Familial adenomatous polyposis involves mutation of the ____ gene on chromosome ____.
You are going to perform a colonoscopy on a patient with familial adenomatous polyposis. What do you expect to find?
Pancolonic involvement, including the rectum
A patient is found to have thousands of polyps on colonoscopy; he has a history of bone and soft-tissue tumors. What syndrome do you suspect?
Turcot syndrome describes the combination of FAP and what other finding?
Glioma and medulloblastoma (remember: TURcot = TURban)
Hereditary nonpolyposis colon cancer, or Lynch syndrome, involves mutations of DNA ____ ____ genes.
True or False? Hereditary nonpolyposis colon cancer rarely involves the proximal colon.
False; the proximal colon is always involved
A patient presents with fever, low blood pressure, and new murmur. Blood cultures grow Streptococcus bovis and he is started on appropriate antibiotics. After he is stabilized, what is the most appropriate next step in management?
Streptococcus bovis bacteremia is associated with colorectal cancer; this patient needs a colonoscopy when he is stable
Iron-deficiency anemia is particularly concerning for colon cancer in which patient population?
Men and postmenopausal women
What is the prognosis for a patient found to have familial adenomatous polyposis?
100% of patients will develop colon cancer if the colon is not removed
What are the two major molecular pathways that lead to colorectal cancer?
The microsatellite instability and chromosomal instability pathways
In the microsatellite instability pathway, what type of mutation is responsible for carcinogenesis in colonic epithelium?
DNA mismatch repair mutation
Loss of function of which gene leads to decreased intracellular adhesion in the colonic epithelium?
KRAS gene mutation leads to dysregulation of what cellular function?
Signal transduction; the cell will respond abnormally to growth factors, contributing to tumorigenesis
True or False? Loss of the APC gene will lead to adenoma formation.
False. Both APC and KRAS gene mutation must be present for adenoma formation
Sporadic mutation leading to loss of function of which tumor suppressor gene is often the last step in malignant transformation of colonic epithelial cells?
Carcinoid tumors are malignancies of which type of cell?
Carcinoid tumors are derived from endocrine cells
What percentage of small bowel tumors are carcinoid tumors?
What is the most common site of a carcinoid tumor?
The small intestine
What are the presenting symptoms of carcinoid tumor confined to the small intestine?
None; carcinoid syndrome only occurs once the tumor metastasizes to the liver
What are the classic presenting symptoms of carcinoid syndrome?
Flushing, wheezing, diarrhea, right-sided heart murmurs
What finding is seen on electron microscopy in carcinoid tumors?
Dense core bodies; these are secretory vesicles containing serotonin
Explain why a patient does not present with carcinoid syndrome when a carcinoid tumor is confined to the gastrointestinal tract.
The patient would not present with carcinoid syndrome because the liver metabolizes serotonin on the first pass and it does not reach systemic circulation
Describe the pathogenesis of cirrhosis.
Destruction of hepatocytes results in diffuse fibrosis; cells regenerate in nodular pattern, destroying normal architecture
Cirrhosis can be further characterized as being either _____ or _____, depending on the etiology of the liver injury.
Micronodular cirrhosis is often the result of what category of liver damage?
Metabolic insult such as from alcohol, hemochromatosis, or Wilson#039;s disease
Macronodular cirrhosis is usually the result of significant liver injury leading to _____ _____.
Give two examples of disease processes that typically lead to macronodular cirrhosis.
Postinfectious hepatitis and drug-induced hepatitis
Which form of cirrhosis is most associated with an increased risk of hepatocellular carcinoma: micronodular or macronodular?
A surgical portacaval shunt allows blood to flow between the _____ _____ and the _____ _____ _____.
Splenic vein; left renal vein
In patients with cirrhosis and portal hypertension, melena may be the result of bleeding from either _____ _____ or _____ _____.
Esophageal varices; peptic ulcers