Disparate cell proliferation and p53 overexpression in colonic crypts with normal epithelial lining found below the neoplastic canopy of conventional adenomas

We previously found colonic crypts with normal epithelial lining but with corrupted shapes (NECS) beneath the adenomatous tissue of conventional adenomas (CoAs). Here we assessed the distribution of proliferating cells (PCs) and explored the possible occurrence of p53‐upregulated cells in the NECS in a cohort of CoAs. Sections from 70 CoAs and from 12 normal colon segments were immunostained with the proliferation marker Ki67. In 60 of the 70 CoAs, additional sections were immunostained for the tumor suppressor p53 protein. NECS with asymmetric, haphazardly distributed single PC or PC clusters were recorded in 80% of the CoAs, with a continuous PC domain in one or both slopes of the crypts in 17%, and with haphazardly distributed single PCs in the remaining 3% of the CoAs. In the 12 normal segments (controls), the colon crypts demonstrated normal shapes with symmetric PC domains limited to the lower third portion of the crypts. In 30% of the 60 CoAs immunostained with p53 the NECS revealed haphazardly distributed p53‐upregulated cells, singly or in clusters. In sum, the apparently normal epithelium of the NECS beneath the adenomatous tissue of CoAs revealed an unprecedented relocation of the normal PC domains. This unexpected event and the occurrence of p53‐upregulated cells strongly suggest that the crypts beneath the neoplastic tissue of CoAs harbor somatic mutations. The accretion of putative mutated NECS beneath the neoplastic canopy of CoA emerges as a previously unaddressed major event, an event that might play an important role in the histogenesis of CoA in the human colon.