粘膜下腫瘍様の形態を呈した大腸癌の臨床および画像的特徴

Endoscopic Diagnosis of Colorectal Cancer Resembling Submucosal Tumor

要旨　肉眼的に粘膜下腫瘍様の形態を呈した大腸癌5病変の臨床および内視鏡的特徴について検討を行った．5病変中3病変がsm癌(sm2-3癌)でその頻度は当科における大腸sm癌の1.4％(3/222)であった．残りの2病変は進行癌であった．病変部位はS状結腸，上行結腸にみられ，大きさは20mm以下，sm癌は全病変10mm以下と小サイズであった．肉眼形態はsm癌で表面隆起型と隆起型，進行癌は5型病変であった．内視鏡所見はいずれの病変も緊満感を伴い，浅い陥凹を有する病変でbridging foldを有する病変はsm癌では1例も認めず，進行癌で，1例認めるのみであった．このような病変の診断においては陥凹部のpit patternを観察することが重要と考えられた．

　In order to clarify clinical and endoscopic features of colorectal cancer resembling submucosal tumor, five invasive colorectal cancer lesions were studied. Three of the five were submucosal massive invasive cancers and two were advanced cancers. Lesions were seen in the sigmoid colon or ascending colon. Mean size of the lesions was 10.8mm (4-19). Gross appearance was 0-IIa or 0-I type in submucosal massive invasive cancer and type 5 in advanced cancer. As for endoscopic features, we could see shallow depression in all lesions by endoscopy. Bridging fold was seen in only 1 lesion (advanced cancer). As for pit pattern by stereomicroscopy, we could see type VI pit pattern in all the lesions.

　In conclusion, when we see lesions resembling submucosal tumors in endoscopy, we must be careful about the presence of depression and type V pit pattern at the depression.