Gastrointestinal Pathology Practice Questions

Q: All are true about the pathological changes in pseudomembranous enterocolitis, EXCEPT:

Rectal sparing is a feature. **Explanation:** Pseudomembranous enterocolitis (PMC) is an inflammatory condition of the colon, most commonly caused by toxins produced by **_Clostridioides difficile_** following broad-spectrum antibiotic use. **Why Option D is the Correct Answer (The Exception):** In pseudomembranous colitis, the involvement is typically diffuse. Unlike Crohn’s disease, which is characterized by "skip lesions" and frequent rectal sparing, **PMC usually involves the rectum.** In fact, sigmoidoscopy/proctoscopy is a primary diagnostic tool because the characteristic "volcano lesions" and yellowish-white plaques are readily visible in the rectum and sigmoid colon in the vast majority of cases. **Analysis of Incorrect Options:** * **Option A & B:** While the name suggests "enterocolitis," the disease is predominantly **confined to the colonic mucosa**. It typically involves the **entire colon** (pancolitis), although the severity of plaque formation may vary across segments. * **Option C:** The hallmark pathology involves focal surface **epithelial necrosis and erosion**. This is accompanied by an exudate of fibrin, neutrophils, and necrotic debris that erupts from the crypts (the "volcano" or "mushroom" lesion) to form the classic pseudomembrane. **High-Yield Clinical Pearls for NEET-PG:** * **Etiology:** Most common offending antibiotics are **Clindamycin**, Fluoroquinolones, and Cephalosporins. * **Morphology:** The "Volcano Lesion" is the pathognomonic histological feature. * **Diagnosis:** Gold standard is the **Cell Cytotoxicity Assay**; however, GDH antigen and Toxin A/B PCR are more commonly used in clinical practice. * **Treatment:** First-line therapy is oral **Vancomycin** or Fidaxomicin (Metronidazole is now secondary).

Q: Which of the following statements is NOT true regarding Gastrointestinal Stromal Tumors (GIST)?

Mutations in the ALK gene are observed in most cases.. **Explanation:** Gastrointestinal Stromal Tumors (GIST) are the most common mesenchymal neoplasms of the GI tract. The correct answer is **D** because GISTs are primarily driven by mutations in the **c-KIT (CD117)** gene (approx. 75–85%) or the **PDGFRA** gene (approx. 10%) [1]. Mutations in the *ALK* gene are characteristic of Inflammatory Myofibroblastic Tumors (IMT), not GIST. **Analysis of Options:** * **Option A:** True. GISTs originate from the **Interstitial Cells of Cajal (ICC)**, which serve as the electrical pacemakers of the gut located in the muscularis propria. * **Option B:** True. While overall rare compared to adenocarcinomas, GISTs are the most frequent mesenchymal (non-epithelial) tumors of the digestive system. * **Option C:** True. The clinical behavior and malignancy risk of GIST are determined by two primary factors: **Tumor size** and the **Mitotic count** (number of mitoses per 5 mm²) [1]. **High-Yield NEET-PG Pearls:** * **Most Common Site:** Stomach (60%), followed by the small intestine (30%). * **Immunohistochemistry (IHC) Marker:** **DOG1** (Discovered on GIST-1) is the most sensitive and specific marker, followed by **CD117 (c-KIT)**. * **Morphology:** Most show a spindle cell pattern; some show an epithelioid pattern. * **Treatment:** Surgical resection is the mainstay. For metastatic or unresectable cases, **Imatinib** (a tyrosine kinase inhibitor) is the drug of choice [1]. * **Carney Triad:** A rare association of GIST, pulmonary chondroma, and paraganglioma. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 782-784.

Question 1

All are true about the pathological changes in pseudomembranous enterocolitis, EXCEPT:

Accepted Answer

Rectal sparing is a feature

Answer

It is confined to the colonic mucosa

Answer

The whole colon is involved

Answer

The epithelium is eroded and necrotic in certain areas

Question 2

A 30-year-old lady presents with features of malabsorption and iron deficiency anemia. Duodenal biopsy shows complete villous atrophy. Which of the following antibodies is likely to be present?

Accepted Answer

Antiendomysial antibodies

Answer

Anti-goblet cell antibodies

Answer

Anti-Saccharomyces cerevisiae antibodies

Answer

Antineutrophil cytoplasmic antibodies

Question 3

Which of the following features distinguishes Necrotizing Sialometaplasia from squamous cell carcinoma?

Accepted Answer

Nests of squamous epithelium with several residual ductal lamina within them are noticed.

Answer

Majority of intraoral cases present with ulceration and pain in the later stages.

Answer

Varying degrees of lobar necrosis are seen.

Answer

Squamous metaplasia of excretory ducts and acini are noted.

Question 4

Which of the following is associated with H.pylori?

Accepted Answer

MALToma

Answer

Ulcerative colitis

Answer

Crohn disease

Answer

Celiac sprue

Question 5

Which of the following is NOT a predisposing factor for esophageal cancer?

Accepted Answer

Mediastinal fibrosis

Answer

Diverticula

Answer

Caustic alkali burn

Answer

HPV

Question 6

Most common type of malignancy of the stomach is:

Accepted Answer

Adenocarcinoma

Answer

Squamous carcinoma

Answer

Anaplastic carcinoma

Answer

Lymphoma

Question 7

In Hirschsprung disease, what is the characteristic state of the aganglionic segment?

Accepted Answer

Normal or contracted

Answer

Normal or dilated

Answer

Dilated or contracted

Answer

Always dilated

Question 8

All of the following are predisposing factors for squamous cell carcinoma of the esophagus EXCEPT?

Accepted Answer

Gastroesophageal reflux disease (GERD)

Answer

Achalasia

Answer

Tylosis palmaris

Answer

Alcohol

Question 9

Which of the following statements is NOT true regarding Gastrointestinal Stromal Tumors (GIST)?

Accepted Answer

Mutations in the ALK gene are observed in most cases.

Answer

They originate from the interstitial cells of Cajal.

Answer

They are the most common mesenchymal tumor of the gastrointestinal tract.

Answer

The prognosis is dependent on tumor size.

Question 10

Which of the following conditions is characterized by granulomatous inflammation?

Accepted Answer

Crohn's disease

Answer

Ulcerative colitis

Answer

Amoebiasis

Answer

Giardiasis

Gastrointestinal Pathology — MCQs

Gastrointestinal Pathology — MCQs

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