A Clinicopathological Study of Early (sm) Carcinoma of Colorectum

Forty two cases with carcinoma infiltrating into submucosal layer (sm-carcinoma) of colorectum resected by endoscopic polypectomy and surgical operation were analyzed. Histological findings of the invasion of carcinoma into submucosal vessels (vessel invasion) and the infiltration to excised margin of polypectomized specimen (cut end infiltration) were compared with lymphnode metastasis and remnant carcinoma tissue of resected bowel wall. Gross configuration of sm-carcinoma was classified into three types. The first type is the shape with constricted base or pedunculated (Isp・Ip), the second sessile or hemisphered (Is・IIa), and the third flat elevated with depressed top (IIa+IIc). Metastatic lymphnodes were found in 10 cases (24%). High incidence (38%) of metastasis to lymphnode was detected in the cases with IIa+IIc shaped carcinomas. Endoscopic polypectomy were performed to 20 cases with polypoid shaped carcinomas, and metastatic lymph nodes were found in 3 cases (15%). The findings of vessel invasion were highly correlative with lymph node metastasis, and detected easily from the observation of ordinary pathological specimen in the cases with large Is・Ip-shaped or IIa+IIc-shaped carcinomas resected by surgical operation. In contrast, the detection of vessel invasion was so difficult in cases of Is・IIa-shaped carcinomas excised by endoscopic polypectomy that diagnosis was difficult by routine pathological examinations, and the careful obsevation of large number of additional serial histological sections was required. The findings of cut end infiltration were found in eight polypectomized specimens, and remnant carcinoma tissues were detected on resected bowel wall at polypectomized part in one case out of 3 cases with Is・IIa-shaped carcinomas and four cases out of 5 cases with Isp・Ip-shaped carcinomas, respectively