Polyps in general: is a descriptive term of forming a mass that is exophytic & polypoid.

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2 ميحرلا نمحرلا هللا مسب Gastric Tumors: Benign tumours & tumor-like conditions: -Mucosal: Gastric polyps (they are uncommon) -Mesenchymal tumours: Leiomyoma & Lipoma (can occur anywhere in the body) Malignant: -Gastric carcinoma in general or (gastric adenocarcinoma) (~90%) -Malignant lymphoma (5%) -Carcinoid tumor (3%); Arises from neuroendocrine cells (Lining contains neuroendocrine hyperplasia forming carcinoid tumour in Autoimmune gastritis) -Gastrointestinal stromal tumor, GIST(2%) ; A mesenchymal tumor that arises from Cells of Cajal Types of Gastric Polyps: they are uncommon Cells of cajal: They have a neurological function and muscular properties Polyps in general: is a descriptive term of forming a mass that is exophytic & polypoid. Divided to: Neoplastic (there is recurrent genetic abnormality) and Non-Neoplastic (no recurrent genetic abnormality so the eitology of them might be inflammatory such as Hyperplastic polyps) Hyperplastic (inflammatory) polyps (~75%) in Stomach -Non-neoplastic -Not true neoplasms exuberant response to chronic gastritis -Localized edema & collection of inflammatory cells -Hyperplastic mucosal epithelium and an inflamed edematous stroma. Fundic gland polyps ( 10%) -Neoplastic, But it doesn t have potential of progression into carcinoma (gastric adenocarcinoma) -Small collections of dilated corpus-type glands. -May occur due to excessive use of Proton pump inhibitor (PPIs) 1

3 -May occur in persons with Familial adenomatous polyposis (FAP) *persons with innumerable polyps in colon (Adenomatous) or in Stomach (Fundic gland polyp) that arise from funds, they are cystic dilated glands) Adenomatous polyps ( 10%). To call it adenomatous there must be dysplasia, this applies for the whole GIT - True neoplasm - Contain dysplastic epithelium - Risk of malignant transformation with polyp size >2cm. Gastric Carcinoma (malignant) Invasive & deadly Epidemiology: - High incidence in Japan, southern Korea, Chile (they consume lots of smoked food) - Low Socioeconomic groups. - There is a steady decline in overall incidence and mortality due to proper screening programs and awareness, especially in areas with high incidence (except CA OF CRDIA). -Poor prognosis Classification of gastric carcinoma WHO classification -Adenocarcinoma: * intestinal type * diffuse type -Papillary Adenocarcinoma: depends on architecture -Tubular Adenocarcinoma: forming a small, uniform tubule -Mucinous Adenocarcinoma: produces mucin, pools of mucin in between them malignant cells -Signet ring Adenocarcinoma: cells resemble signet ring 2

4 -Adenosquamous Carcinoma: combined Adenomatous, containing two types of cells ( Adeno carcinoma & squamous cell carcinoma) -Squamous cell carcinoma -Undifferentiated carcinoma: the cells are very immature and primitive, we can t determine if it s adenocarcinoma or squamous cell carcinoma in origin Adenocarcinoma Intestinal type -The more common type in high risk population -Age of 50Y -M > F - H.pylori in stomach cause Intestinal metaplasia Then dysplasia then intestinal type of adenocarcinoma - Usually Arises in background of chronic gastritis caused by H.pylori (Most common) -Usually form a Bulky mass -Form glands similar to intestine Better differentiated Diffuse type - Less common. - Uniform incidence among population - earlier age - M = F - Arise de novo from native gastric mucous cell - Not associated with chronic gastritis -infiltration to the wall, usually submucosal -No definite mass. -May lead to hardening of the wall (Lintis Plastica) -doesn t form glands -single cells in stroma Poorly differentiated 3 Well-differentiated cancer cells look more like normal cells and tend to grow and spread more slowly than poorly differentiated or undifferentiated cancer cells. Differentiation is used in tumor grading systems, which is different for each type of cancer.

5 Risk factors of adenocarcinoma - Intestinal type : Arises in background of chronic gastritis Infection with H.Pylori Diets containing foods that might generate nitrites that form nitrosamines & nitrosamides (smoked foods may inhibt nitrosation) Partial gastrectomy Pernicious anemia (Autoimmune gastritis) - Diffuse type risk factors are undefined Rare inherited mutation of E-Cadherin Infection with H.Pylori & chronic gastritis are often absent Morphology : -Location: Pylorus and antrum (50% to 60%) > Cardia (25%) > body & fundus. Lesser curvature > Greater curvature. Lesser curvature of the antropyloric region. - Classification based on depth of invasion: Important because prognosis & management is different. Early gastric carcinoma (non-invasive, in-situ): Confined to the mucosa & submucosa Advanced gastric carcinoma: Extended below the submucosa, all the way to the muscle layer 4

6 - Malignant ulcer forming mass lesion - This is opened stomach divided in half - Mucosa still intact, no ulceration or loss of mucosa but at same time there is still tumor infiltrating the wall under mucosa - Difficult to be detected by endoscopy ; due to mucosa still intact - We have to take deep biopsy to see the tumor Microscopic appearance The intestinal type: Malignant cells forming neoplastic glands resembling those of colonic adenocarcinoma. The diffuse type: - Composed of gastric-type cells invading the wall in infiltrative pattern (NO gland formation) - cells still intact, no ulceration - Some cells contain mucous signet-ring" cells because of mucin pushing nucleus aside to periphery. 5

7 Tumor spread Direct spread (mucosa submucosa muscle serosa) Regional and distant LNs (The earliest LN to be involved is the supraclavicular lymph node, by metastatic adenocarcinoma,(virchow node) Distant metastasis (mainly to liver) Intraperitoneal spread: In females may involve both ovaries (Krukenberg tumor). Malignant cells breached the serosa and reached the peritoneal cavity. It was then implanted on the outer surface of ovaries acquiring their blood supply forming Krukenberg tumor. Clinical Features Early gastric cancer: -Usually asymptomatic. -Abdominal discomfort, dyspepsia & nausea. Advanced carcinoma: -May be asymptomatic -Iron deficiency anemia (caused by chronic bleeding), anorexia, bleeding, and weight loss Tumors of the cardia may cause dysphagia, because it s close to the esophegous leading to obstruction Tumors of pylorus may cause gastric outlet obstruction (presented by: abdominal discomfort, feeling of in-digestion, after complete obstruction they will have recurrent vomiting). Prognosis Stage (TNM): Most important. -T: Depth of invasion -N: lymph node involved, number or location -M: presence or absence of metastasis Type: Signet ring & diffuse type carry a poor prognosis. 5year survival in: Early CA 90%. Advanced CA < 20%*. TNM: a cancer staging notation system that describes the stage of a cancer which originates from a solid tumor with alphanumeric codes. 6

8 Diseases of the small and large intestine - Developmental anomalies - Vascular disorders (ischemia) - Colonic diverticulosis (very common in above 50y) - Inflammatory bowel disease - Bowel obstruction - Malabsorption syndromes - Tumors Developmental anomalies - Meckel diverticulum (most common) - Atresia - Stenosis - Duplication - Omphalocele - Gastroschisis - Malrotation Now we will talk about them one by one. Atresia: Complete failure of development of the intestinal lumen. In other words: incomplete canalization in hollow organs which lead to blind ended lobe in the distal part, won t be connected to other parts. -Duodenal atresia is the most common of intestinal atresia Stenosis: - Narrowing of the intestinal lumen with incomplete or complete obstruction - May affect any segment of the intestine. Bowel Duplication - Well-formed saccular or tubular cystic structures (double lumen separated by a wall) -May or may not communicate with the lumen 7

9 Omphalocele - Abdominal musculature fails to form (muscle wall of abdomen fails to form), leading to herniation of abdominal contents into a ventral membranous sac Gastroschisis - A portion of muscle abdominal wall fails to form causing extrusion of intestine *Difference between Omphalocele & Gastroschisis Omphalocele has a sac that covers the organs Gastroschisi has no membrane so organs are exposed to the outer surface, increasing risk of infection & ischemia and these patients usually die Malrotation - Results from improper embryologic rotation of the gut. - Increased risk of twisting, containing redundant mesentery, at the same time there is anatomical abnormal blood supply to the intestine which will lead to increasing the risk of ischemia and twisting. (midgut volvulus) Meckel Diverticulum (true diverticule) - It is present in 2% of population. -True D. : containing all layers -False D. : only mucosa & sub mucosa without muscle wall - It results from failure (incomplete) of involution of the proximal portion of the vitelline (omphalomesenteric) duct. - More common in males 8

10 - 30% have other congenital anomalies including tracheoesophageal fistula. Pathology The usual location is in the distal ileum 80 cm proximal to the ileocecal valve Always on the antimesenteric border. Blind tubular pouch of variable length (1-8 cm) True diverticulum composed of all layers of the normal small intestine. The lining is of small intestinal type. May contain: Gastric, duodenal or colonic mucosa Clinical picture Generally asymptomatic. Bacterial overgrowth may lead to vitamin B12 deficiency (due to stasis of food contents) Heterotopic gastric mucosa may cause peptic ulcer in the adjacent intestinal mucosa leading to -Intestinal bleeding or -Symptoms resembling Acute appendicitis due to inflammation & infection. Also same location, connected to terminal ileum and the appendix connected to cecum, so they are in the same anatomical region related to each other. Edited by: Salam Mustafa Good Luck 9