Multinucleate epithelial change in colorectal hyperplastic polyps – a review of 27 cases

Abstract

Aim: To document the histological features of multinucleated epithelial giant cells (MEG) in colorectal hyperplastic polyps and determine a possible aetiological agent. Methods: Hyperplastic polyps were assessed for MEG during the routine reporting at a private laboratory and public hospital laboratory. The histological features and clinical data were assessed and immunohistochemical stains performed to assess for viral infection (CMV, HSV 1&2) and to assist in the assessment of dysplasia (Ki-67, â-catenin and p53). Ultrastructural examination was performed in one case. Results: MEG were identified in 27 polyps (24 patients). There was active inflammation in the polyps in nearly all cases (n=24) and most showed changes in adjacent normal non-hyperplastic bowel mucosa such as focal basal cryptitis and apoptosis of crypt epithelium (16 patients). Immunohistochemistry for CMV, HSV and p53 was negative in all cases. The MEG showed nuclear positivity for the proliferative marker Ki-67 and membranous positivity for beta-catenin. Ultrastructural studies failed to reveal viral particles. Conclusions: All the polyps containing MEG showed active inflammation and apoptosis, and in most there was also focal inflammation and apoptosis in the adjacent mucosa. Sodium phosphate bowel preparation is known to induce a spectrum of changes in previously normal colonic mucosa including aphthoid lesions, denudation of the superficial epithelium, focal active inflammation, increased crypt cell apoptosis, increased crypt cell epithelial proliferation and ulceration. The pro-inflammatory action of NaP bowel preparation in conjunction with the increased epithelial proliferation characteristics of hyperplastic polyps could be the mechanism for the MEG formation.