Chapter.10- The G.I System Flashcards
What are the most common type of non-neoplastic polyp?
Hyperplastic polyps
What are hyperplastic polyps?
Benign lesions most often found in rectosigmoid region
What are hamartomas?
Developmental abnormalities in which the normal components of the tissue aggregate in an abnormal manner. These involve Peutz-Jeghers polyps and Juvinile polyps
Classification of Intestinal Tumors
- ) Non-neoplastic polyps: hyperplastic polyp, inflammatory polyp, juvinile polyp, Peutz-Jeghers polyp, lymphoid polyp
- ) Benign neoplasms: tubular adenoma, villious adenoma, benign stromal tumors
- )Malignant neoplasms: adenocarcinoma, carcinoid lymphoma, sarcoma
What are inflammatory polyps?
Known as pseudopolyps. Represent multiple fragments or regenerating mucosa surrounded by broad ulcers
What do neoplastic polyps consist of?
Neoplastic epithelium that show no evidence of differentiation
What are neoplastic polyps classified as?
Tubular, villous, and tubulovilous adenomas
All are considered pre-malignant because they can progress to adenocarcinoma
What are tubular adenomas?
Most common, account for 75% of neoplastic polyps.
Typically attached to the stoma by a stalk
What are villious adenomas?
Sessile, broad based tumors, composed of epithelial cells alligned into elongated villi. They project into the lumen of the intestine. forming finger like protrusions. Invasive carcinoma is found in alomst 50% of these tumors.
Peak incidence (age) for colorectal cancer
Between 50-70 years of age
Adenocarcinoma accounts for % of intestinal cancers
95%
Incidence of colorectal cancer
- 10x more common in USA and Western countries than in Asia
- Most cases occur spontaneously with no identifyable risk factor
- 20% genetic
Where are adenocarcinomas found in the intestine?
-May develop in any part, but most commonly found in the left part of the intestinal loops
- 45% in recto-sigmoid area
- 25% in cecum an ascending colon
- 30% in remaining part of the colon
Most adenocarcinomas originate as
neoplastic polyps
Tumors from the right colon tend to grow as…
fungating masses, or ulcerated, shallow cratorlike lesions
How do adenocarcinomas of the sigmoid or rectum present?
They infiltrate the intestine circumferentially, producing “napkin ring” circumferential narrowing
What is the 5 year survival rate for stage 4 colorecta cancer?
Less than 10%
Early symptoms of adenocarcinoma
May produce no symptoms at all, may be diagnosed by screening (endoscopy, biopsy, or occult blood)
Clinical symptoms of left sided adenocarcinoma of the colon
Left sided lesions, especially the rectum, tend to narrow the passage of stool=constipation, thin pencil like stools
Hematochezia may occur, but in advanced lesions
Symptoms of adenocarcinoma of the right colon and cecum
Tend to be silent or non specific (weakness or fatigue)
Chronic blood loss may cause anemia
What tumor marker is used in the monitoring of patients with colorectal cancer?
CEA (Carcino-embryonic antigen)
Not useful in diagnosis since it can be released by non-specific intestinal inflammations, but
What are carcinoids?
term used for neuroendocrine tumors of low malignancy
Where are carcinoids located in the GI tract?
Can occur in all intra-abdominal parts of the GI tract
Most common in the small intestine
located in the sub-mucosa where they form nodules, elevating the lower mucosa
Genetic factors in colon cancer etiology
-Can account for 20%
Where do carcinoids of the GI tract tend to metastisize?
Tumors larger than 2cm tend to matastaize the lymph nodes and liver
What is carcinoid syndrome?
Carcinoids that have metastesized to the liver release their secretory products into the blood.
- release seratonin, bradykinin, histamine
- therefore bronchial wheezing, diarrhea
Long lasting carcinoid syndrome results in
fibrosis of right ventricle and tricuspid valve
Components of upper GI tract
Mouth, Pharynx, esophagus, stomach, and dudenum
In the uppder GI tract the epithelium of the mucosa is
Squamous
Components of lower GI tract
small and large intestine, appendix, rectum, anus
In the lower GI tract (stomach to anus) the epithelium of the mucosa is
Cuboidal gladular epithelium
In the lower part of the anus, the epithelium is
Squamous
Describe the musuclar component of the GI tract, in terms of structure
Above the diaphragm the muslce is covered by adventitia, and below the diaphragm the muscle is covered peritoneum.
This is important because the upper parts (such as esophagus) does not have a mesothelial lining, therefore it is much easier for cancer to spread into the wall of the esophagus and spread into adjacent tissues
Blood supply of the GI system
- supplied by the mesenteric arteries
- Recives 1/6 of cardiac output, but this depends on the needs are the GI tract (ex. digestion vs. rest)
- Portal system drains the venous blood fro the intestines
What are the 4 layers of the GI tract?
muscosa, submucosa, muscularis, serosa
Lymphatic Supply of the GI system
Intestines habe a rich supply of lymphatics
Begins at lacteals at mucosal wall, and drains to lynph nodes and lymphatic channels that drain into the throacic duct
These lymphatics play a role in absorbing nutritients, and in the immune response
Significant route for the spread of cancer
Innervation of the GI Tract
-Mostly derived from the autonomic nervous system
Main functions of the GI Tract
Ingestion
Mastication (chewing)
Deglutition (swallowing)
Digestion: beings in mouth with saliva
Absorption
Excretion
Main exocine and endoctine functions of the GI tract
(table: organ, secretory product, function)
Diseases of the oral cavity
Developmental abnormalities
Inflamation
Dental Carries
Periodontal disease (bacterial infection the gums and tissues around the mouth)
Stomatitis (inflammation of roal mucosa)
Oral Cancer
Most common developmental abnormality of the oral cavity
Cleft lip: lack of fusion from the fetal nasal and maxilliary processes that form the upper lip
May be associated with cleft palate
Cleft lip more common in males
What are dental carries?
- Most common in children and adolescents
- Begins as a bacterial plaque which then leads to a defect in the enamel
- Deeper defects allow bacteria to enter the pulp cavity (pulpitis), where people experience pain
- Influenced by lifestyle and diet (high sugar)
- Saliva and fluoride are protective
What is stomatitis?
- Inflammatio of the mouth
- Can ocurr in the setting of systemic disease
Ex. Herpes infection (vesicles), and candida (immunompromised, bronchodilators/steroids)
Ex. Aphthous stomatits (canker sores): Uknown etiology, health spontanously
Oral Cancer
Can occur anywhere in the oral cavity
Most are squamous cell carcinoma
Risk factors: Tobacco (smoking and chewing), chronic alcoholism
Males > females: 10:1 Lip, 2:1 oral cavity
Mean age of dx.: 55-60yo
Oral cancer is morphologically present as
Leukoplakia: white elevated plaque that covers the mucosal surgafe
Erythroplakia: Red plaque that appears distinct
Ulcer: disruption of mucosa
crater: deeper depression
Nodule
Salivary gland disease
Inflammation of the salivary glands: sialadenitis
Iinfectious:
- Suppurative: stapyloccocus A or Streptococcus B,
- Viral: mumps virus common in children
Autoimmune:
- Sjogrens disease: Presents as systemic, but affets the salivary and lacrimal. Enlargement of gland is attributed to infiltrates of plasma cells and lympthocytes. Increased risk of lymphoma.
Clinically can present as swelling of glands or xerostomia
Salivary gland neoplasms
Can affect major or minor salivary glands
More than 60% are benign
Frequently occur if not removed completely
Most Common tumor is pleomorphic adenoma (70%)
Diseases of the esophagus: Clinical Presentation
- Dysphagea
- Esophageal (retrosternal pain)
- Aspiration or regurgitation
Esophageal Atresia
Developmental
lack of lumen with or without esophageal fistula
babies will vomit ingested milk
without repair, babies will die of starvation or aspiration pneumonia
Hiatal hernia
most common cause of reflux
Alterns function of lower esophageal sphincter and facilitates reflux of gastric juice into the esophagus
Sliding vs. paraesophageal
Displacement of gastric cardia from abdominal cavity into the thoracic cavity through diphragmatic hiatus
tone of LES decreased by smoking, caffeine, pregnancy
Achalasia
Spasm of LES and dilation proximal to the site of spasm
Results in dysphagia
Most cases idiopathic, but can be secondary to chagas, cancer, amyloidosis, scleroderma
Esophagitis
- Reflux of gastric juice (peptic esophagitis) with pepsin and HCL-leadinging to ulcerations; defects repaired by metastatic epithelium (Barretts esophagus)
Can be caused by infections: Viruses (herpes, cytomegalo virus), fungi, or bacterial superinfection
Can be caused by chemical irritants: (lye)
Esophageal varicies
- Typically caused by cirrhosis of the liver, marked by portal HTN
- May cause hematemesis
- most common cause of GI bleeds, high mortality rate
Mallory-Weiss: laceration of small blood vessels @ gastro-esophageal junction during strenuous vomiting. More common is alcoholics. Marked by hematoemesis
Carcinoma of the esophagus
(incidence, risk factors, prognosis, clinical presentations)
Accounts for 4% of all cancers
higher incidence in Asian and Africa (carcinogen in soil or food?)
Correlates with alcohol, tobacco abuse
more common in men
3x more common in blacks than whites
poor prognisis: average survival <2years, 5year<25%
Clinical: present with pain, bleeding, malodorous breath
Carcinoma of the esophagus
Locally invasive, at dx. most have spread to adjacent organs
Upper and lower: Swquamous cell carcinoma
Lower Esophagus: Adenocarcinoma (developig in Barretts)
Most carcinomas originate from lower esophagus
Diseases of the Stomach: Symptoms
Pain: Midline, upper abdomen, due to ulceration of mucosa and HCL
Vomitting: obstruction of pylorus
Bleeding: acute with hematoemesis or chronic with melena
Dyspepsia: nausea, lack of appetitie, food aversion
Systemic consequences: iron deficiency anemia caused by chronic blood loss, vitamin B12 malabsorption
Congenital abnormality of stomach
-Most common: Pyloric stenosis, occurs in pre-natal period
boys more affected
projectile vomiting.
Gasrtitis
Acute (erosive): stress, shock, food, exogenous chemicals
- Erosions
- Ulcerations
Chronic:Atropic gastritis with or without intestinal metaplasia
- etiology unknown
- H.Pylori
- Autoimmune (with pernicious anemia)- impaired absorption of B12
Increased risk for gastric cancer
Peptic Ulcer disease
- Multifactorial
- Mucusal ulceration that extends to the gastric epithelium into muscularis
Contributing factors include:
- Gastric juice: HCL, pepsin
- Mucusal barrier defects: stress, shock, NSAIDS, smoking reduces resistance
- H.Pylori
Clincial Features of Pepic Ulcers
Mostly distal stomach and proximal duodenum
Duodenal 4x more common than gastric
Gastric >40, Duodenal any agea
Presentation: 1-3hours after a meal or at night
Mid-epigastric
Nausea, vomiting, weight loss, melena, iron-deficiency
Peptic Ulcers: appearance
-punched out, round defects
bottom of the ulcer consists of glandular amorphous material, HCL keeps clean
margins of the ulcer are sharp
Complications of peptic ulcer disease
Hemmorrhage (most common): hematemesis, melena, iron deficient anemia
Penetration into the pancreas: acute pancreatitis
Perforation: Peritonitis (duodenal ulcers may extend to the intestinal wall and form a hole, leaking contents into the peritoneum)
Cicatrization: stenosis (may be caused by scarring)
Gastric Neoplasms
Benign epithelial tumors: polyps (hyperplastic, tubular, vilious)
Benign Stromal Tumors (ex.leiomyoma)
Malignant Tumors
- Adenocarcinoma (most common, 90%)
- lymphoma (stomach most common site of GI lymphomas)
Carcinoma of the stomach incidence and etiology
90% of gastric malignancies
8x more common in Japan and Chile (diet, soil)
Incidence has decreased last 70 years in USA
Etiology is unknown, suspect H.Pylori, and nitrosamines in food
Macroscopic features of gastric carcinoma
Forms: 75% in distal part of the stomach
- Superficial: flat, resembling early stages
- Polypoid: protrude into lumen of the stomach
- Ulcerated: resemble peptic ulcers, but increased irregulartity
- Diffuse infiltrating: permeate gastric wall and “linitis plastica” leather like bottle
Histology of gastric carcinoma
- Adenocarcinoma
- Metastasize to regional lymph nodes, to liver and lungs
- Virchows node: left supraclavicular lymph node
- Krunkenburgs tumor: bilateral ovarian involvement
Clinical Features of Gastric Carcinoma
(Symptoms, prognosis)
Symptoms: non-specific, weight loss, anemia, weakness, vomiting, loss of appetite, dysphagia, bleeding
- ditant metastases
- most tumors are at advanced stage at dx.
Poor prognosis 5year<25%
Gastrointestinal Lymphoma
May be secondary (from lymph nodes or bone marrow)
Primary GI lymphoma
- Originate in mucosa-associated lymphoid tissue
- localized masses
- most MALTomas related to h.Pylori
**stomach most common site of GI lymphomas**
Hirschsprung’s Disease
Abnormality of inervatio in the rectum and sigmoid colon
Intramural ganglion cells do not develop -
- segment lacking inervation is in spasm
- segment proxmial dilates and causes megacolon.
Diseases of the Intestines
Developmental: Hirschsprungs, congenital diverticula (Meckels)
Diverticulosis, hernias, obstructions
Vascular Disorders
Inflammatory bowel
Infections: peritonitis
Malabsorption
Neoplasm
Congenital Diverticula
Best known: Meckels
- incompletely obliterated omphalomesenteric duct (small intesting to umbilical)
- meckels diverticulitis is similar to acute appendicitis, except LLQ pain instead of RLQ pain
Diverticulosis of the Colon
Can be solitary or multiple
Any part of the GI tract
Sigmoid most clinically significant
Older persons with chronic constipation
weakneing of intestinal wall at any point of arterial entry through muscle
Hemmorrhoids: what are they and what causes them?
Angiodysplasia: What is it, what does it cause?
Localized vacular lesion of the colon
may cause unexplained bleeding-dilated thin walled blood vessels
Mesenteric Thrombosis
Common complication of atherosclerosis
most important cause of transmural infarction
typically affects small intestines
Inflammatory Bowel Disease: Incidence
Ulcerative Colitis: incidence 70-100 per 100,000 persons per year in USA
Crohns: incidence 20-40 per 100,000, per persons per year
Cause unknown, may be stress or genetics
more common in whites
Crohns VS. Ulcerative Colitis: Comparison Chart
Crohns Disease: What is it, what % of colon is involved, what does it lead to
-Chronic inflammation of the Gi tract: terminal ileum and colon
50% both ilium and colon, 30% just ilium, 20% just colon
- 1/3 have extraintestinal involvement
- Terminal ilium aphtous ulcers, typically overlie lymphoid aggregates
- inflammation extends through the wall of the mucosa,
- Chronic inflammation is associated with fibrosis-cobblestone mucusa
- Fibrotic intestine may be narrowed
- inflammation of serosa leads to adhesions with adjacent intestinal loops which may lead to fistulas
- 50% associated with granuloma
Clinical Presentation of Crohns disease
Presentation varies- common is diarrhea, abd. pain, weight loss
Later stages:
- constipation because of narrowing
- malabsorption- weight loss, vitamin deficiency
1/3 extraintestinal symptoms: arthritis, skin lesions, liver disease, eye lesions
Ulcerative Colitis: what is it? where in the intestine is it most commonly seen?
- intestinal inflammation of unknown etiology
- most often involves large intestine
- From initial rectal lesions, inflammation spreads proximal, involving the entire colon
- does not involve ileum, involves the appendix in 30%
Ulcerative Colitis: Patho
Limited to colonic mucusa.
Starts as edematous patch - sandpapered
As disease progresses mucosal lesions become more prominent.
Crypts and aggregates of leukocytes in lesions (crypt abscess)
ulcerations bleed easily and become infected
Colonic ulcerations spread leaving behind small remnants of mucosa - inflammatory pseudopolyps- some polyps are foci of regeneration, some may undergo malignant transformation
Ulcerative Colitis: Clinical Manifestations
Mild symptoms to evolve in chronic diarrhea, rectal pain, bleeding
70% chronic, 20% resistive to tx., 10% single episode
Gastrointestinal Infections:
Caused by
- a disturbed balance of colonic flora: pseudomembranous colitis from overgrowth c.diff as a result of abx.
- Introduction of pathogens: food poisoning, bacteral toxins,
Infectious diarrhea in small intestine: ecoli, vibrio cholerae, giardia, rotovirus
Infectious diarhhea in large intestine: ecoli, norwalk, shigella
Comparison of Diarrhea between small and large intestine
Stool characteristic table: volume, appearance, blood, leukocytes, proctoscopy
Causes of Diarrhea
a. ) ingested toxin
b. )toxins formed by bacteria colonising the intestine
c. ) bacteria that invade the wall of the intestine
Pseudomembranous Colitis:
What is the cause?
Acute Appendicitis: Caused by
- one of the most common acute intestinal infection
- caused by enterogenic bacteria of normal intestinal flora that becomes pathologic after obstruction of the lumen of the appedix (feces, lymphnode, intramural tissue, worm).
Acute appendicitis Clinical features
Sudden pain, fever leukocytosis
Pain strongest in RLQ (McBurneys Point), may be referred to umbilican area-peritonitis
tenderness/Rebound pain
Appendectomy is only tx.
Acute peritonitis:
Defined as, types
Inflammation of the peritoneal lining
local or diffuse
sterile or infectious
Acute Sterile Peritonitis caused by
- Acute pancreatitis with spill of enzymes
- Rupture of gallbladder with bile entry to peritoneum
Acute infectious peritonitis caused by
- rupture of stomach (PUD) or intestines (appy)
- Spread of infection from fallopian tubes
- rupture of abscess
- Infection of pre-existing ascites
Clinical Features of Acute Peritonitis
- sharp abdominal pain
- rebound tenderness
- voluntary guarding
- intestinal peristalsis slows down-intestinal paralysis
- treatment- surgical exploratio to remove puss and repair rupture site
- All forms high mortality
Causes of intestinal obstruction
Intestinal Obstruction: Hernia
Defined as, types, most common, and if left untreated
*see slide
Inguinal is most common
If left untreated- leads to adhesions and subsequent incarceration. The neck of the hernia may compromise blood flow causing strangulation and gangrene of intestinal loop.
Intestinal Obstruction: Intussusception
Definted as, causes in children and adults, complication
-bloodflow of invaginated segment may become compromised b/c constriction of outside segment, and could lead to necrosis
Volvulus: Defined as, involves, can lead to
Pathogenesis of Malabsorption
*usually caused by more than 1 mechanism
Malabsorption is characterized by
Deficency of nutrients- most prominent are protein and lipids
- Protein deficiency leads to anemia, decreased iron, hypoalbumin -edema
- Decreased fat absorption: fatty stools (steatorrhea), decreased absorption of fat soluble vitamins. low k =bleeding disorders, low vitD= osteomalacia, hypocalcemia
Malabsorption: Intraluminal digestion may be impaired by
*deficiency of gastric juices* - these patients do not absorb b12 and can present with anemia
*deficiency with bile- impaired fat absorption
Celiac Sprue:
Whipple’s disease
