Observer variation in the diagnosis of superficial oesophageal adenocarcinoma

Background and aims: When to perform oesophagectomy for neoplastic progression in Barrett's oesophagus is controversial. Some resect for high grade dysplasia whereas others defer treatment until intramucosal adenocarcinoma is diagnosed. Interobserver agreement for a diagnosis of high grade dysplasia or intramucosal adenocarcinoma remains unknown and may have therapeutic implications. Methods: Histological slides from 75 oesophagectomy specimens with high grade dysplasia or T-1 adenocarcinoma were blindly reviewed by two gastrointestinal pathologists and one general surgical pathologist, and classified as high grade dysplasia, intramucosal adenocarcinoma, or submucosal adenocarcinoma. A subsequent re-review of all 75 cases by the same observers following establishment of uniform histological criteria was undertaken. Interobserver agreement was determined. by kappa statistics. Coefficients <0.21, 0.21-0.40, 0.41-0.60, 0.61-0.80, and >0.80 were considered poor, fair, moderate, good, and very good agreement, respectively. Results: Interobserver agreement among all pathologists and between gastrointestinal pathologists when comparing high grade dysplasia with intramucosal adenocarcinoma was only fair (k=0.42; 0.56, respectively) and did not substantially improve on subsequent re-evaluation following establishment of uniform histological criteria (K=0.50; 0.61, respectively). Conclusions: When evaluating resection specimens and after implementation of uniform histological criteria, even experienced gastrointestinal pathologists frequently disagree on a diagnosis of high grade dysplasia versus intramucosal adenocarcinoma. Treatment strategies based on the histological distinction of high grade dysplasia from intramucosal adenocarcinoma using limited biopsy specimens should be re-evaluated.