Frequent β-catenin nuclear labeling in sessile serrated polyps of the colorectum with neoplastic potential

We obtained 22 sessile serrated adenomas (SSAs) and 19 hyperplastic polyps (HPs) and performed immunolabeling for cytokeratins (CKs) 7 and 20, CDX2, β-catenin, and p53 to determine the role of these markers in aiding distinction of lesions with neoplastic potential. Patients with SSAs more frequently had a prior or coexistent tubular adenoma (P = .004) that was right-sided (P = .00001) and larger (P = .03). No difference in CK7, CK20, or p53 labeling was found after correction for colonic location. However, CDX2 labeling was significantly lower in SSAs (P = .02) and was predominantly confined to the crypt bases, whereas it was diffusely positive in HPs (P < .001). Surprisingly, aberrant nuclear labeling for β-catenin was found in 9 (41%) of the SSAs but in none of the HPs (P < .002). We propose that β-catenin and/or CDX2 immunolabeling may have diagnostic usefulness in the evaluation of serrated polyps. These findings also suggest that Wnt signaling has a role in SSA development.