IUHS Student-2-Student USMLE Step 1 Recall

                                                        GI Tract

                                                        Stomach

Pyloric Stenosis

infants as a disorder that affects boys three to four times more often than girls, occurring in 1 in 300 to 900 live births...

 familial occurrence implicates a multifactorial pattern of inheritance; monozygotic twins have a high rate of concordance of the condition...pyloric stenosis also may occur in association with turner syndrome, trisomy 18, and esophageal atresia...

 regurgitation and persistent projectile,

nonbilious vomiting usually appear in the

second or third week (can appear up to the fifth week) of life...physical examination reveals visible peristalsis and a firm, ovoid palpable mass in the region of the pylorus or distal stomach, the result of hypertophy, and possibly hyperplasia, of the muscularis propria of the pylorus...edema and inflammatory changes in the mucosa and submucosa may aggravate the narrowing...surgical muscle splitting is curative...

 boys are at a greater risk for this disease if their mother had it...

 acquired pyloric stenosis in adults is one of the long term risks of antral gastritis or peptic ulcers close to the pylorus...carcinomas of the pyloric region, lymphomas, or adjacent carcinomas of the pancreas are more sinister causes...in these cases, inflammatory fibrosis or malignant infiltration narrows the pyloric channel, producing pyloric outlet obstruction...

 in rare instances, hypertophic pyloric stenosis is the result of prologned pyloric spasm or delayed appearance of the childhood pattern...

 duodenal atresia...double bubble...happens right after birth...mom has polyhydraminos...

 Autoimmune Gastritis

Type A Gastritis (Fundal)

this form of gastritis accounts for less than 10% of cases of chronic gastritis...it results from the presence of autoantiboides to the gastric gland parietal cells and intrinsic factor, including one against the acid producing enzyme, H+, K+ ATPase...

gland destruction and mucosal atrophy lead to loss of acid production...

in the most severe cases, production of intrinsic factor is lost, leading to pernicious anemia...this uncommon form of gastritis is seen in association with other autoimmune disorders, such as hashimoto thyroiditis and addison disease....

 autoimmune gastritis is characterized by diffuse mucosal damage of the body fundic mucosa, with less intense to absent antral damage...gastritis in the setting of environmental causes (including infection by H. pylori) tends to affect antral mucosa or both antral and body fundic mucosa...

 by visual inspection, the mucosa is usually reddened and has a coarser texture than normal...the inflammatory infiltrate may create a boggy appearing mucosa with thickened rugal folds, mimicking early infiltrative lesions...

 alternatively, with long standing atrophic disease, the mucosa may become thinned and flattened...regardless of cause or location, the histologic changes are similar...an inflammatory infiltrate of lymphocytes and plasma cells is present within the lamina propria...

 chronic gastritis usually causes few symptoms...nausea, vomiting, and upper abdominal discomfort may occur...individuals with advanced gastritis from H. pylori or other environmental causes are often hypochlorhydric, owing to parietal cell damage and atrophy of body fundic mucosa...

 b/c parietal cells are never completely destroyed, however, these patients do not develop achlorhydria or pernicious anemia...serum gastrin levels are usually witin the normal range or only modestly elevated...

 when severe parietal cell loss occurs in the setting of autoimmune gastritis, hyochlorhydria or achlorhydria and hypergastrinemia are characteristically present...circulating autoantibodies to a diverse array of parietal cell antigens may be detected...a small subset of these patients (10%) may develop overt pernicious anemia after a period of years...

Peptic Ulcers

peptic ulcers are chronic, most often solitary, lesions that occur in any portion of the GI tract exposed to the aggressive action of acid peptic juices...peptic ulcers are usually solitary lesions less than 4cm in diameter, located in the following sites, in order of decreasing frequencey:

 duodenum, first portion...

 stomach, usually antrum 85-90%...

 the apparent role of H. pylori in peptic ulceration connot be overemphasized...H. pylori infection is present in virtually all patients with duodenal ulcers and about 70% of those with gastric ulcers...furthermore, antibiotic treatment of H. pylori infection promotes healing of ulcers and tends to prevent their recurrence...hence, much interest is focused on the possible mechanisms by which this tiny spiral organism tips the balance of mucosal defenses...

 H. pylori secretes a urease, which generates free ammonia, and a protease, which breaks down glycoproteins in the gastric mucus...the organisms also elaborate phospholipases, which damage surface epithelial cells and may release bioactive leukotrienes and eicosanoids...

 neutrophils attracted by H. pylori release myeloperoxidase, which produces hypochlorous acid, yielding, in turn, monochloramine in the presence of ammonia...both hypochlorous acid and monochloramine can destroy mammalian cells...

 Menetrier Disease

middle aged men...

 Gross: enlarged rugal folds in the body and fundus...

 Micro: massive foveolar hyperplasia with replacement of the parietal and chief cells...

 decreased acid production...

 protein losing enteropathy...

 increased risk of gastric cancer...

 Gastric Carcinomas

among the malignant tumors that occur in the stomach, carcinoma is overwhemingly the most important and the most common (90-95%)...

 gastric carcinomas involve the antropyloric region in 50-60% of cases...

 next in order of frequency are lymphomas (4%), carcinoids (3%), and malignant stromal cell tumors (2%)....

 Intestinal Gatric Carcinoma

decreasing in frequncy in the US and is thought to arise from gastric mucous cells that have undergone intestinal metaplasia...consists of infiltrating groups of malignant type glands that are similar to colon adenocarcinomas...

 Diffuse Type Carcinoma

not decreasing in frequency in US and is thought to arise from native gastric mucous cells...the diffuse type of gastric adenocarcinoma consists of infiltrating individual mucin-secreting malignant cells (signet ring cells) that do not form glandular structures...

 the presence of carcinogens, such as N-nitroso compounds and benzopyrene, appears to be particularly important...thus, lack of refrigeration; consumption of preserved, smoked, cured, and salted foods; water contamination with nitrates; and lack of fresh fruit and vegetables are common themes in high risk areas...

 host factors are the second major area of scrutiny...infection by H. pylori leading to chronic gastritis and intestinal metaplasia is thought to be a contributing, but not sufficient, factor for gastric carcinogenesis...

 Kruckenberg's Tumor - metastatic tumor of stomach spread to ovary...

 Virchow's Tumor - metastatic tumor of stomach spread to left supraclavicular node...

 Sister Mary Joseph - metastatic tumor of stomach spread to umbilicus...

 gastric carcinoma is an insidious disease that is generally asymptomatic until late in its course...the symptoms include weight loss; abdominal pain; anorexia; vomiting; altered bowel habits; and, less frequently, dysphagia, anemic symptoms, and hemorrhage...

 the 5-year survival rate of surgically treated early gastric cancer is 90-95%, with only a small negative increment if lymph node metastases are present...in contrast, the 5 year survival rate for advanced gastric cancer remains below 15%...

 signet ring cell pattern (linitis plastica)...