Gastrointestinal Pathology Practice Questions

Q: A 40-year-old man is diagnosed with a gastrointestinal stromal tumor (GIST). Which marker is most useful for confirming the diagnosis?

CD117. ***CD117*** - **CD117** (also known as c-Kit) is a transmembrane receptor tyrosine kinase found in over 95% of **Gastrointestinal Stromal Tumors (GISTs)** [1]. - Its expression is crucial for confirming the diagnosis of GISTs and also guides targeted therapy with **tyrosine kinase inhibitors** like imatinib [1]. *CD34* - **CD34** is a marker expressed in about 70-80% of GISTs, but it is less specific than CD117. - It is also found in other tumors like **solitary fibrous tumors** and some vascular tumors, making it less definitive for GIST diagnosis on its own. *Chromogranin* - **Chromogranin** is a marker for **neuroendocrine tumors** (e.g., carcinoids, pheochromocytomas). - GISTs are mesenchymally derived and do not typically express neuroendocrine markers. *S100* - **S100 protein** is a marker for neural crest-derived tumors, particularly **melanomas** and **schwannomas**. - While some rare GISTs can show aberrant S100 positivity, it is not a primary or characteristic marker for GISTs. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 782-783.

Q: A 60-year-old male patient presents with abdominal pain and changes in bowel habits. Colonoscopy reveals a flat, erythematous lesion. Which colorectal precursor lesion is commonly associated with microsatellite instability?

Sessile serrated adenoma. ***Sessile serrated adenoma*** - **Sessile serrated adenomas (SSAs)** are often found in the right colon and are characterized by a **microsatellite instability (MSI)** pathway, leading to colorectal cancer. - They progress via the **serrated pathway** involving CpG island methylator phenotype (CIMP) and often harbor **BRAF mutations**, resulting in **MSI-high** cancers. - Their flat, erythematous appearance on colonoscopy can be subtle, making them challenging to detect, but they are significant precursors to MSI-high cancers. *Tubular adenoma* - **Tubular adenomas** are the most common type of sporadic colorectal polyp, typically progressing to cancer via the **adenoma-carcinoma sequence** (chromosomal instability pathway). - They follow the traditional pathway involving **APC, KRAS, and p53 mutations**, not the **microsatellite instability (MSI)** pathway. *Villous adenoma* - **Villous adenomas** are characterized by their velvety or frond-like appearance and a higher risk of malignant transformation compared to tubular adenomas. - They mainly progress through the traditional **adenoma-carcinoma sequence** with **chromosomal instability (CIN)**, not **microsatellite instability (MSI)**. *Hyperplastic polyp* - **Hyperplastic polyps** are generally considered benign and have a very low malignant potential, especially small ones found in the distal colon. - While large or proximal hyperplastic polyps may rarely be associated with the **serrated pathway**, they lack the dysplastic features of sessile serrated adenomas and are not primarily linked to **MSI-high** cancers.

Q: Identify the primary immune response triggered by the presence of Helicobacter pylori in the gastric mucosa.

Induction of mucosal inflammation. ***Induction of mucosal inflammation*** - The presence of *H. pylori* in the gastric mucosa directly triggers a robust **inflammatory response**, characterized by the infiltration of neutrophils, macrophages, and lymphocytes. - This **chronic inflammation** is the primary immune response and a key factor in the pathogenesis of *H. pylori*-associated diseases like gastritis, peptic ulcers, and gastric cancer. *Activation of complement system* - While complement activation can occur as part of the immune response, it is not the *primary* and most significant immediate response triggered by *H. pylori* in the mucosa. - *H. pylori* has evolved mechanisms to evade and resist complement-mediated killing, making it less effective as a primary defense. *Cytotoxic T cell activity* - **Cytotoxic T cells (CD8+)** are primarily involved in targeting and destroying virally infected cells or cancer cells, not typically extracellular bacterial pathogens like *H. pylori*. - While some T cell activity contributes to the overall immune response, it's not the initial or primary mechanism for directly combating *H. pylori* in the mucosa. *Antibody production* - **Antibody production** (humoral immunity) develops as a later, adaptive immune response to *H. pylori* infection. - While important for long-term immunity and diagnostics (e.g., serology), it is not the *primary* immediate immune response triggered upon initial detection in the gastric mucosa.

Q: Identify the condition shown in the image.

Juvenile polyp. ***Juvenile polyp*** - Typically presents in children and is characterized by a **pedunculated appearance** in the colon, often asymptomatic but can cause **rectal bleeding** [2]. - These polyps are usually **benign** and represent a common type of gastrointestinal polyp seen in the pediatric population [2]. *Hyperplastic polyp* - Generally found in adults and characterized by **crypt fission** and **serrated architecture**, presenting as a flat lesion. - Hyperplastic polyps are considered **non-neoplastic** and are not inherently related to cancer risk. *Villous adenoma* - These are **malignant potential** lesions [1][3], characterized by a **frond-like appearance** and can cause significant symptoms like rectal bleeding and obstructive symptoms [1]. - Unlike juvenile polyps, they often occur in older adults and have a **higher risk for colorectal cancer** [1][3]. *Peutz Jeghers* - Associated with **hamartomatous polyps** and characteristic **mucocutaneous pigmentation**, typically involves multiple polyps in the gastrointestinal tract [2]. - This condition has a hereditary component and carries a **hereditary cancer risk**, which is not the case with juvenile polyps [2]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Alimentary System Disease, pp. 371-372. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, p. 813. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 815-817.

Q: The histopathological image shows a section of colon. What histological feature seen in the image is more characteristic of Ulcerative Colitis than Crohn's Disease?

Presence of crypt abscesses. ***Crypt abscess*** - **Crypt abscesses** are a hallmark of ulcerative colitis, where there is **inflammation and necrosis** within the intestinal crypts [1]. - This feature is distinct from Crohn's disease, which does not typically present with crypt abscesses but rather with **transmural inflammation** [2,3]. *Diffuse distribution of pseudopolyps* - While pseudopolyps can occur in ulcerative colitis, they are not a **distinct histological feature** that differentiates it from Crohn's. - Pseudopolyps are **proliferative tissue islands** due to mucosal regeneration, and their presence is not exclusive to either condition. *Mucosal edema* - Mucosal edema is a common feature in various forms of colitis but is **not specific** to differentiate ulcerative colitis from Crohn's disease. - Both conditions can exhibit **mucosal edema**, making it insufficient for definitive diagnosis. *Lymphoid aggregates in the mucosa* - Lymphoid aggregates can be found in Crohn's disease, particularly in the **intestinal lymphoid tissue** [2], but they are **not a defining feature** of ulcerative colitis. - Ulcerative colitis primarily involves **continuous mucosal inflammation** without these prominent aggregates [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, p. 809. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Alimentary System Disease, pp. 365-368. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 806-807.

Q: Positive periodic acid-Schiff (PAS) macrophages are seen in which of the following conditions?

Whipple's disease. ***Whipple's disease*** - **Whipple's disease** is caused by the bacterium *Tropheryma whipplei*, which is ingested by macrophages and accumulates in their lysosomes [1]. - The bacterial cell wall contains **glycoproteins** and **proteoglycans** that stain magenta (red-purple) with the **periodic acid-Schiff (PAS)** stain. - PAS-positive, diastase-resistant macrophages in the lamina propria of the small intestine are **pathognomonic** for Whipple's disease [1]. *Crohn's disease* - Crohn's disease is an **inflammatory bowel disease** characterized by transmural inflammation and non-caseating granulomas. - While it involves macrophages in the inflammatory process, they do not typically show **PAS-positive inclusions**. *HIV/AIDS* - HIV/AIDS is a **viral infection** that primarily targets CD4+ T lymphocytes and macrophages. - Although macrophages are involved in HIV infection and can be found in intestinal tissue, they do not exhibit **PAS-positive inclusions** characteristic of Whipple's disease. *Celiac disease* - Celiac disease is an **autoimmune enteropathy** triggered by gluten, causing villous atrophy and malabsorption. - The histology shows increased intraepithelial lymphocytes and crypt hyperplasia, but **macrophages are not PAS-positive**. - Both Whipple's and celiac disease can present with malabsorption, making clinical differentiation important [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 798-799.

Q: Which of the following is not a typical feature of Crohn's disease?

Crypt Abscess. ***Lymphoid hyperplasia*** - Lymphoid hyperplasia is **not a characteristic** feature of Crohn's disease; rather, it is more common in conditions like **ulcerative colitis** [1]. - Crohn's disease typically shows **granulomatous inflammation** and segmental involvement, rather than lymphoid tissue proliferation [1]. *Crypt Abscess* - Crypt abscesses are often found in **inflammatory bowel diseases**, including Crohn's disease, indicating **active mucosal inflammation**. - They are a hallmark finding in Crohn's and indicate the presence of **neutrophils** in the crypts of the intestinal lining. *Transmural involvement* - Transmural involvement is characteristic of Crohn's disease [1][2], leading to complications like **strictures** and **fistulas**. - This distinguishes it from ulcerative colitis, which primarily affects the **mucosal layer** [1]. *Skin lesion* - While skin lesions can occur in Crohn's disease, they are **not a defining feature**; they are more associated with extra-intestinal manifestations [2]. - Common presentations may include **erythema nodosum**, but these are secondary to the main gastrointestinal pathology. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Alimentary System Disease, pp. 365-367. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 806-807.

Q: Which of the following statements about small intestinal tumors is true?

Carcinoids are more common in the ileum.. ***Carcinoids are more common in the ileum.*** - **Carcinoid tumors**, which are neuroendocrine tumors, are the most common primary malignant tumors of the small intestine, and their highest incidence is found in the **ileum**. - They often arise from enterochromaffin cells in the submucosa and can secrete vasoactive substances, leading to **carcinoid syndrome**. *Adenocarcinomas are the most common small intestinal tumors.* - While adenocarcinomas occur in the small intestine, they are not the most common type; **carcinoids** are more prevalent. - Small intestinal adenocarcinomas are typically found in the **duodenum**, unlike carcinoids which favor the ileum. *Adenomatous polyps are the most common small intestinal tumors.* - **Adenomatous polyps** are benign growths but are not the most common small intestinal tumors; **carcinoids** hold this distinction. - Though rare, they can undergo malignant transformation, particularly when associated with genetic syndromes like **Familial Adenomatous Polyposis (FAP)**. *The risk of developing small bowel tumors correlates positively with colorectal cancer.* - There is generally **no strong positive correlation** between the risk of developing typical small bowel tumors and colorectal cancer in the general population, although some genetic syndromes like **FAP** increase risks for both. - The etiologies and predominant tumor types for small bowel and colorectal cancers are largely distinct.

Q: Gene associated with the development of Peutz-Jeghers syndrome is?

STK11. ***STK11*** - **Peutz-Jeghers syndrome (PJS)** is an autosomal dominant disorder caused by a germline mutation in the **STK11 (serine/threonine kinase 11)** gene. - The STK11 gene acts as a **tumor suppressor**, and its inactivation leads to the characteristic hamartomatous polyps and increased cancer risk seen in PJS [1]. *PTEN* - Mutations in the **PTEN gene** are associated with **Cowden syndrome**, another hereditary polyposis syndrome. - Cowden syndrome is characterized by hamartomatous polyps, mucocutaneous lesions, and an increased risk of breast, thyroid, and endometrial cancers. *KRAS* - The **KRAS gene** is a proto-oncogene frequently mutated in various cancers, including colorectal cancer, but it is not directly associated with the primary genetic defect of Peutz-Jeghers syndrome. - **KRAS mutations** are often found in sporadic colorectal cancers and can influence response to certain therapies. *BRCA 1* - The **BRCA1 gene** is a well-known tumor suppressor gene primarily associated with an increased risk of hereditary breast and ovarian cancers. - It plays a crucial role in DNA repair and is not directly involved in the pathogenesis of Peutz-Jeghers syndrome.

Q: Which of the following morphological features is most characteristic for distinguishing ulcerative colitis from Crohn's disease?

Diffuse distribution of pseudopolyps. ***Diffuse distributions of pseudopolyps*** - ***Ulcerative colitis*** is characterized by the presence of **pseudopolyps**, which are formed due to mucosal regeneration and are distributed diffusely throughout the affected areas [2][3]. - The presence and distribution of **pseudopolyps** are specifically associated with **mucosal inflammation** in ulcerative colitis, helping distinguish it from Crohn's disease [2]. *Crypt abscesses* - Crypt abscesses are often seen in **both ulcerative colitis** and Crohn's disease but are more prominent in ulcerative colitis [1][2]. - They do not distinctly distinguish between the two conditions, as both can show this histological feature [2]. *Mucosal edema* - Mucosal edema can occur in both ulcerative colitis and Crohn's disease during active inflammation [2]. - It's a nonspecific sign and lacks the diagnostic specificity needed to differentiate the two diseases [2]. *Lymphoid aggregates in the mucosa* - Lymphoid aggregates may be found in Crohn's disease and, to a lesser degree, in ulcerative colitis, but are not unique to either condition [2][4]. - This feature is seen variably in both diseases and fails to serve as a distinguishing morphological trait [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, p. 809. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Alimentary System Disease, pp. 365-366. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Alimentary System Disease, pp. 367-368. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 806-807.

Question 1

A 40-year-old man is diagnosed with a gastrointestinal stromal tumor (GIST). Which marker is most useful for confirming the diagnosis?

Accepted Answer

CD117

Answer

CD34

Answer

Chromogranin

Answer

S100

Question 2

A 60-year-old male patient presents with abdominal pain and changes in bowel habits. Colonoscopy reveals a flat, erythematous lesion. Which colorectal precursor lesion is commonly associated with microsatellite instability?

Accepted Answer

Sessile serrated adenoma

Answer

Tubular adenoma

Answer

Villous adenoma

Answer

Hyperplastic polyp

Question 3

Identify the primary immune response triggered by the presence of Helicobacter pylori in the gastric mucosa.

Accepted Answer

Induction of mucosal inflammation

Answer

Activation of complement system

Answer

Cytotoxic T cell activity

Answer

Antibody production

Question 4

Identify the condition shown in the image.

Accepted Answer

Juvenile polyp

Answer

Peutz-Jeghers

Answer

Villous adenoma

Answer

Hyperplastic polyp

Question 5

The histopathological image shows a section of colon. What histological feature seen in the image is more characteristic of Ulcerative Colitis than Crohn's Disease?

Accepted Answer

Presence of crypt abscesses

Answer

Presence of pseudopolyps

Answer

Mucosal edema present

Answer

Lymphoid aggregates in the mucosa present

Question 6

Positive periodic acid-Schiff (PAS) macrophages are seen in which of the following conditions?

Accepted Answer

Whipple's disease

Answer

Crohn's disease

Answer

HIV/AIDS

Answer

Celiac disease

Question 7

Which of the following is not a typical feature of Crohn's disease?

Accepted Answer

Crypt Abscess

Answer

Skin lesion

Answer

Transmural involvement

Answer

Lymphoid hyperplasia

Question 8

Which of the following statements about small intestinal tumors is true?

Accepted Answer

Carcinoids are more common in the ileum.

Answer

The risk of developing small bowel tumors correlates positively with colorectal cancer.

Answer

Adenomatous polyps are the most common small intestinal tumors.

Answer

Adenocarcinomas are the most common small intestinal tumors.

Question 9

Gene associated with the development of Peutz-Jeghers syndrome is?

Accepted Answer

STK11

Answer

PTEN

Answer

KRAS

Answer

BRCA 1

Question 10

Which of the following morphological features is most characteristic for distinguishing ulcerative colitis from Crohn's disease?

Accepted Answer

Diffuse distribution of pseudopolyps

Answer

Lymphoid aggregates in the mucosa

Answer

Crypt abscesses

Answer

Mucosal edema

Gastrointestinal Pathology — MCQs

Gastrointestinal Pathology — MCQs

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