Gastrointestinal Pathology Practice Questions

Q: Gastrointestinal stromal tumors (GIST) arise from mutations in which of the following genes?

c-KIT oncogene. **Gastrointestinal Stromal Tumors (GIST)** are the most common mesenchymal tumors of the abdomen. They originate from the **Interstitial Cells of Cajal (ICC)**, which serve as the electrical pacemakers of the gut. **1. Why c-KIT is correct:** Approximately 75–85% of GISTs are driven by an activating mutation in the **c-KIT oncogene** (CD117). This gene encodes a receptor tyrosine kinase. The mutation leads to constitutive activation of the kinase signaling pathway, resulting in uncontrolled cell proliferation [1]. In cases where c-KIT is not mutated, about 8% of GISTs harbor mutations in **PDGFRA** (Platelet-Derived Growth Factor Receptor Alpha) [1]. **2. Why the other options are incorrect:** * **Options B & C (c-KTT):** These are distractors. "c-KTT" is not a recognized oncogene; it is a common spelling trap used in competitive exams to test precision. * **Option D (c-RET):** The RET proto-oncogene is associated with **Multiple Endocrine Neoplasia (MEN) type 2A and 2B**, Medullary Thyroid Carcinoma, and Hirschsprung disease, but not GIST [2]. **High-Yield Clinical Pearls for NEET-PG:** * **Most common site:** Stomach (60%), followed by the small intestine (30%) [1]. * **Immunohistochemistry (IHC) Marker:** **DOG1** (Discovered On GIST 1) is the most sensitive and specific marker, especially in c-KIT negative cases. **CD117** is the standard diagnostic marker. * **Morphology:** Most GISTs show a **spindle cell** pattern (70%). * **Targeted Therapy:** **Imatinib mesylate**, a tyrosine kinase inhibitor, is the first-line treatment for unresectable or metastatic GIST. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 782-783. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, p. 292.

Question 1

Lymphoepithelial change in the stomach is seen in which condition?

Accepted Answer

MALToma

Answer

Coeliac disease

Answer

Ipsidoma

Answer

IBS

Question 2

Mucin is secreted by which organ?

Accepted Answer

Gall bladder

Answer

Skin

Answer

Lung

Answer

Stomach

Question 3

The presence of PAS-positive macrophages in the small intestine is a hallmark of which of the following conditions?

Accepted Answer

Whipple's disease

Answer

Crohn's disease

Answer

Celiac disease

Answer

Tropical sprue

Question 4

What is true about Carcinoid tumors?

Accepted Answer

Kulchitsky cell tumor

Answer

Always benign

Answer

Present with paroxysmal hypertension

Answer

Punch biopsy is diagnostic

Question 5

Angiodysplasia is typically seen in which location?

Accepted Answer

Right side of the colon

Answer

Stomach of an adult

Answer

Jejunum of a child

Answer

Left side of the colon

Question 6

What is the role of the thick mucous coat in the gastrointestinal tract?

Accepted Answer

It is protective in ulcer patients.

Answer

It is not protective in ulcer patients.

Answer

It is easily destroyed by antacids.

Answer

It is commonly associated with carcinomatous change.

Question 7

Gastrointestinal stromal tumors (GIST) arise from mutations in which of the following genes?

Accepted Answer

c-KIT oncogene

Answer

c-KTT oncogene

Answer

c-KTT oncogene

Answer

c-RET oncogene

Question 8

Which of the following is a marker for carcinoma of the colon?

Accepted Answer

CEA

Answer

AFP

Answer

CA-125

Answer

HCG

Question 9

Which of the following statements are true about gastric lymphoma?

Accepted Answer

Non-Hodgkin's lymphoma is the commonest variety.

Answer

Diagnosis is made by biopsy.

Answer

It is chemoresistant.

Answer

It is essentially of B-cell type.

Question 10

Histopathological findings in Whipple's disease include all of the following, except:

Accepted Answer

Marked increase in the number of intraepithelial lymphocytes

Answer

Marked increase in the number of macrophages in the mucosa

Answer

Dilatation of lymphatics in the mucosa

Answer

Lipid deposition in the mucosa

Gastrointestinal Pathology — MCQs

Gastrointestinal Pathology — MCQs

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