| [ Summary ] |
In Japan, there are presently two classifications of colorectal carcinoma, 1) classification by relative value, 2) classification by absolute value of the amount of submucosal invasion. Four histological factors correlate with a significantly higher incidence of lymph node metastasis. They are, 1) two types of carcinoma, sm2 (up to two thirds of the submucosa) and sm3(with deeper invasion), 2) moderate or poorly differentiated carcinoma in the submucosal invasive front, 3) that with vessel permeation, 4) carcinoma with chromogranin immunoreactivity. Colorectal carcinoma with low grade atypia, regardless of grade of submucosal invasion, showed no lymphnodal metastasis. DNA aneuploidy patterns showed higher incidence of lymphnodal metastasis, compared with those with diploidy patterns. Desmoplastic stromal reactions, were not observed on the surface of sm1 (up to 500 pm from the muscularis mucosa), but were seen in the greater part of sm2 and sm3 specimens. These results indicate that surgical excision should be made when a desmoplastic stromal reaction is detected by biopsy. Endoscopic mucosal resection is recommended when there is no reaction. If the carcinoma is of the sm2 level or greater, additional excision is required. If an sm2 or sm3 carcinoma is of the aneuploid type, or if there is chromogranin immunoreactivity or a moderately or poorly differentiated adenocarcinoma at the invasive front, lymphnodal metastasis is quite likely. Thus, even if colostomy is unavoidable, surgery should be performed in such cases. |