Gastrointestinal Pathology Practice Questions

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.

Q: Pleomorphic adenoma arises from which type of cell?

Myoepithelial cells. **Explanation:** **Pleomorphic Adenoma (Mixed Tumor)** is the most common benign tumor of the salivary glands, most frequently involving the parotid gland. 1. **Why Myoepithelial cells are correct:** The term "pleomorphic" refers to the tumor's architectural diversity. It is derived from a dual proliferation of both **epithelial and myoepithelial cells** (which are of ectodermal origin) within a mesenchyme-like stroma. The myoepithelial cells are the "drivers" of this tumor; they are responsible for secreting the characteristic stromal components (myxoid, chondroid, or osteoid material), giving it the "mixed" appearance. 2. **Why other options are incorrect:** * **Acinar cells:** These are the functional secretory cells of the salivary gland. While they can be involved in tumors like Acinic Cell Carcinoma, they are not the primary cell of origin for pleomorphic adenoma. * **Connective tissue:** Although the tumor contains a "mesenchymal-like" stroma (chondroid/myxoid), this is a result of metaplasia from myoepithelial cells, not a primary origin from native connective tissue. * **Stem cells:** While all tumors technically arise from undifferentiated cells, the specific diagnostic cellular lineage for pleomorphic adenoma is the myoepithelial cell. **High-Yield NEET-PG Pearls:** * **Most common site:** Superficial lobe of the Parotid gland. * **Clinical presentation:** Slow-growing, painless, firm, mobile mass ("Mobile parotid swelling"). * **Histology:** Characterized by "islands of epithelium in a sea of chondromyxoid stroma." * **Risk of Malignancy:** 3–5% can transform into **Carcinoma ex-pleomorphic adenoma** (suspect if there is sudden rapid growth or facial nerve palsy). * **Treatment:** Superficial parotidectomy (Enucleation is avoided due to high recurrence rates from pseudopod extensions through the capsule).

Q: Entero-enteric fistula is found in all EXCEPT:

Ulcerative colitis. **Explanation:** The core concept differentiating these conditions is the **depth of bowel wall involvement**. **Why Ulcerative Colitis (UC) is the correct answer:** Ulcerative colitis is primarily a **mucosal and submucosal disease**. It does not involve the full thickness of the bowel wall (transmural). Since fistula formation requires a transmural inflammatory process that breaches the serosa to adhere to and penetrate an adjacent loop of bowel, UC typically does not present with entero-enteric or any other types of fistulae. **Why the other options are incorrect:** * **Crohn’s Disease:** This is a **transmural** inflammatory condition. Deep fissuring ulcers (aphthous ulcers) penetrate through the serosa, leading to adhesions and fistula formation (entero-enteric, entero-vesical, or entero-cutaneous). This is a hallmark complication of Crohn’s. * **Colo-rectal Malignancy:** Advanced tumors can invade through the bowel wall into adjacent structures. Necrosis at the center of a locally invasive tumor can create a communication (fistula) between two loops of bowel. * **Actinomycosis:** Caused by *Actinomyces israelii*, this infection is known for causing "woody" induration and **multiple discharging sinuses/fistulae** that cross tissue planes, often involving the ileocecal region. **NEET-PG High-Yield Pearls:** * **Crohn’s vs. UC:** Crohn’s = Transmural (Fistulae common); UC = Mucosal (Fistulae rare). * **Toxic Megacolon:** While fistulae are rare in UC, toxic megacolon is a life-threatening complication seen more frequently in UC than in Crohn’s. * **Most common site for Crohn’s fistula:** Entero-enteric (between two loops of small bowel). * **Actinomycosis:** Look for "Sulfur granules" in the discharge and a history of dental procedures or appendicitis.

Question 1

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 2

Which of the following is associated with H.pylori?

Accepted Answer

MALToma

Answer

Ulcerative colitis

Answer

Crohn disease

Answer

Celiac sprue

Question 3

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 4

The recurrence of pleomorphic adenoma is attributed to which of the following factors?

Accepted Answer

Presence of an incomplete capsule

Answer

Mixed origin

Answer

Absence of capsule

Answer

Perineural spread

Question 5

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 6

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 7

Increased urine levels of 5-HIAA are associated with which condition?

Accepted Answer

Carcinoid tumor

Answer

Liver Cirrhosis

Answer

Papillary carcinoma of the Thyroid

Answer

Small cell carcinoma of the lung

Question 8

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 9

Pleomorphic adenoma arises from which type of cell?

Accepted Answer

Myoepithelial cells

Answer

Acinar cells

Answer

Connective tissue

Answer

Stem cells

Question 10

Entero-enteric fistula is found in all EXCEPT:

Accepted Answer

Ulcerative colitis

Answer

Crohn's disease

Answer

Colo-rectal malignancy

Answer

Actinomycosis

Gastrointestinal Pathology — MCQs

Gastrointestinal Pathology — MCQs

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