MD Gastrointestinal Tract Disorders 3 — Questions and Answers
Question 1: A 70-year-old man with a history of smoking and alcohol use presents with progressive dysphagia and a mid-esophageal mass. Biopsy shows squamous cell carcinoma. Which statement is true regarding this tumor?
- It arises most commonly in the lower third of the esophagus
- It is associated with Barrett's metaplasia
- It is most common in the middle and upper thirds of the esophagus (Correct answer)
- It has a better prognosis than esophageal adenocarcinoma
Correct answer: It is most common in the middle and upper thirds of the esophagus
Squamous cell carcinoma of the esophagus typically arises in the middle and upper thirds and is associated with smoking, alcohol, achalasia, and hot beverage consumption.
Question 2: A patient with cirrhosis develops acute upper GI bleeding. Endoscopy reveals tortuous, dilated submucosal veins at the gastroesophageal junction. What is the pathophysiologic mechanism?
- Increased arterial blood flow to the esophagus
- Portal hypertension causing portosystemic shunting (Correct answer)
- Aortoenteric fistula formation
- Mesenteric ischemia
Correct answer: Portal hypertension causing portosystemic shunting
Portal hypertension from cirrhosis causes blood to shunt through portosystemic collaterals including esophageal varices, which are prone to rupture.
Question 3: A 55-year-old woman presents with episodic right upper quadrant pain, nausea, and jaundice following fatty meals. Ultrasound shows gallstones. Which composition of gallstones is most common in the United States?
- Pigment (black) stones
- Cholesterol stones (Correct answer)
- Pigment (brown) stones
- Calcium bilirubinate stones
Correct answer: Cholesterol stones
Cholesterol gallstones account for approximately 80% of gallstones in the US and are associated with obesity, female sex, pregnancy, and rapid weight loss.
Question 4: A 40-year-old man with recurrent kidney stones is found to have hypercalcemia and nephrolithiasis. He also complains of abdominal pain and peptic ulcers. What syndrome should be suspected?
- Zollinger-Ellison syndrome
- Multiple Endocrine Neoplasia type 1 (MEN1) (Correct answer)
- Carcinoid syndrome
- VIPoma
Correct answer: Multiple Endocrine Neoplasia type 1 (MEN1)
MEN1 (Wermer syndrome) involves tumors of the parathyroids, pancreatic islets (including gastrinomas causing peptic ulcers), and pituitary gland.
Question 5: A 28-year-old man presents with profuse watery diarrhea (rice-water stools) after returning from Southeast Asia. He is severely dehydrated. What organism is most likely responsible?
- Shigella dysenteriae
- Salmonella typhi
- Vibrio cholerae (Correct answer)
- Giardia lamblia
Correct answer: Vibrio cholerae
Vibrio cholerae produces cholera toxin that causes ADP-ribosylation of Gs protein, leading to massive secretory diarrhea with characteristic rice-water appearance.
Question 6: A 50-year-old man undergoes total gastrectomy for gastric cancer. Which nutritional deficiency will he inevitably develop without supplementation?
- Iron deficiency anemia only
- Folate deficiency
- Vitamin B12 deficiency (Correct answer)
- Vitamin D deficiency
Correct answer: Vitamin B12 deficiency
Total gastrectomy eliminates production of intrinsic factor by parietal cells, making it impossible to absorb vitamin B12 via the ileal receptor, necessitating parenteral supplementation.
Question 7: A patient with celiac disease continues to have diarrhea despite strict gluten avoidance. Repeat small bowel biopsy shows persistent villous atrophy. What complication should be most urgently considered?
- Irritable bowel syndrome superimposition
- Enteropathy-associated T-cell lymphoma (Correct answer)
- Microscopic colitis
- Pernicious anemia
Correct answer: Enteropathy-associated T-cell lymphoma
Refractory celiac disease that does not respond to a gluten-free diet raises concern for enteropathy-associated T-cell lymphoma, a serious malignant complication.
MD Gastrointestinal Tract Disorders 3
A 70-year-old man with a history of smoking and alcohol use presents with progressive dysphagia and a mid-esophageal mass.
Biopsy shows squamous cell carcinoma.
Which statement is true regarding this tumor?