Gastrointestinal Pathology Practice Questions

Q: Long arm chromosome 5 deletion is seen in which of the following conditions?

Polyposis coli. **Explanation:** **Correct Answer: C. Polyposis coli** Familial Adenomatous Polyposis (FAP), or Polyposis coli, is an autosomal dominant condition characterized by the development of hundreds to thousands of adenomatous colonic polyps [1]. The underlying genetic defect is a mutation or deletion in the **APC (Adenomatous Polyposis Coli) gene**, which is located on the **long arm of chromosome 5 (5q21)**. The APC gene is a tumor suppressor gene that regulates the Wnt signaling pathway; its loss leads to the accumulation of β-catenin, promoting cellular proliferation and the "adenoma-carcinoma sequence." **Analysis of Incorrect Options:** * **A & B. Crohn's disease and Ulcerative Colitis:** These are Inflammatory Bowel Diseases (IBD). While they have a genetic predisposition (e.g., *NOD2/CARD15* mutations on chromosome 16 for Crohn’s), they are not primarily associated with 5q deletions. * **D. Pheochromocytoma:** This neuroendocrine tumor is associated with mutations in genes like *RET* (Chr 10), *VHL* (Chr 3), *NF1* (Chr 17), and *SDHB/D* (Chr 1/11). It is not linked to chromosome 5q. **High-Yield Clinical Pearls for NEET-PG:** * **Gardner Syndrome:** FAP + Osteomas (mandible) + Soft tissue tumors (desmoid tumors) + Dental abnormalities. * **Turcot Syndrome:** FAP + Central Nervous System tumors (Medulloblastoma). * **Rule of 100s:** In FAP, >100 polyps are required for diagnosis, and the risk of progression to colorectal carcinoma is nearly **100%** by age 40 if a prophylactic colectomy is not performed [1]. * **Screening:** Annual sigmoidoscopy starting at age 10-12 for at-risk family members. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 821-822.

Q: What is the most common type of gastric tumor in adults?

Adenocarcinoma. **Explanation:** **Adenocarcinoma** is the most common type of gastric tumor, accounting for approximately **90–95%** of all malignant gastric neoplasms in adults. It originates from the glandular epithelium of the gastric mucosa. Risk factors include *H. pylori* infection, smoking, high salt intake, and chronic atrophic gastritis. **Analysis of Incorrect Options:** * **Stromal tumor (GIST):** While Gastrointestinal Stromal Tumors are the most common mesenchymal tumors of the GI tract, they account for only about 1–3% of all gastric malignancies. They originate from the interstitial cells of Cajal. * **Lymphoma:** The stomach is the most common site for extranodal lymphomas (predominantly MALToma and DLBCL), but these represent only about 1–5% of gastric cancers. * **Leiomyosarcoma:** These are rare smooth muscle malignancies. Most tumors previously classified as leiomyosarcomas are now identified as GISTs through immunohistochemistry (CD117/c-kit positivity). **High-Yield Clinical Pearls for NEET-PG:** * **Lauren Classification:** Divides gastric adenocarcinoma into **Intestinal** (associated with environmental factors/metaplasia) and **Diffuse** (associated with younger age and Signet ring cells). * **Virchow’s Node:** Left supraclavicular lymphadenopathy, a classic sign of metastatic gastric cancer. * **Sister Mary Joseph Nodule:** Periumbilical metastasis. * **Krukenberg Tumor:** Metastasis to the ovaries (classically from the diffuse type). * **Investigation of Choice:** Upper GI Endoscopy with biopsy.

Q: Which of the following colonic polyps has the highest potential for malignant transformation?

Adenomatous polyp. **Explanation:** The malignant potential of a colonic polyp is determined by its histological characteristics. **Adenomatous polyps** are true neoplastic proliferations and are considered precursors to colorectal carcinoma via the **adenoma-carcinoma sequence**. The risk of malignancy within an adenoma depends on three factors: size (>2 cm), histological type (villous > tubulovillous > tubular), and the degree of dysplasia. Among these, **villous adenomas** have the highest risk of harboring invasive carcinoma (up to 40%). **Analysis of Incorrect Options:** * **Juvenile Polyps:** These are typically hamartomatous lesions found in children. While they can bleed, solitary juvenile polyps have no malignant potential. (Note: Juvenile Polyposis *Syndrome* increases cancer risk due to associated adenomatous changes, but the polyp itself is benign). * **Hyperplastic Polyps:** These are the most common non-neoplastic polyps, usually found in the rectosigmoid. They result from decreased cell shedding and generally carry no malignant potential (except for the distinct "sessile serrated" pathway). * **Hamartomatous Polyps:** These are composed of native tissue elements arranged in a disorganized mass (e.g., Peutz-Jeghers syndrome). They are benign, though the underlying genetic syndromes may predispose patients to extra-colonic malignancies. **High-Yield Pearls for NEET-PG:** * **Most common site for polyps:** Sigmoid colon. * **Most common histological type of Adenoma:** Tubular adenoma (but Villous has higher malignant risk). * **Gardner Syndrome:** Adenomatous polyps + Osteomas + Soft tissue tumors (Desmoids). * **Turcot Syndrome:** Adenomatous polyps + CNS tumors (Medulloblastoma/Glioma). * **Screening:** Colonoscopy is the gold standard for both detection and therapeutic polypectomy.

Q: What is the most common site of GIST?

Stomach. **Explanation:** **Gastrointestinal Stromal Tumor (GIST)** is the most common mesenchymal tumor of the gastrointestinal tract. It originates from the **Interstitial Cells of Cajal (ICC)**, which are the pacemaker cells located in the muscularis propria. **Why Stomach is Correct:** The stomach is the most frequent site of occurrence, accounting for approximately **60%** of all GIST cases. These tumors are typically driven by gain-of-function mutations in the **c-KIT (CD117)** tyrosine kinase gene (80%) or the **PDGFRA** gene [1]. **Analysis of Incorrect Options:** * **Ileum (Small Intestine):** This is the second most common site, accounting for about **25-30%** of cases. While common, it is significantly less frequent than the stomach [1]. * **Esophagus & Colon:** These are rare sites for GIST, each accounting for less than **5%** of cases. GISTs in the rectum are slightly more common than in the colon but still far less frequent than gastric GISTs. **High-Yield Clinical Pearls for NEET-PG:** * **Immunohistochemistry (IHC) Marker:** **CD117 (c-KIT)** is the most sensitive and specific marker. **DOG1** (Discovered On GIST 1) is another highly specific marker used in KIT-negative cases. * **Histology:** Most GISTs show a **spindle cell** pattern (70%), followed by an epithelioid pattern. * **Treatment:** The targeted therapy of choice is **Imatinib mesylate**, a tyrosine kinase inhibitor [1]. * **Prognostic Factors:** The risk of malignancy is determined by **tumor size** and **mitotic count** (Mitotic index) [1]. **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

Long arm chromosome 5 deletion is seen in which of the following conditions?

Accepted Answer

Polyposis coli

Answer

Crohn's disease

Answer

Ulcerative colitis

Answer

Pheochromocytoma

Question 2

Microdeletion leading to instability of DNA, causing the cell to undergo degeneration, is seen as a marker in which of the following cancers?

Accepted Answer

Colon carcinoma

Answer

Medullary carcinoma of thyroid

Answer

Small cell lung cancer

Answer

Gastric lymphoma

Question 3

Which of the following statements is NOT true regarding pseudomembranous colitis?

Accepted Answer

Clostridium difficile is the only causative agent.

Answer

It can be associated with antibiotic use, for example, with third-generation cephalosporins.

Answer

It is characterized by the presence of pseudomembranes at the site of mucosal injury.

Answer

It typically presents with watery diarrhea, abdominal pain, and fever.

Question 4

Hypergastrinemia with hypochlorhydria is seen in which condition?

Accepted Answer

Pernicious anemia

Answer

Zollinger Ellison Syndrome

Answer

VIPoma

Answer

Glucagonoma

Question 5

What is the most common type of gastric tumor in adults?

Accepted Answer

Adenocarcinoma

Answer

Stromal tumor

Answer

Leiomyosarcoma

Answer

Lymphoma

Question 6

Which of the following colonic polyps has the highest potential for malignant transformation?

Accepted Answer

Adenomatous polyp

Answer

Juvenile polyp

Answer

Hyperplastic polyp

Answer

Hamartomatous polyp

Question 7

What is the genetic abnormality associated with the progression from late adenoma to carcinoma in colorectal cancer?

Accepted Answer

p53

Answer

APC

Answer

K-ras

Answer

DCC

Question 8

Features of typhoid ulcers include all of the following EXCEPT?

Accepted Answer

Stricture and obstruction

Answer

Bleeding

Answer

Perforation

Answer

Longitudinal orientation

Question 9

What is the most common site of GIST?

Accepted Answer

Stomach

Answer

Ileum

Answer

Esophagus

Answer

Colon

Question 10

On rectal examination, a patient is found to have a large, fungating mass protruding into the rectal lumen. Biopsy of this mass demonstrates an invasive malignant tumor composed of glandular structures. The development of this condition is most strongly associated with which of the following?

Accepted Answer

Ulcerative colitis

Answer

Diverticulitis

Answer

Diverticulosis

Answer

Juvenile polyposis syndrome

Gastrointestinal Pathology — MCQs

Gastrointestinal Pathology — MCQs

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