gastric hyperplastic polyp

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Definition: Gastric hyperplastic polyps are the most common epithelial polyps of the stomach and are found throughout the stomach, ranging in size from a few millimeters to centimeters. Hyperplastic polyps used to constitute from 75% to 90% of all gastric polyps.

They arise from the foveolar hyperplasia that frequently accompanies atrophic gastritis,whether ofthe multifocal or autoimmune type. They may also appear on the gastric side of gastroenterostomy stomas.

Patients with hyperplastic polyps are at increased risk of gastric cancer, but the cancers very rarely arise in them. Rather, they are byproducts of the chronic gastritis that is the underlying cause of cancer induction. In the unusual event that a cancer does arise in a hyperplastic polyp, it is preceded by the development of dysplasia.

The hyperplastic polyp is believed that they represent an exuberant regenerative response of gastric foveolar cells.

Diagnostic criteria for hyperplastic polyps included hyperplastic foveolae with variable amounts of inflamed stroma that formed an endoscopically identifiable polyp.

Etiology

Hyperplastic polyps develop in response to gastric injury such as from
HP infections or autoimmune gastritis or around gastric remnants, ulcers, or surgically created stomas. They may also develop in the proximal stomach in patients with chronic gastroesophageal reflux.

Localization

Most hyperplastic polyps develop in the gastric body and antrum. They may also develop in the proximal stomach in patients with chronic gastroesophageal reflux.

Macroscopy

Hyperplastic polyps are typically small, smooth, sessile lesions,measuring @<@2.0 cm in diameter.

Rare polyps are large (up to 13 cm) and simulate carcinoma. Larger polyps may appear lobulated and/or pedunculated, often with superficial erosions.

These may twist on their stalks, leading to superficial ulceration, hemorrhage, pyloric prolapse, or intermittent obstruction.

Microscopy

Diagnostic criteria for hyperplastic polyps included hyperplastic foveolae with variable amounts of inflamed stroma that formed an endoscopically identifiable polyp.

Most hyperplastic polyps arise on a background of chronic gastritis. Intestinal metaplasia (as part ofthe surrounding atrophic gastritis) may be present.

The glands do not normally participate in the formation of the polyps.

Two major features categorize hyperplastic polyps:

 The first is marked elongation, infolding, and branching of the gastric pits leading to a corkscrew or serrated appearance.

• Tall mucin-secreting foveolar cells line exaggerated, elongated, and distorted pits that extend from the surface deep into the stroma.
• Hypertrophic foveolar cells resembling goblet cells can be present.
• The pits also dilate to form variably sized and shaped cysts, which can be quite prominent.
• Glandular epithelium may befound in the deeper parts ofthe polyps.
• The glands are often antral in type, even when the polyps arise in the body or fundus. Occasionally one sees oxyntic glandular mucosa.

 The second major change is an excess ofan edematous stroma that is infiltrated by plasma cells, lymphocytes, eosinophils, mast cells, macrophages, and variable numbers of neutrophils.

• Smooth muscle fibers arborize in the lamina propria.

These lesions are highly vascularized. Vascular proliferations resembling granulation tissue develop superficially near areas of erosion.

The glands may acquire an apparent back-to-back configuration near areas of ulceration, but epithelial atypia is either absent or minimal and often regenerative in nature, especially in areas of surface erosion.

Neutrophils are prominent inulcerated areas.

Reparative changes can superficially resemble low-grade dysplasias or adenomas.

Synopsis

 The multiple cysts are present in an edematous stroma.
 Cystic glands lined by gastric mucous cells

Tumor predisposition

The polyps may contain areas of epithelial dysplasia, which may be high grade or low grade.

The prevalence of dysplasia ranges from 1% to 20% and is most frequently found in larger polyps.

Dysplastic changes are generally more extensive than the atypias seen in focally eroded polyps. These areas of dysplasia may give rise to invasive carcinomas. The overall malignant potential is probably @<@2%.

If dysplasia is found in a hyperplastic polyp at the time of biopsy, it is important to determine whether the dysplasia is confined to the hyperplastic polyp or is part ofa more diffuse neoplastic process.

If the lesion is confined to the polyp and the polyp has been removed by a polypectomy, then thelesion is likely cured.

Molecular pathology

The polyps may contain clonal ras mutations, in the neoplastic as well as the non-neoplastic regions.

Differential diagnosis

The differential diagnosis of hyperplastic polyps includes :
 Menetrier disease

• Menetrier disease is usually a more extensive process and has characteristic clinical features.

 juvenile polyposis

• The distinction from juvenile polyposis usually relies on the presence ofcolonic polyps and the clinical features.

 Cronkite-Canada syndrome

• The distinction from Cronkite-Canada syndrome may be very difficult, although it is a very rare disorder and does have characteristic ectodermal features.

Associations

 chronic gastritis

• autoimmune gastritis

 Helicobacter pylori-associated gastritis
 post-antrectomy stomach
 Gastric neuroendocrine cell hyperplasia and type 1 tumors (23011644)

See also

 gastric anomalies

• gastric tumors
  • gastric polyps

References

 Gastric neuroendocrine cell hyperplasia and type 1 tumours occurring within gastric hyperplastic polyps. Chetty R, Gill P, Mugon P, Shrimankar J, Hughes C. Virchows Arch. 2012 Sep 26. PMID: 23011644

 Abraham SC, Singh VK, Yardley JH, Wu TT. Hyperplastic polyps of the stomach: associations with histologic patterns of gastritis and gastric atrophy. Am J Surg Pathol. 2001 Apr;25(4):500-7. PMID: 11257625