Poorly differentiated adenocarcinoma of the colon and rectum: clinical characteristics.

Background/aims: The aims of this study were to assess the prognosis and histopathological factors of poorly differentiated colorectal adenocarcinoma, and the clinical relevance of the proposed histopathological sub classifications.

Methodology: Fifty eight patients with poorly differentiated adenocarcinoma were enrolled in this study. According to the lymphatic canal spread in tumor tissue, they were classified into lymphangitic type (tumor spread beyond the intra mucosal tumor space through the lymphatic canal widely) and non-lymphangitic type (tumor spread within that space). Next, they were sub classified into medullary, intermediate and scirrhous types according to the amount of fibrous stroma. In addition, immunohistological examinations were performed on the expression of an intercellular adhesion molecule (E-cadherin).

Results: In 33 cases (57%) Lymphangitic type was present and in 25 cases non-lymphangitic type (43%) was present. In the lymphangitic types, 5 cases were medullary type (15%), 17 cases were intermediate type (52%) and 11 cases were scirrhous type (33%) that included 2 cases of signet ring cell carcinoma. In the non-lymphangitic types, medullary type was dominant (20 cases, 80%) while intermediate type and scirrhous type were 3 cases (12%) and 2 cases (8%), respectively. The survival rates were calculated for both types and a large difference was found in terms of 5-year survival rate; 0% for lymphangitic type and 72% for non-lymphangitic type (p<0.05). There was no correlation found between the expression of cadherin and the subclassification.

Conclusions: In conclusion, a wide tumor infiltration and growth in lymphatic vessels appears to be an important prognostic factor for poorly differentiated adenocarcinoma compared to the metastasis patterns.