Regional lymph node metastases in carcinoma of the left side of the colon and rectum: CT demonstration.

The distribution of regional lymph node metastases in carcinoma of the left side of the colon, rectum, and anus can be well shown by routine CT of the abdomen and pelvis. Recognition of the location of nodes in the mesocolic, left colic, and IMA nodal groups can help in developing a systematic approach to the detection of nodal metastasis. This can be especially important in preoperative planning for cases in which resection may be curative. In addition, an understanding of the distribution of nodal metastasis will make it possible to recognize early recurrent nodal disease, particularly with an increase in associated increase in levels of carcinoembryonic antigen, and to predict certain clinical sequences such as hydronephrosis of the left kidney associated with left colic nodal metastases.