In a histologic study of the EGJ in 44 resection specimens for gastric cardiac cancer in Chinese patients, among which the entire EGJ was examined microscopically in 31 cases, Fan et al (23) used the most distal end of squamous mucosa, along with deep esophageal glands and ducts, as the histologic landmarks of the mucosal EGJ.
Recent histopathologic studies have characterized the morphologic features of the mucosal EGJ and defined the following histologic features of the mucosal EGJ as the distal ends of (1) squamous mucosa or islands (Figure 4); (2) deep esophageal glands and ducts (Figure 5); (3) multilayered epithelium (Figure 6) and hybrid glands; and (4) double-layered muscularis mucosa.
Squamous mucosa and deep esophageal glands and ducts are unique to the esophagus and absent in the stomach.
At present, the best histologic markers of the mucosal EGJ are the distal ends of (1) squamous epithelium, (2) deep esophageal glands and ducts, and (3) multilayered epithelium.
Srivastava et al (32) evaluated mucosal biopsy samples from 20 patients with Barrett esophagus and 20 patients with intestinal metaplasia of the gastric cardia; they found that intestinal metaplasia subjacent to squamous epithelium, intestinal metaplasia confined to the superficial mucosa, and presence of esophageal glands
or ducts were only seen in samples from patients with Barrett esophagus (with sensitivity of 57%, 40%, and 30%, respectively).