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Stomach

Polyps

Adenomas

Reviewers: Elliot Weisenberg, M.D. (see Reviewers page)
Revised: 8 August 2012, last major update August 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.

General
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● 8-10% of all gastric polyps
● Flat and depressed adenomas may occur
● Relatively rare in Western populations; incidence increases with age, generally parallels that of gastric adenocarcinoma, M:F = 3:1
● Associated with autoimmune gastritis, intestinal metaplasia, familial adenomatous polyposis
● Considered to be analogous to colonic dysplasia-associated masses arising in setting of chronic inflammatory bowel disease, as they arise in a background of atrophic gastritis (metaplastic or autoimmune)
● Only rarely associated with reactive/chemical gastropathy or post-antrectomy

Prognostic factors
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● Precursor lesion of gastric adenocarcinoma
● Up to 30-40% contain focus of carcinoma at time of diagnosis, risk higher in larger tumors, especially if >2cm, flat or depressed
● Up to 30% risk of carcinoma in adjacent mucosa
● 3% progress to carcinoma in 7 years (higher risk of carcinoma than colonic adenomas)
● Intestinal type may have higher risk (Am J Surg Pathol 2002;26:1276)
● APC mutations, MSI may occur

Case reports
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● Paneth cell adenoma (Am J Surg Pathol 1989;13:325, Arch Pathol Lab Med 1989;113:129)

Treatment
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● Complete excision, biopsy of nonpolypoid antrum and body, endoscopic surveillance, H. pylori eradication

Gross description
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● Usually single, up to 4 cm, sessile or pedunculated
● Rarely are depressed mucosal lesions

Gross images
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Various images

Micro description
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● Polypoid projections of dysplastic epithelium (by definition) with pseudostratification, nuclear abnormalities, mitotic figures overlying cystically dilated glands without dysplastic changes
● Villous or tubular or both
● Contains scattered endocrine cells, Paneth cells
● Associated with atrophy and intestinal metaplasia

High grade:
● Cribriforming, irregularly shaped crowded glands with branching and budding and marked cytologic atypia

Intestinal type (majority):
● Focal goblet cells or Paneth cells
● More likely to show high grade dysplasia or adenocarcinoma within the polyp or a separate adenocarcinoma
● Associated with intestinal metaplasia and H. pylori gastritis

Gastric type:
● Lined entirely by gastric mucin cells on PAS/Alcian blue stain
● Distributed throughout stomach, 82% solitary, not associated with coexisting carcinoma, background mucosa usually normal

Indeterminate:
● Cannot determine due to lack of mucin production

Micro images
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Endoscopy and histology

Positive stains
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● CEA, p53

End of Stomach > Polyps > Adenomas

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