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44 Cards in this Set

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Congenital disorders of the small intestine
duplication
malrotation
omphalocele
gastroschisis
omphalocele
abominal musculature fails to form -- birth of an infant with hernitaion of abdominal contents into a ventral membranous sac.
gastroschisis
a portion of the abdominal wall fails to form altogether, causing extrusion of the intestines.
Atresia
a COMPLETE occlusion of the intesitinal lumen.

stenosis: narrows, but doesn't occlude the lumen.
Meckel diverticulum
is a congenital sacculation on the antimesenteric border of the ileum caused by persistence of the VITELLINE DUCT.

TRUE diverticulum: possesses all the coats of the normal intestine = mucosa, submucosa, muscularis propria.
meconium ileus
earliest manifestation of cystic fibrosis = accumulation of tenacious meconium in the small intestine.
Bacterial diarrhea
the most significant factor in infectious diarrhea is increased intestinal secretion stimulaed by bacterial toxins and enteric hormones.
toxigenic diarrhea
refers to frequent, watery stools caused by infection with toxin-producing bacteria.

prototypic organisms: vibrio cholerae, and toxigenic strains of E. Coli

aka travelers' diarrhea (e.coli is most common pathogen)
Toxigenic diarrhea characterized by 3 things:
 Damage to the intestinal mucosa is minimal or absent.
 The organism remains on the mucosal surface, where it secretes its toxin.
 Fluid secreted into the small intestine causes watery diarrhea, which can lead to dehydration, particularly in the case of cholera.
Diarrhea caused by invasive bacteria
cause diarrhea by directly injuring the intestinal mucosa.

Shigella, salmonella, certain strains of E.coli

tend to infect the DISTAL ILEUM AND COLON.

Ulceration and hemorrhage may accompany diarrhea.
Hirschsprung disease = congenital megacolon
• An uncommon familiar disorder in which colonic dilatation results from defective innervation of the rectum.
• The lesion is a congenital absence of ganglion cells in the wall of the rectum.
• Rectum reveals a constricted and spastic segment that corresponds to the aganglionic zone. Bowel is dilated proximal to this zone.
Secretory diarrhea
Net intestinal fluid secretion leads to the output of more than 500 mL of fluid stool per day, which is isotonic with plasma and persists during fasting.
Osmotic diarrhea
Excessive osmotic forces exerted by luminal solutes lead to output of more than 500 mL of stool per day, which abates upon fasting. Stool exhibits an osmotic gap (stool osmolality exceeds plasma electrolyte concentration by ≥50 mOsm).
exudative diseases
Mucosal destruction leads to output of purulent, bloody stools that persist on fasting; stools are frequent but may be small or large volume.
deranged motility
Improper gut neuromuscular function may produce highly variable patterns of increased stool volume; other forms of diarrhea must be excluded.
Describe malabsorption syndromes.
Malabsorption is characterized by defective absorption of fats, fat-soluble and other vitamins, proteins, carbohydrates, electrolytes and minerals, and water.
The most common clinical presentation is chronic diarrhea, and the hallmark of malabsorption is steatorrhea (excessive fecal fat content).
Celiac disease
Celiac disease (also referred to as celiac sprue, gluten-sensitive enteropathy) is a chronic disease, in which there is a characteristic mucosal lesion of the small intestine and impaired nutrient absorption, which improves on withdrawal of wheat gliadins and related grain proteins from the diet.
celiac disease is characterized by what 3 things?
o Generalized malabsorption
o A typical, but nonspecific, small intestinal mucosal lesion
o A prompt clinical, but slower histologic, response to the withdrawal of gluten-containing foods from the diet.
Hallmark of celiac disease
• Hallmark: flat, small, intestinal mucosa with:
o Blunting or total disappearance of cilli
o Damaged epithelial cells on the mucosal surface
o Increased cellularity of the lamina propria but not of the deeper layers.
Lactase Deficiency
• Lactose is one of the most common disaccharides in the diet.
• Widespread disorder of carbohydrate absorption.
• Affects 2/3 of Asian and African adults
• Symptoms begin during adolescence.
• Patients complain of abdominal distention, flatulence (gas), diarrhea after ingestion of dairy products. Symptoms relieved by eliminated milk from the diet.
appendicitis
Inflammatory disease of vermiform appendix that may result in transmural necrosis and perforation.
complications of appendicitis
Periappendiceal abscesses; fistulous tracts; pylephebitis, abscesses, diffuse peritonitis and septicemia, wound infection
carcinoid tumor
arise from cells of the neuroendocrine system of the gut.

most commonly secreted hormone: serotonin

Malignant potential related to size > 1cm malignancy is at risk.
clinical features of carcinoid syndrome
Vasomotor distubances
Cutaneous flushes and apparent cyanosis (most patients)
Intestinal hypermotility
Diarrhea,Cramps, nausea, vomiting (most patients)
Asthmatic bronchoconstrictive attacksCouth, wheezing, dyspnea (about one third of patients)
Hepatomegaly
Nodular liver owing to hepatic metastases (some patients)
Systemic fibrosis (some patients)
Cardiac involvement
Pulmonic and tricuspid valve thickening and stenosis
Endocardial fibrosis, principally in the right ventricle (Bronchial carcinoids affect the left side)
Retroperitoneal and pelvic fibrosis
Collagenous pleural and intimal aortic plaques
mediterranean lymphoma
1) poor countries;
2) young men;
3) proliferative disorder of intestinal B cells that secrete IgA;
4)Leads plasma cell infiltrates that produce mucosal atrophy and malabsorption.
western type lymphoma
1) Older adults and children;
2) fungating mass that projects into the ileum;
3) plaque-like nodules;
4) diffuse thickening or elevated ulcerated lesions;
5)occult bleeding is common;
6) Microscopically all varieties of lymphoma;
7) 5-year survival rate is <10%.
adenocarcinoma (SI)
Located in duodenum and jejunum. Risk for Chron’s patient is ~100%, Occult bleeding is prominent may lead to iron deficiency anemia. 5-year survival <20%.
primary lymphoma (SI)
15% of bowel cancers. Risk is increased in patients with immunodeficiency or those treated with immunosuppressive drugs.
colorectal carcinogenesis
see slides
Inherited Adenomatous Polyposis Syndromes
Gardner Syndrome:
o An autosomal dominant, familial disorder characterized by
1. Gastrointestinal polyposis, principally in the colon but commonly in the stomach and the vicinity of the ampulla of Vater
2. Osteomas of the skull, mandible, and long bones
3. Soft-tissue tumors of the skin
o Garner syndrome ultimately progresses to cancer of the colon.
Peutz-Jeghers Syndrome
An autosomal dominant, hereditary disorder characterized by intestinal polyps and mucocutaneous melanin pigmentation, which is particularly evident on the face, buccal mucosa, hands, feet, and perianal region, as well as genital areas.

Polyps are NOT true neoplasms but are hamartomas.

2-3% of patients develop adenocarcinoma.
Familial Adenomatous Polyposis
FAP is the archetype of the adenomatous polyposis syndromes. It is caused by mutations of the adenomatous polyposis coli (APC) gene on chromosome 5q21.

Classified as classic FAP, attenuated FAP, Gardner syndrome, and Turcot syndrome.
Adenomatous polyps are segregated into three subtypes on the basis of the epithelial architecture:
Tubular adenomas: tubular glands
Villous adenomas: villous projections
Tubulovillous adenoma: a mixture of the above.
intussusception
• A form of intraluminal small bowel obstruction in which a segment of bowel (intussusceptum) protrudes distally into a surrounding outer portion (intrussuscipiens), much in the same way that a segment of a telescope inserts into the adjacent one.
• Usually a disorder of infants/children = unknown cause.
• Adults – leading cause is commonly a lesion in the bowel wall, such as a Meckel diverticulum or polypoid tumor.
• Peristalsis drives the intussusceptum forward.
volvulus
• A cause of an acute abdomen and an example of an intestinal obstruction in which a segment of gut twists on its mesentery, thereby kinking the bowel and usually interrupting the blood supply.
adhesions
• Fibrous scars from previous surgery or peritonitis may cause obstruction by bending/angulating the bowel or by directly compressing the lumen.
hernias
incarceration of a loop of bowel in an inguinal or femoral hernia.
predisposing conditions for ischemia
arterial thrombosis
arterial embolism
venous thrombosis
non-occlusive ischemia
Miscellaneous: radiation injury, volvulus, stricture, amyloidosis, diabetes mellitus, and internal or external herniation.
diverticular disease
see slides
Non-neoplastic (Benign) Polyps
Hyperplastic polyps
Hamartomatous polyps
Juvenile polyps
Peutz-Jeghers polyps
Inflammatory polyps
Lymphoid polyps
Neoplastic Epithelial Lesions
Benign 
Adenoma*
Malignant: 
Adenocarcinoma*
Carcinoid tumor
Anal zone carcinoma
Mesenchymal Lesions
Gastrointestinal stromal tumor (GIST)
-Neuroma
-Lipoma
-Angioma
-Kaposi sarcoma
The malignant risk with an adenomatous polyp
Correlated with three interdependent features:
polyp size,
histologic architecture,
severity of epithelial dysplasia.
Cancer is rare in tubular adenomas smaller than 1 cm in diameter.
The risk of cancer is high (approaching 40%) in sessile villous adenomas more than 4 cm in diameter.
Severe dysplasia, when present, is often found in villous areas.
consequences of malabsorption
see slide