Gastrointestinal Pathology Practice Questions

Q: The highest malignant potential is seen in which of the following conditions?

Familial polyposis. **Explanation:** The correct answer is **Familial Adenomatous Polyposis (FAP)** because it carries a **100% lifetime risk** of developing colorectal carcinoma if left untreated. ### Why Familial Polyposis is Correct: FAP is an autosomal dominant condition caused by a mutation in the **APC gene** on chromosome 5q21. It is characterized by the development of hundreds to thousands of adenomatous polyps throughout the colon. Due to the sheer number of polyps and the "adenoma-carcinoma sequence," malignancy is an absolute certainty, typically occurring by the age of 40. Prophylactic proctocolectomy is the standard management. ### Why Other Options are Incorrect: * **Ulcerative Colitis (UC):** While UC significantly increases the risk of colorectal cancer (approx. 7-10% after 20 years of pancolitis), the risk is not absolute (100%) like in FAP. * **Crohn’s Disease:** There is an increased risk of adenocarcinoma in the small bowel and colon, but this risk is lower than that seen in Ulcerative Colitis and significantly lower than in FAP. * **Infantile (Juvenile) Polyp:** Solitary juvenile polyps are hamartomatous and have **no malignant potential**. However, "Juvenile Polyposis Syndrome" (multiple polyps) does carry a risk, but it is still lower than FAP. ### NEET-PG High-Yield Pearls: * **Gardner Syndrome:** FAP + Osteomas (mandible) + Soft tissue tumors (Desmoid tumors) + Sebaceous cysts. * **Turcot Syndrome:** FAP + CNS tumors (Medulloblastoma). * **Screening for FAP:** Starts at age 10–12 years with annual sigmoidoscopy. * **CHRPE:** Congenital Hypertrophy of Retinal Pigment Epithelium is the earliest extra-colonic manifestation of FAP.

Q: A cyst arising from an unerupted tooth is classified as which of the following?

Dentigerous cyst. **Explanation:** A **Dentigerous cyst** (also known as a follicular cyst) is the most common type of developmental odontogenic cyst [1]. It originates from the **reduced enamel epithelium** of the dental follicle and characteristically surrounds the crown of an **unerupted or impacted tooth**. Radiographically, it appears as a well-defined unilocular radiolucency attached to the cemento-enamel junction (CEJ). The most common site is the mandibular third molar. **Analysis of Incorrect Options:** * **Odontogenic Keratocyst (OKC):** Arises from the dental lamina. While it can be associated with unerupted teeth, it is defined by its unique histology (parakeratinized lining) and aggressive behavior rather than its association with an unerupted crown. * **Radicular Cyst:** This is an inflammatory cyst, not developmental. It arises from the **rests of Malassez** and is typically found at the apex of a **non-vital (carious) tooth** [1]. * **Gorlin Cyst (Calcifying Odontogenic Cyst):** A rare developmental lesion characterized by "ghost cells" and calcifications. While it can be associated with unerupted teeth, it is not the primary classification for a cyst arising specifically from the follicle of an unerupted tooth. **High-Yield Pearls for NEET-PG:** * **Most common developmental odontogenic cyst:** Dentigerous cyst [1]. * **Most common inflammatory odontogenic cyst:** Radicular cyst. * **Key Histology:** Dentigerous cysts are lined by thin, non-keratinized stratified squamous epithelium. * **Complications:** If left untreated, a dentigerous cyst can transform into an Ameloblastoma or Squamous Cell Carcinoma. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Head and Neck, pp. 741-742.

Q: A patient is being investigated for chronic diarrhoea. Small intestinal mucosal biopsy shows PAS positive foamy macrophages. What is the probable diagnosis?

Whipple disease. **Explanation:** The presence of **PAS-positive foamy macrophages** in the lamina propria of the small intestine is the classic histopathological hallmark of **Whipple disease** [1]. This multisystemic illness is caused by the gram-positive bacterium *Tropheryma whipplei*. The PAS (Periodic Acid-Schiff) stain highlights the glycoprotein-rich cell walls of the partially digested bacteria within the lysosomes of macrophages. **Why the other options are incorrect:** * **Chronic amoebiasis:** Typically involves the colon (large intestine), not the small intestine [2]. Histology would show flask-shaped ulcers and trophozoites of *Entamoeba histolytica*, often containing ingested RBCs (erythrophagocytosis). * **Chronic giardiasis:** *Giardia lamblia* is an intraluminal parasite that attaches to the brush border. Diagnosis is made by identifying pear-shaped trophozoites in stool or duodenal aspirates; it does not cause PAS-positive macrophage infiltration. * **Intestinal sarcoidosis:** This is characterized by **non-caseating granulomas**, not foamy macrophages. While sarcoidosis can affect the GI tract, it is extremely rare compared to other manifestations. **High-Yield Clinical Pearls for NEET-PG:** * **Clinical Triad:** Diarrhea/Malabsorption, Weight loss, and Migratory large-joint Arthralgia [1]. * **Rule Out:** Always differentiate from *Mycobacterium avium-intracellulare* (MAI) infection in HIV patients, which also shows PAS-positive macrophages. However, MAI is **Acid-Fast Bacillus (AFB) positive**, whereas *T. whipplei* is **AFB negative**. * **Treatment:** Long-term antibiotics are required (usually Ceftriaxone followed by oral Trimethoprim-sulfamethoxazole for 1 year). * **Electron Microscopy:** Shows characteristic "trilaminar" cell wall organisms.

Q: Cobble stoning of the intestine with the string sign of Twort is seen in which condition?

Crohn's disease. **Explanation:** **Crohn’s Disease (Correct Answer):** Crohn’s disease is a chronic, transmural inflammatory bowel disease that can affect any part of the GIT [1]. The **"Cobblestone appearance"** occurs due to deep, longitudinal, and transverse linear ulcers (fissures) intersecting with islands of edematous, intact mucosa [1]. The **"String sign of Kantor"** (often referred to in radiology/pathology contexts alongside the String sign of Twort) represents a terminal ileum that has become significantly narrowed due to transmural inflammation, edema, and subsequent fibrosis/cicatrization, appearing as a thin thread of contrast on imaging [1]. **Why other options are incorrect:** * **Ulcerative Colitis:** Characterized by superficial mucosal involvement, continuous lesions (starting from the rectum), and "Pseudopolyps." It lacks transmural fibrosis, so the "string sign" is absent. Lead-pipe appearance is the classic radiological finding. * **Ischemic Colitis:** Typically presents with "Thumbprinting" on imaging due to submucosal hemorrhage and edema, usually at splenic flexure (Griffith’s point). * **Amoebic Colitis:** Characterized by "Flask-shaped ulcers" with narrow necks and broad bases, primarily involving the cecum and ascending colon. **NEET-PG High-Yield Pearls:** * **Transmural inflammation** is the hallmark of Crohn’s (leads to fistulas and strictures) [1]. * **Non-caseating granulomas** are pathognomonic (seen in ~40-60% of cases) [1]. * **Creeping fat:** Mesenteric fat wraps around the serosal surface of the bowel. * **Skip lesions:** Areas of disease separated by normal-appearing "skip" segments [1]. * **ASCA (Anti-Saccharomyces cerevisiae antibodies)** is positive in Crohn’s, whereas **p-ANCA** is associated with Ulcerative Colitis. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Alimentary System Disease, pp. 365-367.

Q: Multiple cutaneous sebaceous adenomas are seen in which of the following conditions?

Muir-Torre syndrome. ### Explanation **Muir-Torre syndrome** is a phenotypic variant of **Lynch syndrome** (Hereditary Non-Polyposis Colorectal Cancer - HNPCC). It is characterized by the association of at least one **sebaceous gland tumor** (sebaceous adenoma, sebaceous carcinoma, or sebaceous epithelioma) and at least one internal malignancy (most commonly colorectal or genitourinary cancers) [1]. The underlying pathophysiology involves germline mutations in **DNA mismatch repair (MMR) genes**, most frequently **MSH2** (90%) and MLH1 [1]. #### Analysis of Options: * **Gardner’s Syndrome (Option A):** A variant of Familial Adenomatous Polyposis (FAP) characterized by intestinal polyps plus extraintestinal manifestations like **osteomas** (mandible), **epidermoid cysts**, and **desmoid tumors**. It is not typically associated with sebaceous adenomas. * **Turcot’s Syndrome (Option B):** Characterized by the association of intestinal polyposis with **Central Nervous System (CNS) tumors**. Specifically, FAP with Medulloblastoma or Lynch syndrome with Glioblastoma multiforme. * **Cowden Syndrome (Option C):** Part of the PTEN hamartoma tumor syndrome. It presents with multiple **trichilemmomas** (hair follicle tumors), oral papillomas, and an increased risk of breast, thyroid, and endometrial cancers. #### NEET-PG High-Yield Pearls: * **Muir-Torre Syndrome:** Think "Sebaceous tumors + Internal malignancy + MSH2 mutation." * **Sebaceous Adenoma:** This is the most specific cutaneous marker for Muir-Torre syndrome. * **Microsatellite Instability (MSI):** These patients exhibit MSI due to defective MMR genes [1]. * **Screening:** Patients presenting with a sebaceous adenoma should be screened for internal malignancies via colonoscopy and imaging. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, p. 817.

Question 1

The highest malignant potential is seen in which of the following conditions?

Accepted Answer

Familial polyposis

Answer

Crohn's disease

Answer

Ulcerative colitis

Answer

Infantile polyp

Question 2

A cyst arising from an unerupted tooth is classified as which of the following?

Accepted Answer

Dentigerous cyst

Answer

Odontogenic keratocyst

Answer

Radicular cyst

Answer

Gorlin cyst

Question 3

A patient is being investigated for chronic diarrhoea. Small intestinal mucosal biopsy shows PAS positive foamy macrophages. What is the probable diagnosis?

Accepted Answer

Whipple disease

Answer

Chronic amoebiasis

Answer

Chronic giardiasis

Answer

Intestinal sarcoidosis

Question 4

Which gene is associated with familial adenomatous polyposis?

Accepted Answer

APC

Answer

p53

Answer

Rb

Answer

RET

Question 5

Cobble stoning of the intestine with the string sign of Twort is seen in which condition?

Accepted Answer

Crohn's disease

Answer

Ulcerative colitis

Answer

Ischemic colitis

Answer

Amoebic colitis

Question 6

All of the following are inherited in an autosomal dominant pattern EXCEPT?

Accepted Answer

Cronkhite-Canada syndrome

Answer

Bannayan-Riley-Ruvalcaba syndrome

Answer

Peutz-Jeghers syndrome

Answer

Gardner's syndrome

Question 7

A 65-year-old male with a history of smoking and alcohol abuse complains of poor appetite and difficulty swallowing both solid and liquid foods over the course of the last 4 months. He has lost 10 kg and occasionally vomits blood. A mass is detected in his esophagus and is subsequently biopsied. What is the most likely histological appearance of the biopsy?

Accepted Answer

Squamous cell morphology

Answer

Glandular epithelium associated with desmoplasia

Answer

Malignant tumor of mesenchymal origin

Answer

Tumor derived from all three germ layers

Question 8

The best prognosis in carcinoma of the stomach is associated with which type?

Accepted Answer

Superficial spreading type

Answer

Ulcerative type

Answer

Linitis plastica type

Answer

Polypoidal type

Question 9

Colon carcinoma is associated with all the following except:

Accepted Answer

Rb

Answer

Mismatch repair genes

Answer

APC

Answer

b-catenin

Question 10

Multiple cutaneous sebaceous adenomas are seen in which of the following conditions?

Accepted Answer

Muir-Torre syndrome

Answer

Gardner's syndrome

Answer

Turcott's syndrome

Answer

Cowden syndrome

Gastrointestinal Pathology — MCQs

Gastrointestinal Pathology — MCQs

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