Accuracy of identification of tissue types in endoscopic esophageal mucosal biopsies used for molecular biology studies.

Objectives: To determine if histopathologic assessment of esophageal biopsies harvested for research study is justifi ed due to the heterogeneity of tissues in the esophagus, and the consequent histopathologic mis-matches with the clinical histopathology of biopsies taken at the same level. Methods: Since 2004, patients undergoing upper endoscopy for a variety of clinical conditions were invited to provide additional esophageal biopsies; those were collected for research purpose at the same level as biopsies collected for clinical histopathology. Research biopsies were cut in two parts: one part was submitted to research histopathology and the other stored for molecular analysis. Results of clinical histopathology for each patient were summarized per biopsy level and compared to results obtained from research biopsies at the corresponding level. Results: A total of 377 level summaries were obtained from 137 patients. Clinical histopathology summaries classifi ed 123 levels (32.6%) as squamous epithelium, 84 levels (22.3%) as metaplastic columnar-lined epithelium, 135 levels (35.8%) as columnar-lined epithelium with intestinal metaplasia, 30 levels (8%) as dysplasia, and 5 levels (1.3%) as adenocarcinoma. Research histopathology matched to clinical summaries on 120 of 123 (97.5%) levels for squamous epithelium, 52 of 84 (61.9%) for metaplastic columnar-lined epithelium, and 94 of 135 (69.5%) for columnar-lined epithelium with intestinal metaplasia. There were no matches for dysplasia between the groups; however, they agreed on all fi ve cases of AC. On 59 (70.2%) metaplastic columnar-lined epithelium levels and on 62 (46%) columnar-lined epithelium with intestinal metaplasia levels, tissue heterogeneity was observed in clinical histopathology, with portions of squamous epithelium within the samples. Matches with pure tissue samples in both clinical and research histopathology levels were observed on 22 (26.2%) levels of metaplastic columnar-lined epithelium and in 55 (40.7%) levels of columnar-lined epithelium with intestinal metaplasia. Conclusions: The high proportion of mismatches and tissue heterogeneity observed, especially among columnar-lined epithelium with intestinal metaplasia and dysplasia, points to the necessity of determining the histopathology of the research samples to avoid sampling errors during molecular studies.