Morphologic progression of polypoid colon cancer invading muscularis propria.

To clarify the morphologic progression of polypoid growth in colon cancer invading the musculasris propria, we assessed the morphologic changes in 50 such cancers according to the size and shape of the polyp. The shape of the head of the polyp was defined at the widest slice as semicircular or ulcerated. As the cancer invaded the musculasris propria, the head of the polyp thickened and the structure of the head progressively collapsed, causing its shape to change from semicircular to ulcerated. The proliferating cell nuclear antigen percentage of cells with positively stained nuclei labeling index, determined at the deepest point of invasion, significantly correlated with the morphologic progression of the polyp from semicircular to ulcerated (63.2 +/- 6.7% and 74.9 +/- 7.2%, respectively; P < 0.05). These results indicate that the proliferating cell nuclear antigen labeling index may be a useful marker for the morphologic progression of invasive colonic polyps.