固有筋層への浸潤を認めたS状結腸結節集簇様病変の1例

Nodule-Aggregating Tumor of the Sigmoid Colon Invading the Muscularis Propria Layer, Report of a Case

要旨　患者は62歳，女性．排便時出血を主訴に当センターを初診した．大腸内視鏡検査を施行したところ，S状結腸に大きさ約25mmの結節集簇様病変を認めた．病変は丈が低く均一な結節からなる部分と，それと連続して丈が高く発赤調で著明な緊満感を有する部分より構成されていた。緊満感を有する部分では分葉傾向が消失し，頂部に白苔を伴った浅い小陥凹を認めた．内視鏡所見からは表面構造を比較的保ちながら粘膜下層へ深部浸潤した大腸癌と診断した。注腸X線検査では，病変はS状結腸の大きさ25mmの立ち上がりが明瞭な隆起性病変として描出され，表面には大小不均一な結節を認め，大きな結節の頂部に不整形の浅い陥凹を示すバリウム斑がみられた．側面像では弧状変形を呈していた．超音波細径プローブ所見を加味し，病変は丈の高い緊満感を有する部分において粘膜下層に深部浸潤した癌と最終診断し，S状結腸切除術を施行した．病理組織学的には丈の高い緊満感を有する部分で深達度mpへ浸潤した高分化腺癌であった．また丈の低い均一な結節部分では癌は粘膜内にとどまっており，adenomaの成分はみられなかった．本例は比較的表面構造を保ちながら深達度mpまで深部浸潤した癌であり，大腸癌の発育進展を考えるうえで興味ある症例と思われ報告した．

　A 62-year-old woman visited our center, complaining of hematochezia. Colonoscopic examination revealed a nodule-aggregating tumor, approximately 25 mm in size, in the Sigmoid colon. It consisted of a slightly protruding part with homogenous nodules and a reddish protruding part with macroscopic fullness. In the latter portion, the tendency of segmentation was lost and a small shallow depression was observed at the top. From these colonoscopic findings, the tumor was diagnosed as colon cancer (nodule-aggregating-type) with massive submucosal invasion. Barium enema radiograph revealed an elevated lesion with heterogenous nodules, 25 mm in size in the Sigmoid colon. A thin, irregular barium collection was seen in the top of the large nodules. The profile view showed a semilunar deformity. From these findings, combined with highfrequency ultrasound probe findings, it was finally diagnosed as a nodule-aggregating-type cancer with massive submucosal invasion. Sigmoidectomy was perfomed. In the resected specimen, there was a noduleaggregating-type tumor with a small depression, measuring 25 × 22 mm in size.

　Histologically, it was a well differentiated adenocarcinoma with invasion of the muscularis propria.

　The case was thought to be noteworthy for understanding the growth and progression of colon cancer.