Gastrointestinal Pathology Practice Questions

Q: A 50-year-old male presents with obstructive symptoms. Biopsy of the stomach reveals a Gastrointestinal stromal tumor (GIST). Which is the most appropriate immunohistochemical marker for GIST?

CD 117. **Explanation:** **Gastrointestinal Stromal Tumor (GIST)** is the most common mesenchymal tumor of the gastrointestinal tract, most frequently occurring in the stomach. These tumors originate from the **Interstitial Cells of Cajal (ICC)**, which serve as the GI pacemaker cells. **1. Why CD 117 is the Correct Answer:** The hallmark of GIST is the mutation in the **c-KIT proto-oncogene**, which encodes a transmembrane tyrosine kinase receptor. **CD 117** is the immunohistochemical (IHC) marker for the c-KIT protein. Approximately 95% of GISTs are positive for CD 117, making it the "gold standard" for diagnosis. Another highly sensitive and specific marker often used alongside CD 117 is **DOG1** (Discovered On GIST 1). **2. Analysis of Incorrect Options:** * **CD 34:** While positive in about 60-70% of GISTs, it is non-specific as it also marks vascular tumors and solitary fibrous tumors. * **CD 30:** This is a marker for Reed-Sternberg cells in Hodgkin Lymphoma and Anaplastic Large Cell Lymphoma (ALCL). * **CD 10:** Also known as CALLA, it is primarily used to identify Acute Lymphoblastic Leukemia (ALL) and certain renal/endometrial tumors. **3. High-Yield Clinical Pearls for NEET-PG:** * **Genetic Mutation:** Most common is **c-KIT**; if c-KIT is negative, look for **PDGFRA** (Platelet-Derived Growth Factor Receptor Alpha) mutations [1]. * **Histology:** Can show spindle cell (most common) or epithelioid morphology. * **Treatment:** The targeted therapy of choice is **Imatinib** (a tyrosine kinase inhibitor) [1]. * **Carney Triad:** 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. 782-783.

Q: A 40-year-old tobacco chewer presented for a routine oral examination. A non-scrapable white patch was noticed on the left buccal mucosa. What is the most likely diagnosis for this lesion?

Premalignant lesion. **Explanation:** The clinical presentation of a **non-scrapable white patch** on the oral mucosa in a patient with a history of tobacco chewing is the classic definition of **Leukoplakia**. According to the WHO, leukoplakia is a clinical term used when a white patch cannot be characterized clinically or pathologically as any other disease. **1. Why "Premalignant Lesion" is correct:** A **Premalignant Lesion** (e.g., Leukoplakia, Erythroplakia) is a morphologically altered tissue in which cancer is more likely to occur than in its apparently normal counterpart. It is a localized change. In this case, the specific patch on the buccal mucosa represents the site of potential malignant transformation. **2. Why other options are incorrect:** * **Premalignant Condition:** This refers to a generalized systemic state associated with a significantly increased risk of cancer (e.g., Oral Submucous Fibrosis, Lichen Planus, Xeroderma Pigmentosum). Unlike a lesion, a condition involves the entire mucosa or system, not just a localized patch. * **Normal variation/Developmental disorder:** These would typically be asymptomatic, bilateral, or present since birth (e.g., Fordyce spots or Leukoedema) and are not associated with tobacco use. **Clinical Pearls for NEET-PG:** * **Leukoplakia:** The most common premalignant lesion of the oral cavity. The "speckled" (erythroleukoplakia) variety has the highest risk of malignant transformation. * **Erythroplakia:** A red, velvety patch; it has a much higher malignant potential than leukoplakia. * **Biopsy Rule:** Any white patch that persists for more than 2 weeks after removing local irritants (like tobacco) must be biopsied to rule out squamous cell carcinoma.

Q: Which of the following is NOT a high-grade salivary gland malignancy?

Basal cell adenocarcinoma. **Explanation:** Salivary gland malignancies are classified into low, intermediate, and high grades based on their clinical behavior, histological features, and metastatic potential. **1. Why Basal Cell Adenocarcinoma is the correct answer:** Basal cell adenocarcinoma is considered a **low-grade malignancy**. It is the malignant counterpart of basal cell adenoma. While it is locally invasive and can recur, it has a low rate of distant metastasis and an excellent prognosis (over 90% 10-year survival rate). It should not be confused with high-grade entities. **2. Analysis of Incorrect Options:** * **Mucoepidermoid Carcinoma (MEC):** This is the most common malignant salivary gland tumor. While it can be low-grade, it frequently presents as a **high-grade** tumor (especially in the parotid), characterized by rapid growth and early metastasis. * **Adenoid Cystic Carcinoma (ACC):** This is a **high-grade** malignancy known for its relentless growth, **perineural invasion** (causing pain/palsy), and "Swiss-cheese" appearance. It has a high propensity for late distant metastasis (especially to the lungs). * **Salivary Duct Carcinoma:** This is a highly aggressive, **high-grade** malignancy that histologically resembles high-grade ductal carcinoma of the breast. It carries a very poor prognosis. **High-Yield Clinical Pearls for NEET-PG:** * **Most common salivary tumor (overall):** Pleomorphic Adenoma. * **Most common malignant salivary tumor:** Mucoepidermoid Carcinoma. * **Tumor with highest incidence of perineural invasion:** Adenoid Cystic Carcinoma. * **Hot Spot:** The **Parotid gland** is the most common site for salivary tumors, but the **Sublingual gland** has the highest *percentage* of tumors being malignant (approx. 80%).

Q: What is the primary pathophysiological basis of achalasia cardia?

Absence of nerves. **Explanation:** **1. Why "Absence of nerves" is correct:** Achalasia cardia is a primary esophageal motility disorder characterized by the failure of the Lower Esophageal Sphincter (LES) to relax and the absence of peristalsis in the distal esophagus. The fundamental pathophysiology is the **selective loss (absence) of inhibitory postganglionic neurons** in the **Myenteric (Auerbach’s) plexus**. Specifically, there is a depletion of neurons that release Nitric Oxide (NO) and Vasoactive Intestinal Peptide (VIP), which are essential for LES relaxation. This neurogenic loss leads to an unopposed excitatory stimulus, resulting in a hypertensive, non-relaxing LES. **2. Why the other options are incorrect:** * **Absence of muscles:** The muscular layers (circular and longitudinal) are anatomically present. The pathology is functional/neurological, not a structural absence of muscle tissue. * **Hypertrophy of nerves:** There is a degeneration and decrease in the number of ganglion cells, not an overgrowth or hypertrophy. * **Hypertrophy of muscles:** While chronic obstruction may lead to compensatory thickening of the esophageal wall in some cases, it is a *secondary* effect and not the primary pathophysiological basis. **Clinical Pearls for NEET-PG:** * **Gold Standard Investigation:** Esophageal Manometry (shows incomplete LES relaxation and aperistalsis). * **Barium Swallow Sign:** "Bird’s beak" or "Rat-tail" appearance. * **Chagas Disease:** A common secondary cause of achalasia (due to *Trypanosoma cruzi*). * **Treatment of Choice:** Laparoscopic Heller’s Cardiomyotomy (often with a partial fundoplication). * **Triad of Achalasia:** Dysphagia (to both solids and liquids), Regurgitation, and Weight loss.

Q: Which of the following is true regarding Barrett's esophagus?

It is a premalignant condition.. Barrett’s Esophagus is a condition where the normal stratified squamous epithelium of the lower esophagus is replaced by simple columnar epithelium with goblet cells (intestinal metaplasia). This occurs as a protective response to chronic acid exposure in Gastroesophageal Reflux Disease (GERD). 1. Why Option B is Correct: Barrett’s esophagus is a well-established premalignant condition. The metaplastic columnar cells can undergo dysplasia, significantly increasing the risk of developing Esophageal Adenocarcinoma (approximately 30–40 times higher risk than the general population). [1] 2. Why Other Options are Incorrect: * Option A: While it starts as a compensatory change, it is not considered "benign" in a clinical sense due to its high malignant potential. * Option C: It involves columnar metaplasia, not squamous. The squamous epithelium is what is being replaced. * Option D: Medical treatment (High-dose Proton Pump Inhibitors) is crucial to manage GERD symptoms and potentially slow the progression of dysplasia, though it may not always reverse existing metaplasia. High-Yield Clinical Pearls for NEET-PG: * Endoscopic Appearance: Characterized by "salmon-pink" velvety mucosa extending upwards from the gastroesophageal junction (Z-line). * Histology Gold Standard: Presence of Goblet cells on biopsy is diagnostic of intestinal metaplasia. * Cancer Association: Barrett’s is the strongest risk factor for Adenocarcinoma (typically involving the lower 1/3rd of the esophagus), whereas smoking and alcohol are linked to Squamous Cell Carcinoma (typically upper/middle 2/3rd). * Surveillance: Patients require periodic endoscopy with "Seattle protocol" biopsies; endoscopic ablative techniques like radiofrequency ablation (RFA) have largely supplanted the role of esophagectomy for high-grade dysplasia. [1]

Question 1

Barrett's esophagus can result from which of the following conditions?

Accepted Answer

Gastroesophageal reflux

Answer

Helicobacter pylori infection

Answer

Herpes simplex infection

Answer

Esophageal varices

Question 2

A 50-year-old male presents with obstructive symptoms. Biopsy of the stomach reveals a Gastrointestinal stromal tumor (GIST). Which is the most appropriate immunohistochemical marker for GIST?

Accepted Answer

CD 117

Answer

CD 34

Answer

CD 30

Answer

CD 10

Question 3

An endoscopic biopsy from a case of H. pylori related duodenal ulcer is most likely to reveal what histological finding?

Accepted Answer

Antral predominant gastritis

Answer

Multifocal atrophic gastritis

Answer

Acute erosive gastritis

Answer

Gastric atrophy

Question 4

A 40-year-old tobacco chewer presented for a routine oral examination. A non-scrapable white patch was noticed on the left buccal mucosa. What is the most likely diagnosis for this lesion?

Accepted Answer

Premalignant lesion

Answer

Normal variation of the mouth

Answer

Developmental disorder

Answer

Premalignant condition

Question 5

Which of the following is NOT a high-grade salivary gland malignancy?

Accepted Answer

Basal cell adenocarcinoma

Answer

Mucoepidermoid carcinoma

Answer

Adenoid cystic carcinoma

Answer

Salivary duct carcinoma

Question 6

A 16-year-old boy presents with a 24-hour history of severe abdominal pain, nausea, vomiting, and low-grade fever. The pain is initially periumbilical in location but has migrated to the right lower quadrant of the abdomen, with maximal tenderness elicited at McBurney point. The leukocyte count is 14,000/mm3, with 74% segmented neutrophils and 12% bands. Surgery is performed. Which of the following describes the expected findings at the affected site?

Accepted Answer

Prominent areas of edema, congestion, and a purulent reaction with localized areas of abscess formation

Answer

Fistula connecting to the abdominal wall

Answer

Granulomatous inflammation with prominent aggregates of epithelioid cells and multinucleated giant cells

Answer

Massive infiltration of lymphocytes and plasma cells

Question 7

What is the primary pathophysiological basis of achalasia cardia?

Accepted Answer

Absence of nerves

Answer

Absence of muscles

Answer

Hypertrophy of nerves

Answer

Hypertrophy of muscles

Question 8

Which of the following is true regarding Barrett's esophagus?

Accepted Answer

It is a premalignant condition.

Answer

It is a benign condition.

Answer

It involves squamous metaplasia of the lower esophagus.

Answer

Medical treatment is not useful.

Question 9

Which of the following is NOT seen in carcinoid syndrome?

Accepted Answer

Constipation

Answer

Diarrhoea

Answer

Liver metastasis

Answer

5-HT secretion

Question 10

Precancerous potential in Plummer-Vinson syndrome may be due to which change in the epithelium?

Accepted Answer

Atrophy

Answer

Hypertrophy

Answer

Acanthosis

Answer

All the above

Gastrointestinal Pathology — MCQs

Gastrointestinal Pathology — MCQs

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