Gastrointestinal Pathology Practice Questions

Q: Ulceration of Peyer's patches occurs in which infection?

Salmonella infection. **Explanation:** The correct answer is **Salmonella infection (Typhoid fever)**. **Salmonella typhi** and **paratyphi** have a specific tropism for lymphoid tissue. After ingestion, the bacteria invade the intestinal mucosa and proliferate within the **Peyer’s patches** (lymphoid follicles) of the terminal ileum [1]. This leads to marked hyperplasia, followed by necrosis and sloughing of the overlying mucosa, resulting in characteristic **longitudinal ulcers** that follow the long axis of the bowel. This is a high-yield distinction from other types of intestinal ulceration. **Why other options are incorrect:** * **Amoebiasis (Entamoeba histolytica):** Typically causes **"flask-shaped" ulcers** with narrow necks and broad bases. These ulcers are usually found in the colon (cecum and rectosigmoid) rather than Peyer's patches. * **Crohn’s disease:** Characterized by **transmural inflammation**, "aphthous" ulcers that progress to **"cobblestone" appearance**, and non-caseating granulomas. It is not specifically localized to lymphoid follicles. * **Clostridium difficile:** Causes **Pseudomembranous colitis**. It is characterized by "volcano-like" eruptions of purulent exudate (fibrin, mucus, and neutrophils) forming a yellow-green membrane over the colonic mucosa, rather than discrete ulceration of Peyer's patches. **NEET-PG High-Yield Pearls:** * **Typhoid Ulcers:** Longitudinal, located in the ileum; risk of perforation is highest in the 3rd week [1]. * **Tubercular Ulcers:** Transverse (circumferential) due to spread via lymphatics. * **Widal Test:** Measures antibodies against O and H antigens; usually becomes positive in the 2nd week of Typhoid fever. * **Microscopy:** Look for **"Typhoid cells"** (erythrophagocytic macrophages) in the liver, spleen, and bone marrow [1]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Alimentary System Disease, pp. 362-363.

Q: Which of the following is NOT a cause of stress-related mucosal injury?

Helicobacter pylori. **Explanation:** Stress-related mucosal injury (SRMI) refers to acute gastric mucosal lesions that develop in patients under severe physiological stress. The underlying pathophysiology involves **splanchnic hypoperfusion**, which leads to mucosal ischemia, reduced bicarbonate production, and a breakdown of the protective mucosal barrier. **Why B is the correct answer:** * **Helicobacter pylori:** This is a chronic colonizer of the gastric antrum. While it is the primary cause of **chronic antral gastritis** and **peptic ulcer disease (PUD)**, it is not a cause of acute stress-related injury. SRMI is triggered by systemic physiological collapse, whereas *H. pylori* damage is mediated by chronic inflammation and urease production. **Why the other options are incorrect:** * **A. Head Injury:** Specifically associated with **Cushing’s Ulcers**. Increased intracranial pressure stimulates the vagus nerve, leading to gastric acid hypersecretion. * **C. Severe Burns:** Associated with **Curling’s Ulcers**. Significant fluid loss leads to reduced plasma volume and gastric mucosal ischemia. * **D. Sepsis:** A classic cause of SRMI due to the release of inflammatory mediators and systemic hypotension, which compromises the gastric microcirculation. **High-Yield Clinical Pearls for NEET-PG:** * **Curling’s Ulcer:** Seen in **Burns** (Think: Curling iron causes burns). * **Cushing’s Ulcer:** Seen in **CNS** injury/Head trauma (Think: Cushing = CNS). * **Location:** Stress ulcers are typically multiple, shallow, and found in the **acid-secreting portions (fundus and body)** of the stomach, unlike chronic PUD which is often solitary and found in the antrum or duodenum. * **Prophylaxis:** Indicated for high-risk patients (e.g., mechanical ventilation >48 hours, coagulopathy).

Q: A 53-year-old woman complains of acute diarrhea and severe abdominal pain. She was recently treated with broad-spectrum antibiotics for community-acquired pneumonia. A CBC shows a WBC count of 24,000/mL. The patient subsequently develops septic shock and dies. A portion of her colon is shown at autopsy. These findings are typical of which of the following gastrointestinal diseases?

Pseudomembranous colitis. ***Pseudomembranous colitis*** - Recent **broad-spectrum antibiotic** use leading to **Clostridioides difficile** overgrowth, presenting with acute diarrhea and septic shock is classic for pseudomembranous colitis. - Autopsy shows characteristic **yellowish-white pseudomembranes** adhering to the colonic mucosa, formed by fibrin, mucus, and inflammatory cells. *Crohn disease* - This is a **chronic granulomatous** inflammatory bowel disease with transmural inflammation and **skip lesions**. - Does not typically present as acute post-antibiotic diarrhea with septic shock and lacks the characteristic pseudomembrane formation. *Diverticulitis* - Involves inflammation of **diverticular pouches** with **pericolonic** fat stranding and potential abscess formation. - Does not cause diffuse colonic pseudomembrane formation and is not associated with recent antibiotic use in this acute manner. *Ischemic colitis* - Results from **vascular compromise** leading to mucosal necrosis, typically in **watershed areas** like the splenic flexure. - Presents with bloody diarrhea and shows hemorrhagic necrosis rather than pseudomembrane formation on gross examination.

Q: Each of the following cysts is associated with an impacted tooth except:

Primordial cyst. ### Explanation The key to answering this question lies in understanding the **origin** of the cyst relative to the tooth germ. **Why Primordial Cyst is the correct answer:** A **Primordial cyst** develops **in place of a tooth** rather than being associated with an existing impacted one. It arises from the degeneration of the enamel organ before any mineralized dental tissues are formed. Therefore, the tooth that should have been there is **clinically missing** from the dental arch, and the cyst occupies its space. **Analysis of Incorrect Options:** * **Dentigerous Cyst (Follicular Cyst):** This is the most common cyst associated with an impacted tooth. It originates from the reduced enamel epithelium and attaches to the **cemento-enamel junction (CEJ)**, enclosing the crown of an unerupted tooth (most commonly the mandibular 3rd molar). * **Calcifying Epithelial Odontogenic Cyst (Gorlin Cyst):** This is a rare odontogenic lesion that can be associated with an impacted tooth in about 25-30% of cases. It is characterized by "ghost cells" on histology. * **Odontogenic Keratocyst (OKC):** While OKCs can occur anywhere, a significant percentage (approx. 25-40%) are found in a "dentigerous relationship," surrounding the crown of an impacted tooth, particularly in the molar-ramus area of the mandible. **NEET-PG High-Yield Pearls:** 1. **Most common odontogenic cyst:** Radicular cyst (inflammatory). 2. **Most common developmental odontogenic cyst:** Dentigerous cyst. 3. **OKC Hallmark:** High recurrence rate, associated with **Gorlin-Goltz Syndrome** (PTCH gene mutation), and shows "picket fence" or "tombstone" appearance of the basal layer. 4. **Radiographic feature of Dentigerous cyst:** Well-defined unilocular lucency attached to the neck of an impacted tooth.

Question 1

H. pylori infection causes carcinoma by which mechanism?

Accepted Answer

Gastric metaplasia

Answer

Production of nitrosamines

Answer

Increasing acid secretion

Answer

Causing mutation

Question 2

All of the following statements are false, except?

Accepted Answer

Ulcerative colitis involves mucosa and submucosa

Answer

Collagenous colitis is seen in children

Answer

Ulcerative colitis is an acute granulomatous disease

Answer

Necrotizing enterocolitis is an acute granulomatous disease

Question 3

What is the single most important prognostic indicator of colorectal carcinoma?

Accepted Answer

Extent of tumor

Answer

CEA titres

Answer

Degree of atypia

Answer

Size of tumor

Question 4

Ulceration of Peyer's patches occurs in which infection?

Accepted Answer

Salmonella infection

Answer

Amoebiasis

Answer

Crohn's disease

Answer

Clostridium difficile infection

Question 5

Which of the following is NOT a cause of stress-related mucosal injury?

Accepted Answer

Helicobacter pylori

Answer

Head injury

Answer

Severe burns

Answer

Sepsis

Question 6

Which of the following is a true statement about Barrett's Esophagus?

Accepted Answer

Chronic reflux is a cause.

Answer

It is non-premalignant.

Answer

It progresses to squamous cell carcinoma.

Answer

It is irreversible.

Question 7

A 53-year-old woman complains of acute diarrhea and severe abdominal pain. She was recently treated with broad-spectrum antibiotics for community-acquired pneumonia. A CBC shows a WBC count of 24,000/mL. The patient subsequently develops septic shock and dies. A portion of her colon is shown at autopsy. These findings are typical of which of the following gastrointestinal diseases?

Accepted Answer

Pseudomembranous colitis

Answer

Crohn disease

Answer

Diverticulitis

Answer

Ischemic colitis

Question 8

Each of the following cysts is associated with an impacted tooth except:

Accepted Answer

Primordial cyst

Answer

Dentigerous cyst

Answer

Calcifying epithelial odontogenic cyst

Answer

Keratocyst

Question 9

Carcinoid tumors are known to secrete which of the following substances?

Accepted Answer

5-HT (Serotonin)

Answer

Histamine

Answer

VMA (Vanillylmandelic acid)

Answer

Bradykinin

Question 10

Which of the following statements about Barrett's esophagus are true?

Accepted Answer

Metaplasia, leads to adenocarcinoma, and long esophageal segment involved are true, while peptic ulcer and paraesophageal hernia are false.

Answer

Metaplasia, peptic ulcer, and paraesophageal hernia are true, while leads to adenocarcinoma and long esophageal segment involved are false.

Answer

Metaplasia, leads to adenocarcinoma are true, while peptic ulcer, paraesophageal hernia, and long esophageal segment involved are false.

Answer

Metaplasia and peptic ulcer are true, while paraesophageal hernia, leads to adenocarcinoma, and long esophageal segment involved are false.

Gastrointestinal Pathology — MCQs

Gastrointestinal Pathology — MCQs

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