Gastrointestinal Pathology Practice Questions

Q: A 50-year-old male presents with obstructive symptoms. Biopsy of the stomach reveals a Gastrointestinal stromal tumor (GIST). What is the most appropriate 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. **Why CD 117 is the Correct Answer:** Approximately 95% of GISTs are positive for **CD 117**, which is the protein product of the **c-KIT proto-oncogene**. This gene encodes a transmembrane receptor tyrosine kinase. Mutations in c-KIT lead to constitutive activation of the kinase, driving tumor cell proliferation. CD 117 is considered the "gold standard" diagnostic marker and is essential for initiating targeted therapy with **Imatinib** (a tyrosine kinase inhibitor). **Analysis of Incorrect Options:** * **CD 34:** While positive in about 70% of GIST cases, it is less specific than CD 117 and is also expressed in various other mesenchymal tumors (e.g., Solitary Fibrous Tumor). * **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 as a marker for Acute Lymphoblastic Leukemia (ALL) and certain renal/endometrial tumors. **High-Yield Facts for NEET-PG:** * **DOG1 (Discovered On GIST 1):** This is a highly sensitive and specific marker, often positive even in CD 117-negative GISTs. * **Genetics:** Most GISTs have **c-KIT** mutations; a subset (especially gastric GISTs) may have **PDGFRA** mutations [1]. * **Histology:** Most common pattern is **Spindle cell** (70%), followed by Epithelioid. * **Staining:** GIST is typically negative for Desmin and S100 (helping differentiate it from Leiomyoma and Schwannoma). **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 782-783.

Q: What is the most common site of squamous cell carcinoma of the esophagus?

Middle third. **Explanation:** The esophagus is anatomically divided into three segments, and the distribution of malignancies varies significantly based on the histological type. **1. Why the Middle Third is Correct:** Historically and globally, **Squamous Cell Carcinoma (SCC)** is the most common histological type of esophageal cancer. Epidemiological studies and pathology textbooks (such as Robbins) consistently identify the **middle third (50%)** as the most frequent site for SCC, followed by the lower third (30%) and the upper third (20%) [1]. This predilection is attributed to the prolonged contact of carcinogens (tobacco, alcohol, and hot liquids) at the physiological points of narrowing within the mid-esophagus. **2. Analysis of Incorrect Options:** * **Upper Third (A):** While SCC can occur here, it is the least common site (approx. 20%). It is often associated with Plummer-Vinson syndrome. * **Lower Third (C):** This is the most common site for **Adenocarcinoma**, which typically arises from Barrett’s esophagus (metaplasia due to chronic GERD). While SCC can occur here (30%), it is not the *most* common site for SCC. * **Cardia (D):** This is the junction between the esophagus and stomach. Tumors here are almost exclusively adenocarcinomas, often categorized as gastric cardia cancers. **3. High-Yield Clinical Pearls for NEET-PG:** * **Most common esophageal cancer worldwide:** Squamous Cell Carcinoma. * **Most common esophageal cancer in the West/USA:** Adenocarcinoma (due to rising obesity and GERD). * **Risk Factors for SCC:** Smoking, Alcohol, Achalasia cardia, Tylosis, and Caustic injury. * **Morphology:** SCC often presents as a fungating (exophytic) mass or a circumferential infiltrative lesion leading to "bird-beak" appearance on barium swallow [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 766-767.

Q: Toxic megacolon is seen as a complication in which of the following conditions?

Ulcerative colitis. **Explanation:** **Toxic Megacolon** is a life-threatening complication characterized by total or segmental non-obstructive colonic dilatation (typically >6 cm) associated with systemic toxicity. **1. Why Ulcerative Colitis (UC) is correct:** While toxic megacolon can occur in any inflammatory process of the colon, it is most classically associated with **Ulcerative Colitis**. The underlying mechanism involves severe transmural inflammation (which is unusual for UC but occurs in fulminant cases). This inflammation leads to the release of inflammatory mediators and nitric oxide, which inhibit smooth muscle tone and damage the **myenteric plexus**, resulting in colonic paralysis, thinning of the wall, and rapid dilatation. In severe cases of UC, there is extension of inflammation into the main muscle coats and perforation may occur [1]. **2. Why other options are incorrect:** * **Crohn’s Disease:** Although it can cause toxic megacolon, it is much less common than in UC because the transmural fibrosis characteristic of Crohn’s often prevents the bowel from dilating significantly. * **Colonic Diverticulosis:** This is a structural abnormality (outpouchings). While it can lead to diverticulitis or perforation, it does not typically cause the acute toxic paralytic dilatation seen in megacolon. * **Miliary TB:** This involves hematogenous spread of tuberculosis. While intestinal TB exists (usually ileocecal), it typically presents with strictures or ulceration rather than acute toxic dilatation. **NEET-PG High-Yield Pearls:** * **Radiological Hallmark:** A plain X-ray abdomen showing a colonic diameter **>6 cm** (usually the transverse colon). * **Clinical Sign:** Sudden disappearance of bowel sounds and **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Alimentary System Disease, pp. 367-368.

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

Basal cell adenocarcinoma. **Explanation:** The grading of salivary gland malignancies is a high-yield topic for NEET-PG, as it determines both prognosis and surgical management. **1. Why Basal Cell Adenocarcinoma is the Correct Answer:** Basal cell adenocarcinoma is considered a **low-grade** malignancy. While it is the malignant counterpart of basal cell adenoma, it is characterized by an indolent clinical course, slow growth, and a low rate of distant metastasis (approx. 10%). It is locally invasive but lacks the aggressive features seen in high-grade tumors. **2. Analysis of Incorrect Options (High-Grade Malignancies):** * **Salivary Duct Carcinoma:** This is one of the most aggressive salivary gland cancers. It histologically resembles high-grade mammary ductal carcinoma and carries a very poor prognosis. * **Adenoid Cystic Carcinoma:** While slow-growing, it is classified as high-grade due to its relentless nature, high rate of **perineural invasion**, and frequent late distant metastases (often to the lungs). [1] * **Mucoepidermoid Carcinoma:** This tumor can be low, intermediate, or high-grade. [1] However, in the context of this question, it is a classic example of a tumor that frequently presents in a high-grade form (especially when the epidermoid component predominates). **3. NEET-PG High-Yield Pearls:** * **Most common salivary gland tumor:** Pleomorphic Adenoma (Benign). * **Most common salivary gland malignancy:** Mucoepidermoid Carcinoma. * **Tumor with highest propensity for perineural invasion:** Adenoid Cystic Carcinoma (Cribriform "Swiss-cheese" pattern). [1] * **Hot Spot:** Warthin’s Tumor (Adenolymphoma) is associated with smoking and is typically "hot" on Technetium-99m pertechnetate scans. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Head and Neck, pp. 753-755.

Q: A Mallory-Weiss tear occurs at which anatomical location?

Gastro-oesophageal junction. **Explanation:** **Mallory-Weiss Syndrome** refers to longitudinal mucosal lacerations at the **gastro-oesophageal (GE) junction** or the proximal gastric mucosa. These tears are classically caused by a sudden, sharp increase in intra-abdominal pressure, typically due to forceful retching or vomiting (often associated with acute alcohol intoxication or eating disorders). * **Why Option A is correct:** The GE junction is the point of maximum mechanical stress during the retrograde propulsion of gastric contents against a closed or poorly coordinated sphincter. The sudden distension causes the mucosa to tear, leading to hematemesis (vomiting of blood). * **Why Options B, C, and D are incorrect:** These junctions (Duodeno-jejunal, Ileo-caecal, and Colo-rectal) are not physiological sites of high-pressure stress during vomiting. They are involved in different pathologies, such as the Ligament of Treitz (B), Crohn’s disease or intussusception (C), and malignancy or hemorrhoids (D). **High-Yield Clinical Pearls for NEET-PG:** 1. **Clinical Presentation:** Typically presents as **painful hematemesis** following an episode of non-bloody vomiting (distinguish from Boerhaave Syndrome, which involves transmural rupture and excruciating retrosternal pain). 2. **Risk Factors:** Chronic alcoholism (most common) and Hiatal hernia (present in ~75% of cases as it increases the pressure gradient). 3. **Diagnosis:** Upper GI Endoscopy is the gold standard, showing linear mucosal tears crossing the GE junction. 4. **Prognosis:** Most tears are superficial and heal spontaneously without surgical intervention.

Question 1

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

Accepted Answer

CD 117

Answer

CD 34

Answer

CD 30

Answer

CD 10

Question 2

What is the most common site of squamous cell carcinoma of the esophagus?

Accepted Answer

Middle third

Answer

Upper third

Answer

Lower third

Answer

Cardia

Question 3

What is the commonest variety of carcinoma of the stomach?

Accepted Answer

Adenocarcinoma

Answer

Squamous cell carcinoma

Answer

Colloid carcinoma

Answer

None of the above

Question 4

A 54-year-old woman presents with complaints of abdominal fullness and early satiety. She denies a change in bowel habits and states that constipation is her normal state. A radiographic bowel series shows an 'apple core' lesion in her sigmoid colon. Which of the following markers is expected to be elevated in this patient?

Accepted Answer

Carcinoembryonic antigen (CEA)

Answer

Alpha-fetoprotein (AFP)

Answer

Human chorionic gonadotropin (hCG)

Answer

Lactate dehydrogenase (LDH)

Question 5

Toxic megacolon is seen as a complication in which of the following conditions?

Accepted Answer

Ulcerative colitis

Answer

Crohn's disease

Answer

Colonic diverticulosis

Answer

Miliary TB

Question 6

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

Accepted Answer

Basal cell adenocarcinoma

Answer

Mucoepidermoid carcinoma

Answer

Adenoid cystic carcinoma

Answer

Salivary duct carcinoma

Question 7

Helicobacter pylori infection is associated with which type of gastritis?

Accepted Answer

Type B Gastritis

Answer

Type A Gastritis

Answer

Autoimmune Gastritis

Answer

Allergic Gastritis

Question 8

What is the most common extranodal site for non-Hodgkin's lymphoma?

Accepted Answer

Stomach

Answer

Brain

Answer

Intestines

Answer

Tonsils

Question 9

A Mallory-Weiss tear occurs at which anatomical location?

Accepted Answer

Gastro-oesophageal junction

Answer

Duodeno-jejunal flexure

Answer

Ileo-caecal junction

Answer

Colo-rectal junction

Question 10

A 68-year-old man has had "heartburn" and substernal pain after meals for 25 years. For the past year, he has had increased pain with difficulty swallowing both liquids and solids. On physical examination, there are no remarkable findings. Upper gastrointestinal endoscopy shows an ulcerated lower esophageal mass that nearly occludes the lumen of the esophagus. A biopsy specimen of this mass is most likely to show which of the following neoplasms?

Accepted Answer

Adenocarcinoma

Answer

Carcinoid tumor

Answer

Leiomyosarcoma

Answer

Non-Hodgkin lymphoma

Gastrointestinal Pathology — MCQs

Gastrointestinal Pathology — MCQs

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