Adenomatous Polyps of the Stomach
Definition
- Circumscribed benign epithelial neoplasm of the stomach
Note: Flat circumscribed dysplasia is best considered as a flat adenoma, which appears (at least largely) to be of intestinal type, and is included here
Diagnostic Criteria
- Three distinct types of gastric adenomas have been described and a fourth (oxyntic) proposed
- Notes:
- Much of the literature lumps all adenomas together and is thus dominated by the intestinal type, which constitutes more than half of gastric adenomas
- All may be tubular or villous or mixed
- Flat and depressed adenomas have been described in limited numbers
- Appear to be largely, if not all, intestinal type (see below)
- Goblet cells, Paneth cells and surface orientation in most cases described or illustrated
- High incidence of carcinoma
- Appear to be largely, if not all, intestinal type (see below)
- Intestinal type – most common
- Contains focal goblet cells or Paneth cells
- Elongate hyperchromatic nuclei
- Dysplastic features predominantly involved and accentuated towards the surface
- Associated with background of atrophic gastritis and intestinal metaplasia
- No association with familial adenomatous polyposis (FAP)
- High incidence of carcinoma
- 45% have high grade dysplasia
- 25% have invasive carcinoma
- Foveolar type
- Lined exclusively by gastric type foveolar cells with apical mucin caps
- PAS/d +, Alcian Blue –
- No goblet cells or Paneth cells
- PAS/d +, Alcian Blue –
- Elongate hyperchromatic nuclei
- Frequently associated with familial adenomatous polyposis (FAP)
- Usually 2 or 3 adenomas
- (Most of the gastric polyps in FAP are fundic gland polyps)
- No association with background of chronic gastritis or intestinal metaplasia
- High grade dysplasia and carcinoma rarely if ever present
- Lined exclusively by gastric type foveolar cells with apical mucin caps
- Pyloric gland type
- Closely packed pyloric gland tubules with frequent cystically dilated tubules interspersed
- Spread throughout the polyp, not surface oriented like other adenomas
- PAS/d and Alcian Blue negative
- No apical mucin cap or goblet cells
- Frequently has ground glass cytoplasm
- Usually short columnar cells
- Nuclei generally small and round
- About 1/3 show no dysplastic cytologic features
- Round basal nuclei
- About 10% show mild dysplastic features
- Slight elongation and hyperchromasia of nuclei
- Slight nuclear pseudostratification
- About 40% show high grade dysplasia
- Large round nuclei with enlarged nucleoli
- Loss of polarity
- Glands may be complex and cribriform
- About 10% have intramucosal or invasive carcinoma
- About 1/3 show no dysplastic cytologic features
- Associated with background atrophic gastritis and intestinal metaplasia
- No association with familial adenomatous polyposis (FAP)
- 64% located in fundus
- Remainder of gastric lesions scattered evenly in other regions
- 15% in extra-gastric sites usually in patches of gastric heterotopic epithelium
- Duodenum, bile duct, gall bladder
- Closely packed pyloric gland tubules with frequent cystically dilated tubules interspersed
- Oxyntic gland polyp/adenoma
(proposed entity, Singhi 2012)
- Clustered glands and cords of oxyntic mucosa
- Lined by mucus neck, chief and parietal cells
- Wisps of smooth muscle between clusters
- Centered in deep mucosa
- Located in fundus or cardia
- Lacks significant pleomorphism, mitotic activity, necrosis, desmoplastic response and vascular invasion
- Earlier reports considered this to be "adenocarcinoma with chief cell differentation / fundic gland type" (Ueyama 2010)
- No recurrences or metastases reported
- Clustered glands and cords of oxyntic mucosa
- Rare serrated adenomas have been reported
- Most are cardiac
- High incidence of carcinoma
- Not clear how they fit into above classification
- Notes:
| Adenoma Type | Nuclei | Cytoplasm | Mucin | Assoc | Carcinoma/HGD |
| Intestinal | Elongated, hyperchromatic | Focal GC and PC | Goblets positive,MUC2+5-6- | Gastritis and IM | High |
| Foveolar | Elongated, hyperchromatic | Apical mucin cap | PAS+, AB+, MUC2-5+6- | FAP | None |
| Pyloric | Round, may be bland or atypical | Ground glass | PAS-AB- MUC2-5+ 6+ | Gastritis and IM | High |
| Oxyntic | Round, bland | Varies with cell type | MUC2-5-6+ | None | None |
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342
Original posting/updates: 11/29/09, 11/26/11, 12/25/12
