Negative colorectal polyp biopsies: the utility of cutting deeper levels.

The objectives of this study were to determine the frequency with which deeper levels reveal a lesion in polyp biopsies where no polyp was found on initial sections and to identify features that predict such occult (histologically unapparent) lesions. All initially negative biopsy specimens were accumulated over an 18-month period. Following standard sections, three to ten levels were cut, 50 μm apart. The presence of any lesion, the level at which it was found, the location, number and size of fragments, number of levels obtained, presence of any lymphoid aggregate, endoscopic size and appearance, and bowel preparation quality were recorded. There were 214 specimens, mean patient age 61.4 years (range 27-86 years). Deeper levels revealed a lesion in 52/214 (24.3 %) cases; 76.9 % were tubular adenomas (TA), 21.2 % were hyperplastic polyps, and one was a leiomyoma. All TAs were negative for high-grade dysplasia and malignancy. The mean level at which TAs were found was 1.85 (range 1-9). Male sex (p = 0.021) and right-sided location (p = 0.0075) were statistically significant predictors of an occult TA. As the presence of an adenoma affects screening, pathologists should consider "pursuing" polyps when initial sections reveal no lesion, after ascertaining the incidence of occult lesions in their own practice.