The expression of p53, Ki-67 and urokinase plasminogen activator receptor in colorectal adenomas with true invasion and pseudoinvasion.

The recognition of pseudoinvasion is important in the differential diagnosis of adenocarcinoma in patients with adenomas. This distinction might occasionally be difficult, particularly when the dysplasia is pronounced. The present study was undertaken in order to investigate whether the immunohistochemical expression of p53, Ki-67 and the urokinase plasminogen activator receptor (uPAR) was different in adenomas with true invasion and pseudoinvasion. We studied 26 formalin-fixed, paraffin-embedded tumor samples, consisting of 10 cases of adenomas with pseudoinvasion and 16 cases of adenocarcinomas in adenomas. In this series of selected histologically typical cases a constant moderate or strong reaction for uPAR was present at the invasive front in all of the 16 adenomas with adenocarcinoma, but only focally in one of 10 adenomas with pseudoinvasion. The reactions for p53 and Ki-67 showed only minor differences. In conclusion, the immunohistochemical reaction for uPAR seems to be a useful supplement in cases without typical histology or with severe dysplasia.