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
  • 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
    • 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
  • 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
    • 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
  • 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
  • Rare serrated adenomas have been reported
    • Most are cardiac
    • High incidence of carcinoma
    • Not clear how they fit into above classification

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

Supplemental studies

Immunohistology

Differential Diagnosis

• Various types of gastric adenoma
• Adenocarcinoma
• Gastric hyperplastic polyp
• Gastric hyperplastic polyp with reactive atypia
• Brunner gland adenoma
• Esophageal submucosal gland duct adenoma vs intestinal type adenoma
• Esophageal submucosal gland duct adenoma vs pyloric type adenoma

• Adenocarcinoma is defined by the presence of invasion into lamina propria or deeper

Bibliography

• Bosman FT, Carneiro F, Hruban RH, Thiese ND (Eds). WHO Classifiication of Tumors of the Digestive System, IARC, Lyon 2010
• Park YD, Lauwers GY. Gastric polyps: classification and management. Arch Pathol Lab Med. 2008 Apr;132(4):633-40.
• Oberhuber G, Stolte M. Gastric polyps: an update of their pathology and biological significance. Virchows Arch. 2000 Dec;437(6):581-90.
• Abraham SC, Montgomery EA, Singh VK, Yardley JH, Wu TT. Gastric adenomas: intestinal-type and gastric-type adenomas differ in the risk of adenocarcinoma and presence of background mucosal pathology. Am J Surg Pathol. 2002 Oct;26(10):1276-85.
• Stolte M, Sticht T, Eidt S, Ebert D, Finkenzeller G. Frequency, location, and age and sex distribution of various types of gastric polyp. Endoscopy. 1994 Oct;26(8):659-65.
• Chen ZM, Scudiere JR, Abraham SC, Montgomery E. Pyloric Gland Adenoma: An Entity Distinct From Gastric Foveolar Type Adenoma. Am J Surg Pathol. 2008 Sep 30(2):186-193.
• Vieth M, Kushima R, Borchard F, Stolte M. Pyloric gland adenoma: a clinico-pathological analysis of 90 cases. Virchows Arch. 2003 Apr;442(4):317-21.
• M'sakni I, Rommani SR, Ben Kahla S, Najjar T, Ben Jilani S, Zermani R. Another case of serrated adenoma of the stomach. J Clin Pathol. 2007 May;60(5):580-1.
• Ueyama H, Yao T, Nakashima Y, Hirakawa K, Oshiro Y, Hirahashi M, Iwashita A, Watanabe S. Gastric adenocarcinoma of fundic gland type (chief cell predominant type): proposal for a new entity of gastric adenocarcinoma. Am J Surg Pathol. 2010 May;34(5):609-19
• Singhi AD, Lazenby AJ, Montgomery EA. Gastric adenocarcinoma with chief cell differentiation: a proposal for reclassification as oxyntic gland polyp/adenoma. Am J Surg Pathol. 2012 Jul;36(7):1030-5.