Gastric Tumors Lecture

A set of question-and-answer flashcards covering gastric polyps, adenomas, carcinomas, lymphomas, neuroendocrine tumors, and gastrointestinal stromal tumors as discussed in the lecture.

What proportion of upper-GI endoscopies reveal gastric polyps?

Up to 5 % of procedures.

Which three basic processes can give rise to gastric polyps?

Epithelial or stromal hyperplasia, inflammation, and neoplasia.

Which gastric polyp type is most common, and what percentage does it represent?

Hyperplastic/inflammatory polyps; 80–90 % of gastric polyps.

At what age are hyperplastic or inflammatory gastric polyps most frequently detected?

Between 50 and 60 years of age.

With which underlying gastric condition are hyperplastic/inflammatory polyps usually associated?

Chronic gastritis.

Describe the typical gross appearance of a hyperplastic gastric polyp.

Multiple, ovoid lesions < 1 cm, smooth-surfaced, often centrally umbilicated.

List two key microscopic features of hyperplastic gastric polyps.

Cystically dilated, elongated foveolar glands and edematous lamina propria with inflammatory infiltrate.

Are dysplastic changes common in hyperplastic gastric polyps?

No—dysplasia is not typically present.

Name three settings in which fundic gland polyps may develop.

Sporadic cases, familial adenomatous polyposis (FAP), or long-term proton-pump-inhibitor therapy.

Do fundic gland polyps have neoplastic (malignant) potential?

No—they are considered non-neoplastic.

What pathophysiologic sequence links proton-pump inhibitors to fundic gland polyps?

Reduced gastric acidity → hypergastrinemia → gastrin-driven glandular hyperplasia.

Where in the stomach are fundic gland polyps typically located?

Predominantly in the body and fundus.

Which cell types line the dilated glands of fundic gland polyps?

Parietal, chief, and mucous neck cells.

Approximately what fraction of gastric polyps are adenomas?

About 10 %.

Which sex shows a higher incidence of gastric adenomas, and by what ratio?

Males, at roughly a 3 : 1 ratio over females.

Which inherited condition markedly increases the risk of gastric adenomas?

Familial adenomatous polyposis (FAP).

On what mucosal background do most gastric adenomas arise?

Chronic gastritis with atrophy and intestinal metaplasia.

What is the estimated risk of carcinoma within a gastric adenoma, and what factor influences it most?

≈ 30 % risk, correlated with increasing lesion size.

In which gastric region are adenomas most commonly found?

The antrum.

Name the two epithelial subtypes of gastric adenoma.

Gastric-type and intestinal-type (the latter is more common).

How are gastric adenomatous polyps classified morphologically?

Tubular (adenomatous), tubulovillous (villoglandular), and villous adenomas.

What histologic feature distinguishes low-grade from high-grade dysplasia in gastric adenomas?

Low-grade retains nuclear polarity; high-grade shows loss of polarity with cribriform/complex architecture.

Rank the four main malignant tumors of the stomach by frequency.

Carcinoma (90–95 %) > lymphoma (~4 %) > carcinoid (3 %) > stromal tumors (2 %).

According to the Lauren classification, what are the two main types of gastric adenocarcinoma?

Intestinal-type and diffuse-type.

Describe the classic gross appearance of diffuse-type gastric carcinoma.

Infiltrative thickening of the wall producing linitis plastica (“leather-bottle” stomach).

List four risk factors for intestinal-type gastric adenocarcinoma.

Chronic gastritis with intestinal metaplasia, Helicobacter pylori infection, dietary nitrites/smoked or pickled foods/high salt, low intake of fresh fruits & vegetables, and prior partial gastrectomy.

Which inherited genetic defect predisposes to diffuse-type gastric carcinoma?

Germline mutation in the E-cadherin (CDH1) gene.

Name the four histological patterns of gastric carcinoma recognized by the WHO.

Papillary, tubular, mucinous, and signet-ring-cell types.

Which histological subtype of gastric carcinoma is characterized by pools of extracellular mucin with floating tumor cells?

Mucinous (colloid) carcinoma.

What is the most common subtype of primary gastric lymphoma, and with which infection is it linked?

Extranodal marginal zone B-cell lymphoma of MALT; strongly associated with H. pylori infection.

What microscopic finding is characteristic of MALT lymphoma in the stomach?

Lymphoepithelial lesions (neoplastic lymphocytes infiltrating and destroying gastric glands).

From which cell lineage do gastric neuroendocrine tumors arise?

Cells of the diffuse neuroendocrine system (e.g., enterochromaffin-like cells).

Name three conditions that may be associated with gastric neuroendocrine tumors.

Endocrine-cell hyperplasia, chronic atrophic gastritis, and Zollinger-Ellison syndrome.

What is the most common mesenchymal tumor of the abdomen?

Gastrointestinal stromal tumor (GIST).

From which cells are GISTs believed to originate?

Interstitial cells of Cajal located in the muscularis propria.

Approximately what proportion of GISTs harbor activating c-KIT mutations?

About 75–80 %.

Which two immunohistochemical markers are most useful for diagnosing GIST?

c-KIT (CD117) and CD34.

What are the two principal microscopic growth patterns seen in GIST?

Spindle-cell type and epithelioid type.