4型大腸癌と炎症性腸疾患の鑑別診断

Differential Diagnosis Between Type 4 Colorectal Cancer and Inflammatory Bowel Disease

要旨　4型大腸癌と鑑別を要する炎症性腸疾患として，狭窄を伴う大腸型Crohn病や潰瘍性大腸炎，虚血性大腸炎などが挙げられる．そこで狭窄部の形態学的所見に注目し，注腸造影や大腸内視鏡による鑑別点について検討した．4型大腸癌に特徴的で鑑別に有用な所見として，狭窄部の壁の不整な硬化や多発する粘膜下腫瘍様隆起が挙げられた．一方，炎症性腸疾患では，疾患に特徴的な潰瘍の存在とともに，狭窄部にみられる炎症性ポリープは個々の立ち上がりが明瞭で，発赤を伴うものが多かった．また炎症性腸疾患では，狭窄の周辺腸管にも病変が認められた．これらの形態学的所見に着目すれば，4型大腸癌と炎症性腸疾患の鑑別診断は十分に可能である．

　We mainly examined the morphological characteristics of type 4 advanced colorectal cancer (type 4 cancer), and its differential diagnosis from inflammatory bowel disease. The colorectal stricture complicated with inflammatory bowel disease (Crohn's disease, ulcerative colitis and ischemic colitis etc) sometimes needs to be differentiated from type 4 cancer. With this in mind, paying attention to the morphological findings of the stricture part of each disease, we evaluated the discriminating points between type 4 cancer and inflammatory bowel disease by barium enema and colonoscopic findings. As discriminating points from inflammatory bowel disease, type 4 cancer had remarkable irregularity and rigidity of the stricture wall, and multiple elevated lesions like submucosal tumors. Moreover, identification of characteristic colonic ulcers such as longitudinal or anular ulcers and inflammatory polyps with clear boundaries was useful for the morphological diagnosis of inflammatory bowel disease, differentiating it from type 4 cancer. In addition, abnormal findings were also seen in other parts of the colon in many cases of inflammatory bowel disease.

　If attention is paid to these morphological changes, we think that differential diagnosis between type 4 colorectal cancer and inflammatory bowel disease is possible in many cases.