What type of mucosa is seen in Barrett's (Barrett's esophagus)?

Barrett's Esophagus: Mucosal Types

Barrett's esophagus is characterized by metaplastic columnar epithelium that replaces the normal squamous epithelium of the esophagus, and can present as either gastric-type metaplasia (cardiac or fundic) or intestinal metaplasia with goblet cells, with the latter being the most biologically unstable and carrying the highest cancer risk. 1, 2

Primary Mucosal Types

Barrett's esophagus encompasses three distinct types of columnar epithelium that can line the distal esophagus:

Intestinal Metaplasia (Specialized Columnar Epithelium)

• This is the most clinically significant type, characterized by the presence of acid mucin-containing goblet cells 1, 2
• Most commonly presents as incomplete (type II or III) intestinal metaplasia comprising mucous cells and goblet cells, though complete type (type I with absorptive cells) may also be seen 1
• Carries the highest risk of neoplastic progression, with an annual incidence of high-grade dysplasia and cancer of 0.38% compared to 0.07% in patients without intestinal metaplasia 1, 2
• Goblet cells can be confirmed using Alcian blue staining at pH 2.5, which highlights the acid mucins 1

Gastric-Type Metaplasia

• Barrett's esophagus can present with cardiac-type or fundic-type gastric epithelium without goblet cells 1, 2
• This type carries lower cancer risk than intestinal metaplasia, though the exact neoplastic potential remains incompletely defined 1
• The British Society of Gastroenterology recognizes "Barrett's esophagus with gastric metaplasia only" as a distinct diagnostic category 1, 2

Diagnostic Considerations

Histopathological Requirements

• The diagnosis requires synthesis of both endoscopic findings (≥1 cm columnar epithelium above the gastroesophageal junction) and histopathological confirmation of columnar metaplasia 2, 3
• Definitive esophageal origin can only be confirmed when columnar mucosa is seen juxtaposed with native oesophageal structures (submucosal glands, gland ducts), but these are present in only 10-15% of biopsy samples 1
• Multi-layered epithelium is considered pathognomonic for Barrett's esophagus 1

Controversy Regarding Intestinal Metaplasia Requirement

• The American Gastroenterological Association workshop in 2004 emphasized that intestinal metaplasia documented by histology should be a prerequisite criterion for diagnosis, given that dysplastic epithelium arising in cardiac or fundic mucosa without coexisting intestinal metaplasia appears uncommon 1
• However, more recent British Society of Gastroenterology guidelines (2014) recognize Barrett's esophagus with gastric metaplasia only as a valid diagnosis, acknowledging that the neoplastic risk of cardiac and fundic-type mucosa is not fully known 1, 2

Clinical Pitfalls

A critical caveat is that metaplastic esophageal columnar epithelium without visible goblet cells may still show phenotypic evidence of intestinal differentiation on immunohistochemical staining 4. This suggests that squamous epithelium may convert initially to nongoblet columnar epithelium before developing goblet cell metaplasia, representing a continuum rather than distinct entities 4.

The distinction between true Barrett's esophagus and intestinal metaplasia of the gastric cardia cannot be made reliably on histology alone in most cases and requires careful endoscopic correlation with precise documentation of biopsy sites relative to anatomic landmarks 1.