Module 2: GI: Colon Cancer, Appendicitis, Hepatitis and Cirrhosis Flashcards
To finish off cancer and polyps of the colon. I will discuss Colon Adenocarcinoma. Describe the gross and histological images in slide 20
Tumors in proximal colon: grow as polyploidy, exophytic masses (cauliflower appearance)
Tumors in distal colon: tend to be annular lesions that produce napkin ring constriction and luminal narrowing
–both grow into the bowel wall over time and become palpable firm masses
Barium Enema Xray: apple core lesion in the sigmoid colon
Histopathology: malignant glands invading the submucosa and muscularis propia (sequential process) –can invade the serosa next – lymph nodes
–note carcinoma once broken through the submucosa
What are the predisposing factors for colon adenocarcinoma?
Mostly sporadic and in patients over 50
Pre-disposing factors: FAP (Genetic), HNPCC (genetic), high fat diet, low fiber, diet rich in refined carbs, low in vitamins A,C, and E, ulcerative colitis and Crohn’s
What is the pathogenesis for colon adenocarcinoma?
Two molecular pathways:
1.APC/B-catenin pathway (chromosomal instability pathway) (85%-90%) of cases::
—normal colon, then loss of APC gene (born with one hit this is the additional hit) —> decreased intercellular adhesion and increased proliferation
–colon at risk, KRAS mutation → unregulated intracellular signal transduction
—Adenoma, loss of tumor suppressor genes —> increased tumorigenesis
–Carcinoma
2. Microinstability Pathway (10-15%) of cases:
–may arise from adenomas or other lesions
–defect in DNA mismatch repair genes (MLH1, MSH2, MSH6 and PMS)
–85% are sporadic and 15% familial (HNPCC/lynch syndrome)
Signet ring cells = E-cadherin mutation
What are the common sites for adenocarcinoma?
Recto sigmoid, ascending, descending
What are the signs and symptoms for adenocarcinoma?
Ascending Colon (Right sided): occult bleeding leading to iron deficiency anemia (Esp in males over 50 and postmenopausal women) ---> fatigue Descending Colon (Left sided): bright red blood, mucus and napkin ring constriction on gross → more likely to cause intestinal obstruction → pencil shaped stools --Usually solitary
What investigations can be done for adenocarcinoma?
Screen patients over 50 with colonoscopy
If suspect colon cancer:
Barium enema study before taking a biopsy
CEA tumor marker: good for monitoring recurrence not useful for screening
What is he course/complications for adenocarcinoma?
Metastasis to the regional lymph nodes and then to the liver (liver drains the GI) then the lungs
If metastasis than survival rate is 4%
TNM staging determines the prognosis
Finally the last thing to discuss in the GIT will be appendicitis. What is the etiology?
Fecal obstruction of the lumen of the appendix (most common)
What is the pathogenesis for acute appendicitis?
Obstruction — continued secretion of mucinous fluid — increased intraluminal pressure — collapse of draining veins —- ischemic injury —- bacterial proliferation — inflammation and edema
What are the symptoms for appendicitis?
Periumbilical Pain that then moves to the RLQ (McBurney’s Point), nausea, vomiting and rebound tenderness
- –periumbilical pain first due to visceral peritoneum
- -RLQ pain, they can now localize the pain
What does the biopsy look like for appendicitis?
Presence of neutrophils all the way to the muscularis propria
–therefore a pathologist can tell its appendicitis because inflammation all the way down to the muscularis propria
What do you see on CBC in a patient with appendicitis?
Increased neutrophils (Due to the inflammation) Bands cells (leukomoid reaction and left shift)
On physical examination what signs is the patient positive for?
Rovsing
Psoas
Obturator Sign
What are complications of appendicitis?
Perforation Peritonitis Peri-Appendiceal Abscess Liver abscess Bacteremia
Now moving onto liver pathology. The first major thing to discuss is the various hepatitis’s. Give the features of Hep A.
Caused by a single stranded RNA virus Fecal-oral route No chronicity No carrier state Increased incidence in travelers Common in children Check IgM levels for recent infection
Give the features of Hep B
Hep B (serum hepatitis):
Cause by enveloped DNA virus with a long incubation period (4-26 weeks)
Transmission: transfusion of blood, sexual intercourse, IV drug abuse, homosexuals, needle stick injuries
High risk of malignant transformation and increased incidence in developing countries
Histology: Ballooning degeneration and ground glass appearance of hepatocytes
Carrier state
Give features of Hep C
Most important cause of transfusion associated hepatitis and chronic liver disease
Parenteral route; chronic and persistent
Inherently unstable virus so no vaccine yet
Histology: extensive macrovasicular and microvesicular steatosis; damage to the portal tracts and alot of apoptotic bodies
Give features of Hep D.
Parenteral Route
Co infection and superinfection with hepatotropic virus
Super infection is more dangerous
Co-infection with Hep B
Super infection so Hep D superimposed on present Hep B
Give features of Hep E.
Hep E:
fecal oral route
No chronicity (unless immunosuppressed post liver transplant patient)
High mortality in prego females
Severe cholestasis which persists for longer periods