Agreement in interpreting villous elements and dysplasia in adenomas less than one centimetre in size

Abstract

Background: Villous elements and dysplasia grade in small adenomas are used in many countries to guide post-polypectomy colonoscopy intervals.

Aims: Measure agreement in interpretation of villous elements and dysplasia in small adenomas.

Methods: Consecutive endoscopically resected adenomas <10mm in size (203 adenomas less than 6mm and 149 adenomas 6-9 mm in size) were reviewed by 3 expert gastrointestinal pathologists. Interpretations were compared to routine clinical pathology readings at our institution and to each other.

Results: All pathologists used the same definitions for villous and tubular histology. The overall kappas for villous elements in <6mm and 6-9 mm adenomas were 0.29 and 0.26, respectively. Interpretation of dysplasia grade had kappas of 0.02 and 0.09 for adenomas <6mm and 6-9 mm, respectively. Two expert pathologists who used cytologic criteria had much higher fractions of high grade dysplasia compared to the third expert and the pathologists at our centre, who relied on architectural criteria.

Conclusions: Villous elements and dysplasia grade in small adenomas are problematic as determinants of post-polypectomy surveillance intervals. Uniform pathologic criteria for dysplasia grade are needed.

Keywords: Adenomas; Colonoscopy; Dysplasia; Reproducibility; Surveillance; Villous elements.