Issues

The image shows immunohistochemical staining of a human colonic polyp biopsy, demonstrating intestinal epithelial cells highlighted by nuclear staining (brown) surrounded by smooth-muscle cells (red) and fibroblasts (purple). The distinction among different types of colonic polyps often presents a significant diagnostic challenge with high interobserver variability. We identified an extracellular matrix protein, agrin, as a novel biomarker identifying high-risk colonic polyps by its localization in the muscularis mucosa underlying the colonic epithelium. For details, see article by Rickelt and colleagues on page 1277 of this issue.