Challenging diagnostic issues in adenomatous polyps with epithelial misplacement in bowel cancer screening: 5 years’ experience of the Bowel Cancer Screening Programme Expert Board

Abstract

The diagnostic difficulties of differentiating epithelial misplacement from invasive cancer in colorectal adenomatous polyps have been recognised for many years. Nevertheless, the introduction of population screening in the UK has provided extraordinary diagnostic problems. Larger sigmoid colonic adenomatous polyps, those most likely to show epithelial misplacement, are specifically selected into such screening programmes because these polyps are likely to bleed and screening is based on the detection of occult blood. The diagnostic challenges associated with this particular E B : this is a review of the first five years of its practice, during which time 256 polyps from 249 patients have been assessed. Indeed, the constitution of the Board has been with three pathologists because those pathologists do not necessary agree and a consensus diagnosis is required to drive appropriate patient management. However, this study has shown substantial levels of agreement between the three Expert Board pathologists whereby the ultimate diagnosis has been changed, from that of the original referral diagnosis, by the Board in half of all the polyps, in the substantial majority from malignant to benign.In 3% of polyp cases, the Expert Board consensus has been the dual diagnosis of both epithelial misplacement and adenocarcinoma, further illustrating the diagnostic difficulties. The Expert Board of the Bowel Cancer Screening Programme in the UK represents a unique and successful development for an extraordinary diagnostic conundrum created by the particular characteristics of bowel cancer screening.

Histologic Factors Associated With Need for Surgery in Patients With Pedunculated T1 Colorectal Carcinomas

“…45 It is very difficult to account for this because diagnosis of T1 CRC in pedunculated lesions is a contemporary challenge, even for expert pathologists, and a golden standard does not exist. 45,46 The incidence of 5.2% used for our analysis seems justified because there were also cases revised as T2 CRC, and this is in good agreement with previous reported incidence rates varying between 3% and 7%. [4][5][6][7] Ikematsu et al 2 showed recurrence rate to be significantly higher in patients with high-risk T1 rectal cancer treated with endoscopic resection without adjuvant surgery (16.2%) compared to similarly treated high-risk T1 colon cancer (1.4%).…”

Significant polyps and early colorectal cancer: the importance of high‐quality standardized histopathology

“…There are a significant number of difficult cases that can be misinterpreted by the unwary, and displacement of adenomatous epithelium into the submucosa (pseudoinvasion) is particularly problematic. In a review of difficult cases in the NHS BCSP, 69% of lesions originally reported as malignant were downgraded to benign on expert review . For this reason, the NHS BCSP Pathology Committee have recommended that all cancers diagnosed in the programme should be reported by two independent pathologists, to reduce the risk of overtreatment .…”

Bioinformatics Analysis Reveals Most Prominent Gene Candidates to Distinguish Colorectal Adenoma from Adenocarcinoma

“…It can be the result of a torsion or intraluminal trauma of large pedunculated polyps of the distal colon, or it may be a consequence of a previous biopsy. Adenomas with epithelial misplacement (pseudoinvasion) can be difficult to distinguish from adenomas with early adenocarcinoma [ 5 – 7 ]. The correct diagnosis is crucial for the choice of optimal treatment.…”

“…The correct diagnosis is crucial for the choice of optimal treatment. For adenoma and adenoma with epithelial misplacement, endoscopic removal is sufficient, whereas malignant adenomas (early carcinomas) may require surgical treatment, since they are capable of metastasizing [ 7 ].…”

“…Despite well-defined morphologic features of epithelial misplacement and early invasion, there are a significant number of lesions with ambiguous features leading to divergent diagnostic opinions among pathologists [ 7 ]. Biomarkers that would enable to distinguish between adenoma with epithelial misplacement (pseudoinvasion) and adenoma with early adenocarcinoma (true invasion) are needed.…”