The Histopathology of Treated Barrett's Esophagus

Abstract

Columnar metaplasia of the lower esophageal epithelium (Barrett's esophagus) occurs in response to acid reflux, and its most important long-term complication is malignancy. In view of this, techniques are being explored for the eradication of Barrett's esophagus, and histopathologists will increasingly be required to assess response to these therapies in esophageal biopsy samples. The histopathologic features before and after treatment were studied in biopsy samples from 16 patients receiving omeprazole only, 10 treated by KTP laser photoablation, and five who underwent photodynamic therapy. All the treatment modalities resulted in histologic changes with at least partial squamous reepithelialization of the metaplastic columnar epithelium. The histologic findings suggest three main mechanisms for this: encroachment of adjacent squamous epithelium at the squamocolumnar junction, extension of epithelium from the submucosal gland duct to form squamous islands, and squamous metaplasia within the Barrett's columnar mucosa itself. The latter mechanism implies the existence of pluripotential stem cells within Barrett's mucosa. A relatively common finding was residual glandular mucosa, nonneoplastic and dysplastic, beneath squamous epithelium indicating the requirement for histologic confirmation of endoscopically suspected complete squamous reepithelialization with sufficiently deep biopsies.

Buried Metaplasia After Endoscopic Ablation of Barrett's Esophagus: A Systematic Review

“…It is possible that metaplastic glands grow underneath squamous epithelium spontaneously at squamo-columnar junction areas. It also has been proposed that, as a consequence of extensive biopsy sampling of metaplastic epithelium during endoscopic surveillance, the esophageal biopsy sites heal via growth of neosquamous epithelium that buries metaplastic glands (15,16). Biopsy-induced regrowth of squamous epithelium is presumed to be the origin of “squamous islands” that are found frequently in Barrett's esophagus during endoscopic surveillance ( Figure 2 ).…”

Pathology of early invasive adenocarcinoma of the esophagus or esophagogastric junction

“…Another important feature in patients with IM is the potential presence of glandular mucosa underlying preexisting squamous epithelium, which was identified in 19% of our cases. Recent studies have shown the persistence of IM covered by squamous epithelium following endoscopic ablation by laser, 46 photodynamic therapy, 47 and argon plasma coagulation, 48 and in patients on medical acid suppressive therapy only. 49 Follow-up studies need to be awaited to establish the malignant potential of this concealed IM.…”

Role of Confocal Laser Endomicroscopy in Detection of Residual Barrett's Esophagus after Radiofrequency Ablation

“…This neosquamous epithelium thickens over time to a normal stratified squamous epithelium. Several theories exist as to the source of the neosquamous epithelium, including encroachment of adjacent squamous epithelium, extension of cells from the submucosal gland duct lining with conversion to squamous epithelium, and circulating pluripotent stem cells which deposit in the wound and transform to squamous stem cells [19, 20]. Biddlestone et al have reported that SSIM, when it occurs, resides in the deep portion of the epithelium or in the lamina propria [21].…”