Pit pattern analysis using acetic-acid magnification chromoendoscopy in predicting histopathology of small colorectal polyps. The diagnostic yield and intra-/inter-observer reproducibility

Aim: The purpose of the study was to assess the diagnostic yield of acetic-acid magnification chromoendoscopy and Kudo’s classification of pit patterns in predicting neoplastic histopathology of small colorectal polyps, and to assess intra- and inter-observer reproducibility in classifying small colorectal polyps to particular pit patterns.

Material and methods: The prospective study was performed on 40 consecutive patients referred for non-therapeutic colo-noscopy in whom 50 polyps with a diameter of less than 10 mm were found (endoscope Olympus CF Q160Z). An acetic acid solution (1.5%) and Kudo’s pit pattern classification were used. All polyps were removed and examined histopathologically.
The pit pattern was judged by an endoscopist immediately after colonoscopy. Then, anonymized digital video recordings of magnification colonoscopies were secondarily evaluated after
4 weeks (intra-observer reproducibility) by 2 other endoscopists. Inter-observer reproducibility was assessed using video recordings by 3 endoscopists comparing judgements of pit patterns (3 pairs of comparisons).

Results: Fifty polyps were evaluated: 25 hyperplastic, 18 ade-nomas, 6 with normal mucosa and 1 adenocarcinoma. During magnification colonoscopy 30 polyps were judged as non-neoplastic (pit pattern I and II in 5 and 25 cases, respectively) and 20 polyps were classified as a neoplastic pit pattern (III L and IV in 18 and 2 cases, respectively). Sensitivity and specificity of the pit pattern analysis in predicting neoplastic histopathology were 63.2 and 74.2%, respectively. Intra-observer reproducibility in classifying polyps to non-neoplastic and neoplastic pit patterns was very good (k value 0.88).
K values for assessment of inter-observer (three pairs of observers) reproducibility were 0.71, 0.38 and 0.32.

Conclusions: Acetic-acid magnification endoscopy is of a li-mited value in predicting neoplastic histopathology of small colorectal polyps with acceptable intra-observer reproducibility and unsatisfactory inter-observer reproducibility.