びまん浸潤型大腸癌の病理

Diffusely Infiltrating Carcinoma of the Colon and Rectum

要旨　8例のびまん浸潤型大腸癌について検討した．大きく2種に分類され，1つは印環細胞癌あるいは低分化腺癌で，硬癌あるいはlinitis plastica型の癌，他の1つは癌性リンパ管症とも称される広汎・高度なリンパ管浸潤によりびまん性浸潤を示すものである．前者は6例，後者は2例．印環細胞癌あるいは低分化腺癌は，粘膜面に浅い潰瘍を形成するが，その深さはせいぜい粘膜下層の上層までである．AB・PAS染色では，AB（＋）PAS（－）粘液が大部分で，胃癌の印環細胞癌の粘液の染色態度と異なっていた．径8mmの印環細胞癌も併せて検討し呈示した．

　Eight surgically treated cases of diffusely infiltrating carcinoma of the colon and rectum were examined as well as a case of small carcinoma ; 4 cases of signetring cell carcinoma, 2 cases of poorly differentiated adenocarcinoma, and 2 cases of moderately differentiated adenocarcinoma with extensive carcinomatous lymphangiosis. Macroscopically, signet-ring cell carcinoma and poorly differentiated adenocarcinoma were similar to those of scirrhous or linitis plastica type gastric carcinoma ; marked thickening of the colonic wall, prominent especially in the submucosal layer due to desmoplastic carcinomatous infiltration. The mucosal surface looked granular or coarse granular or had irregular gyriform folds as the result of contraction of the submucosa. The mucus in the signet-ring cell carcinoma was mainly alcianophilic, demonstrated by double staining of alcian blue and PAS.

　In two cases of moderately differentiated adenocarcinoma with diffuse infiltration, lymphangitic permeation was conspicuous in the submucosal layer as well as in the muscular and subserosal layers. The secondary intramucosal invasion via lymphatic vessels was the cause of coarse granular appearances.

　The smallest signet-ring cell carcinoma in our case series was only 8 mm in diameter and had already showed scirrhous infiltration in the submucosal layer and lymphangitic permeation.

　The prognosis of diffusely infiltrating carcinoma of the colon is so poor that early dianosis is mandatory to improve the clinical course.