Effect on lymph node status of triple levelling and immunohistochemistry with CAM 5.2 on node negative colorectal carcinomas

Several papers have recently assessed whether immunohistochemistry increases the accuracy of staging in node negative colorectal carcinomas, by showing micrometastases. The results have been contradictory. In this paper 542 nodes which were negative for tumour on routine sectioning, were stained with CAM 5.2. In addition, the tissue was levelled three times, this technique being more economical, to see if either or both techniques increased the pick up of micrometastases. Six nodes showed positive staining of occasional cells in the subcapsular and paracortical sinuses, but these were cytologically benign on review and were not thought to represent metastatic tumour. Triple levelling did not show any additional micrometastases.