなかった．本症は多彩な肉眼形態を取るので，他の腫瘍性疾患はもちろん炎症性疾患と鑑別困難な画像所見を呈しうることを知っておくことが重要であり，悪性リンパ腫に類似する画像を呈した他疾患症例も併せ呈示した．

　Thirteen lesions from 10 cases of primary malignant lymphoma in the large intestine were analyzed from the radiologic and endoscopic viewpoints. Macroscopic shapes of our cases were classified as follows: localized type, seven lesions; ulcerative type, five lesions; and diffuse type, one lesion. Protruding type lesions with smooth surface were initially diagnosed as submucosal tumors, but it was difficult to distinguish a protruding type lesion with rough surface from cancer. Ulcerative type lesions with smooth surrounding are and shape edge were diagnosed as submucosal tumors, but some of them mimicked type 2 cancers. Differential diagnosis of the diffuse type included inflammatory bowel diseases. There was no pathognomonic findings which indicated malignant lymphoma, and only 42.9% of the biopsy specimens disclosed definitive diagnoses. It would be important to know that this disease may show various macroscopic shapes which need to be differentiated from inflammatory bowel diseases as well as other tumorous diseases. We demonstrated some cases whose macroscopic pictures mimicked malignant lymphoma.