Regional lymph node and stromal immunomorphology in colorectal carcinoma and relation to tumour spread.

A quantitative morphometric study of lymphocyte patterns in the stroma and regional lymph nodes was made in 509 cases of colorectal adenocarcinoma and 17 non-invasive adenomas. An increase in the perivascular lymphocytes, and in the size of lymph nodes, germinal centres and paracortical areas was most obvious in 'localized' invasive tumours and significantly more in Dukes' stage B than in stage C. Stage C1, defined as cases where the primary tumours were confined to the wall but with lymph node spread, showed hardly any perivascular lymphocyte aggregates, although in the regional lymph nodes there was relative paracortical, i.e. T-lymphocyte, hyperplasia. It is concluded that the presence of cuffs of perivascular lymphocytes at the tumour edge, and the increased size of tumour-free regional lymph nodes together with the relative and absolute abundance of germinal centres (B-lymphocyte) and paracortical areas (T-lymphocyte), are stage dependent. This is most obvious in stage B. These morphological expressions of host immunoreactivity may well reflect favourable anti-tumour mechanisms.