Mills Ch22 Stomach

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CHAPTER 22:  Stomach

Occasional cystic glands may be found in the cardiac mucosa but usually are not encountered in the pyloric mucosa. The cells of the mucus glands have ill-defined borders and a bub- bly cytoplasm that is different from the foveolar and surface epithelia. They resemble Brunner glands of the duodenum. Isolated parietal cells are not infrequently found either sin- gly or in small groups, particularly in the pyloric mucosa and especially at the junctional zone, where it meets the oxyntic mucosa (1). However, it is uncommon for zymogenic (chief) cells to be present outside of the oxyntic mucosa and junc- tional area. The pyloric glands secrete neutral mucin only. The cardiac glands secrete predominantly neutral mucin with small amounts of sialomucin (9). The extent of the cardiac mucosa and even its existence as a component of the normal GEJ have been disputed. Chandrasoma et al. (10) studied the gastroesophageal region in unselected adult autopsies. They found that when one histologic section was taken through this region, only 27% of cases had a zone of pure cardiac mucosa, 44% of cases had a zone of cardiofundic mucosa (glands containing a mixture of mucus-secreting cells and parietal cells), and 29% of cases had only pure oxyntic mucosa. When the entire GEJs from a selected group of adult autopsies were examined, all cases had cardiofundic mucosa present, but only 44% had a zone of pure cardiac mucosa. They also found that the zones of pure cardiac and cardiofundic mucosae were incomplete so that in some sections the esophageal squamous epithelium was present immediately adjacent to pure oxyntic mucosa. The average length of the cardiac and cardiofundic mucosae was 5 mm, and it never extended beyond 15 mm from the lower margin of the squamous esophageal epithelium. Other investigators have obtained similar results (11). In contrast, Kilgore et al. (12) and Zhou et al. (13) examined autopsy material from fetuses, infants, and young children. They found that pure cardiac mucosa was present in every case and measured 1.0 to 4.0 mm in length (average 1.8 mm). In 38% of cases, there was an abrupt transition from cardiac to oxyntic glands and in the remainder of cases, an additional zone of cardiofundic mucosa was present that generally mea- sured less than 1.0 mm in length. In all instances where car- diofundic mucosa was present, it was in addition to a zone of pure cardiac mucosa. These findings suggest that pure car- diac mucosa and cardiofundic mucosa are normal findings but the extent of the mucus-secreting mucosa is less than was previously thought. However, note that the term cardia refers to a loosely defined gross anatomical zone. The cardia is therefore larger than the zone of pure cardiac mucosa and may contain cardiofundic and pure oxyntic mucosa. Cardiac mucosal abnormalities may occur when there is gastroesophageal reflux or when the stomach is infected by Helicobacter pylori. The changes may include inflam- matory nuclear atypia, intestinal metaplasia (IM), and the presence of hybrid mucosa (14). Hybrid mucosa is multi- layered, with squamous cells at the base of the mucosa and columnar epithelium on the surface. With the development of these inflammatory changes, it may be difficult or even

impossible to distinguish between damaged cardiac mucosa and glandular metaplasia of esophageal squamous epithe- lium (Barrett esophagus). Reference to specialized pathol- ogy texts is required (15). This distinction has a practical importance because at the present time it appears that Barrett esophagus carries a higher potential for malignant change than does metaplastic cardiac mucosa (16). Oxyntic Gland Mucosa The oxyntic gland mucosa has foveolae that occupy less than one-quarter of the mucosal thickness. In contrast to the car- diac and pyloric mucosae, the glands are tightly packed and are straight rather than coiled (Fig. 22.9). For descriptive pur- poses, they can be divided into three portions: base, neck, and isthmus. The basal portion consists mainly of zymogenic cells (pepsinogen secreting). These are cuboidal and have a basally situated nucleus, which typically contains one or more small nucleoli and cytoplasm that usually stains pale blue–gray (basophilic) with some variation, depending on the type of hematoxylin used (Fig. 22.10). The bluish color of the cytoplasm is due to the presence of rough endoplasmic FIGURE 22.9  Gastric oxyntic mucosa. Note the short foveolae and the tightly packed glands. Purplish zymogenic cells predominate at the base, and pinkish parietal cells predominate in the upper part of the glands.

FIGURE 22.10  Oxyntic glands, showing parietal cell cytoplasm staining light pink and zymogenic cell cytoplasm staining purplish (H&E).