1. NEOPLASMS OF THE STOMACH
Benign
Epithelial
Mesenchymal
Malignant
Lymphoma
Carcinoid

2. Tumors of the Stomach
Tumors arising from the mucosa predominate over mesenchymal tumors.
These are classified into polyps and carcinoma.
The term “polyp” is applied to any nodule or mass that projects above the level of surrounding mucosa
The use of the term “polyp” in GI tract is generally restricted to mass lesions arising in the mucosa.

3. NEOPLASMS OF THE STOMACH
Benign
Epithelial
hyperplastic polyps
Fundic gland polyps
Adenomatous polyps.
Mesenchymal
Malignant
Lymphoma
Carcinoid

4. Benign Neoplasms of Stomach
Mucosal polyps
Epithelial polyps are rare. (0.4%)
Types:
1] hyperplastic polyps; (80% to 85%
2] Fundic gland polyps (∼10%)
3] Adenomatous polyps (∼5%)
Appear as sessile or small pedunculated lesions, often multiple that can be removed endoscopically.
All three types arise in patient with chronic gastritis.
Large polyps are very rare.
- The risk of carcinoma is moderate in adenomatous polyp, slight in hyperplastic polyp, and nil in fundic gland polyps.

5. Adenomatous polyp of the stomach
Adenomatous polyp of the stomach. Note the large size of the polyp and its lobulated configuration. A small ulceration ( arrow) can be identified on its surface.

6. Malignant neoplasm of stomach
Carcinoma – 90-95%
Lymphoma – 4%
Carcinoids – 3%
Malignant spindle cell – 2%

7. Gastric carcinoma is the second leading cause of cancer-related deaths in the world, with a widely varying geographic incidence.

8. Malignant neoplasm of stomach
Gastric adenocarcinoma
Epidemiology
The incidence of gastric carcinoma is five to ten times higher in Japan than in the United States. It is also high in China and Chile.

9. There are two patterns Intestinal type and Diffuse type.
Intestinal type
occur on top of ch. Gastritis and intestinal metaplasia and common in high risk population after age 50 with 2:1 male predominance
Diffuse type
arise de novo in younger age group with with female predominance
In the United States, the incidence of Intestinal type had declined since 1950

10. Gastric adenocarcinoma
Risk factors for Gastric Carcinoma
Intestinal type adenocarcinoma
Diet
Nitrites
Smoked foods
Excessive salt
Decreased intake of fresh vegetables and fruits
Ch. Gastritis and intestinal metaplasia
Infection by H. pylori
Pernicious anemia
Altered anatomy
Diffuse Carcinoma
Undefined, E- cadherine (50%), FGFR2 (33%)

11. Amplification of HER-2/NEU and increased expression of β-catenin are present in 20% to 30% of cases and are absent in diffuse carcinoma

12. Malignant neoplasm of stomach
Gastric Carcinoma
Precancerous lesions ( intestinal type)
1. Chronic atrophic gastritis associated
with pernicious anemia.
2. Chronic atrophic gastritis associated
with helicobacter pylori infection.
3. Those with adenomatous and hyperplastic polyps.
4. Following subtotal gastrectomy.

13. Malignant neoplasm of stomach
Gastric carcinoma
Site:
- pylorus and antrum – 50-60%
- cardia – 25%
- body and fundus %
lesser curvature 40%
Greater curvature 12%
a favored location is the lesser curvature of the antropyloric region

14. Malignant neoplasm of stomach
Gastric carcinoma
Divided into:
1. Early gastric cancer (lesion limited to mucosa and submucosa)
– appears as a small, flat mucosal thickening that may have a minimal polypoid and ulcerative component.
2. Late gastric cancer
– defined as a gastric carcinoma that has invaded the muscle wall.
It may present in various ways:
- As a fungating mass that protrudes into the lumen.
- As a diffusely infiltrating lesion that causes thickening and contraction of the stomach wall with relatively little mucosal involvement (linitis plastica, or leather-bottle stomach).
- As a malignant ulcer (excavated) with raised, everted edges.

15. Malignant neoplasm of stomach

16. Malignant neoplasm of stomach
Any gastric ulcer that does not heal as expected should be biopsied to rule out carcinoma.

17. Gastric carcinoma
Intestinal type

18. The diffuse variant of gastric carcinoma
Arise de novo from native gastric-type mucous cells that generally do not form glands but rather permeate the mucosa and wall as scattered individual “signet-ring” cells or small clusters in an infiltrative growth pattern.
There is no association with chronic gastritis
Poorly differentiated
It occurs at early ages with female predominance.
Risk factors undefined
Rare inherited mutation of E-cadherin leading to autosomal dominant inheritance.
Mutations in FGFR2, a member of the fibroblast growth factor receptor family, and increased expression of metalloproteinases are present in about one-third of cases, but are absent in intestinal-type carcinomas.

19. Gastric carcinoma
Diffuse variant
Intestinal type

20. Malignant neoplasm of stomach
Spread of Gastric carcinoma
Direct:
Invades through the muscle wall into the omental fat.
Spread of tumor cells in the peritoneal fluid.
Spread to the ovary (Krukenberg’s tumor) and rectovesical pouch.
Lymphatic metastasis
to lymph nodes around the stomach
Left supraclavicular node (Virchow’s node)
Lymph node metastases are present in about 50% of cases at the time of diagnosis
Blood stream spread to the liver and lung

21. Malignant neoplasm of stomach
Clinical Features of Gastric carcinoma
Early gastric cancer:
asymptomatic
Late gastric cancer:
Resembling chronic peptic ulcer
Anorexia, anemias, weight loss, hematemesis and melena.
Tumors near the pylorus may cause gastric outlet obstruction.

22. Malignant neoplasm of stomach
Prognosis of Gastric carcinoma
The prognosis depends on the depth of invasion of the neoplasm.
Early cancer % years survival
Muscle wall invasion – 30% - 5 years survival
Full thickness invasion and lymph node – 5% - 5 year survival
Histologic features and differentiation are of little prognostic importance.

23. Malignant neoplasm of stomach
Malignant lymphoma
Two common types occur:
a. Low-grade malignant lymphoma arising in mucosa- associated lymphoid tissue (MALT lymphoma).
b. High-grade aggressive B cell lymphomas, most commonly B immunoblastic lymphoma.
Present as polypoid masses, ulcers, thickened fold.
MALT lymphoma restricted to can be cured by surgical resection ( more likely to be associated with H. pylori)
High grade lymphomas respond to chemotherapy, and
have a 5 year survival rate of about 60%.

24. Malignant neoplasm of stomach
3. Malignant gastric stromal neoplasms
Commonest mesenchymal neoplasm (2% of gastric malignancies)
Arise from undifferentiated mesenchymal cells in the gastric wall with ulceration.
Present as large masses that originate in and involve the wall with ulceration.
Composed of spindle cells that show varying cellularity, pleomorphism and mitotic activity
with smooth muscle or neural
differentiation.
Treatment: Surgical resection
over 50% survive 5 years.

25. Malignant neoplasm of stomach
Carcinoid tumors
- extremely rare.
- give metastasis in 30% of cases.

26. Summary of Gastric Tumors
More than 90% of gastric tumors are carcinomas;
lymphomas, carcinoids and stromal tumors are relatively infrequent.
The two main types of gastric adenocarcinomas are the intestinal and diffuse types; macroscopic patterns of both types may be exophytic, flat or depressed, or excavating.
Intestinal type of adenocarcinoma is associated with chronic gastritis caused by H. pylori infection, with gastric atrophy and intestinal metaplasia; composed of malignant cells forming intestinal glands.
Diffuse type of adenocarcinoma is not associated with H. pylori infection; composed of gastric type of mucous cells (signet ring cells) that permeate the mucosa without forming glands.