NEET-PG 2013 - Pathology Practice Questions

Q: Macrophages are converted to epithelioid cells by which cytokine?

IFN-γ. ***IFN-γ: A cytokine involved in classical macrophage activation*** - **Interferon-gamma (IFN-γ)** is a key cytokine produced by activated T cells and NK cells that plays a crucial role in activating macrophages and converting them into **epithelioid cells** [1]. - This conversion is essential for the formation of **granulomas**, a hallmark of chronic inflammatory responses, particularly in infections like tuberculosis [1]. *TNF-α: A cytokine involved in granuloma maintenance* - **Tumor Necrosis Factor-alpha (TNF-α)** is vital for the **formation and maintenance** of granulomas, but it is not directly responsible for the initial conversion of macrophages to epithelioid cells. - While TNF-α helps to **organize and contain** the infection within the granuloma, IFN-γ drives the phenotypic change of macrophages. *TGF-β: A cytokine involved in tissue remodeling* - **Transforming Growth Factor-beta (TGF-β)** is predominantly involved in **tissue repair, fibrosis, and immune regulation**, promoting extracellular matrix production. - It does not primarily induce the differentiation of macrophages into epithelioid cells; rather, it often plays a role in the later stages of granuloma development, contributing to **fibrotic encapsulation** [1]. *IL-4: A cytokine involved in alternative macrophage activation* - **Interleukin-4 (IL-4)** is a characteristic cytokine that drives **alternative macrophage activation (M2 pathway)**, leading to roles in allergic responses and tissue repair [1]. - The M2 phenotype is distinct from the classically activated (M1) phenotype associated with epithelioid cell formation, which is driven by IFN-γ. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, p. 109.

Q: Which mediators are involved in the resolution of inflammation?

Resolvins, protectins, and lipoxins. ***Resolvins, protectins, and lipoxins*** - These are **specialized pro-resolving mediators (SPMs)** derived from omega-3 and omega-6 polyunsaturated fatty acids that actively promote the resolution phase of inflammation. - **Lipoxins** (from arachidonic acid) inhibit neutrophil chemotaxis and promote macrophage-mediated clearance of apoptotic cells. - **Resolvins** (from EPA and DHA) actively terminate inflammatory signals, reduce neutrophil infiltration, and enhance bacterial clearance. - **Protectins** promote resolution by limiting neutrophil recruitment and enhancing clearance of inflammatory debris. - These mediators represent the **endogenous "stop signals"** that actively resolve inflammation rather than simply suppressing it. *IL-10, IL-1 receptor antagonist, and TGF-β* - While these have **anti-inflammatory** effects, they are not classified as primary resolution mediators. - **IL-10** inhibits pro-inflammatory cytokine synthesis and suppresses immune responses (immunosuppressive rather than pro-resolving). - **IL-1 receptor antagonist (IL-1Ra)** blocks IL-1 signaling, preventing inflammation amplification. - **TGF-β** promotes tissue repair and has immunosuppressive functions. - These are **anti-inflammatory mediators** that prevent or dampen inflammation, distinct from specialized pro-resolving mediators that actively orchestrate the resolution process. *TNF-alpha, IL-1, and CRP* - **TNF-alpha** and **IL-1** are classic **pro-inflammatory cytokines** that initiate and amplify inflammation. - **CRP (C-reactive protein)** is an acute-phase reactant and biomarker of inflammation, not a mediator of resolution. *Interferon-gamma and IL-12* - **IFN-γ** and **IL-12** promote **Th1 immune responses** and cellular immunity. - These are pro-inflammatory mediators involved in host defense against intracellular pathogens, not resolution of inflammation.

Q: Pseudomembranous colitis, all are true except:

Blood in stools is a common feature. ***Blood in stools is a common feature*** - While diarrhea is a hallmark of **pseudomembranous colitis**, **bloody stools** are uncommon and, if present, suggest severe disease or an alternative diagnosis [1]. - The typical presentation involves **watery diarrhea**, abdominal cramps, and fever, not usually overt bleeding [1]. *Toxin A is responsible for clinical manifestation* - **Toxin A (TcdA)** is one of the primary exotoxins produced by *Clostridioides difficile* and contributes significantly to the **inflammation** and fluid secretion seen in pseudomembranous colitis. - It acts as an **enterotoxin**, causing fluid secretion and mucosal damage in the colon [1]. *Summit lesions are early histopathological findings* - **Summit lesions**, also known as "summit pseudomembranes" or **"volcano lesions"**, refer to characteristic histological findings where inflammatory exudates effuse from the tips of damaged crypts. - These are typical early findings in pseudomembranous colitis, demonstrating the focal nature of the **mucosal injury**. *Toxin B is responsible for clinical manifestation* - **Toxin B (TcdB)** is another key exotoxin produced by *Clostridioides difficile*, and it is considered even more **cytotoxic** than Toxin A [1]. - It causes significant **cell damage** and **apoptosis**, playing a crucial role in the development of the pseudomembranes and clinical symptoms [1].

Q: The most common subtype of Non-Hodgkin's lymphoma in India is:

Diffuse large B cell lymphoma. ***Diffuse large B cell lymphoma*** - It is the most common subtype of **Non-Hodgkin's lymphoma** observed in India, reflecting a higher prevalence in the population. - Characterized by **aggressive clinical behavior** [1] and typically presents as a rapidly enlarging mass, often involving lymph nodes or extranodal sites. *Burkitt's lymphoma* - This subtype is known for its **high proliferation rate** and is more common in specific demographics, such as children and immunocompromised individuals. - It typically presents with **jaw lesions** or abdominal masses, which is not typical in the broader Indian population. *Diffuse small cell lymphocytic lymphoma* - More accurately classified as **chronic lymphocytic leukemia** (CLL), it is not the most common subtype of Non-Hodgkin's lymphoma. - Characterized by a **milder clinical course** and presents with lymphocytosis in peripheral blood, lacking aggressive features. *Follicular lymphoma* - This is usually a **low-grade lymphoma** associated with **indolent behavior** and may not be the most commonly diagnosed subtype in India. - It typically involves multiple lymph nodes and is characterized by **nodular patterns on histology**, making it less prevalent than diffuse large B cell lymphoma. Follicular lymphoma is rare in Asian populations [2]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 563-564. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of White Blood Cells, Lymph Nodes, Spleen, and Thymus, pp. 602-604.

Q: Which of the following statements about interleukin-1 is false?

IL-1 inhibits IL-2 production by T-cells.. ***IL-1 inhibits IL-2 production by T-cells*** - This statement is false because **IL-1** actually **enhances the production of IL-2** by T-cells, which is crucial for T-cell proliferation and immune response. - **IL-1 acts synergistically with IL-6 and TNF-α** to promote inflammation and immune cell activation, where IL-2 plays a key role. *The primary source of IL-1 is the monocyte-macrophage system* - This statement is true; **monocytes and macrophages** are the main producers of **IL-1α and IL-1β** upon activation by various stimuli. - Other cells, such as neutrophils, dendritic cells, and endothelial cells, can also produce IL-1, but monocytes and macrophages are the predominant source. *IL-1 is an endogenous pyrogen* - This statement is true; **IL-1** is a potent **endogenous pyrogen** that acts on the hypothalamus to induce fever, a hallmark of the acute phase response. - It triggers prostaglandin synthesis in the hypothalamus, leading to an elevation in the body's thermoregulatory set point. *IL-1 promotes acute phase protein synthesis in the liver* - This statement is true; **IL-1** is a key mediator that stimulates **hepatocytes** to produce **acute phase proteins**, such as C-reactive protein and serum amyloid A. - This hepatic response is part of the innate immune system's effort to control infection and inflammation.

Q: Which of the following is not an acute phase reactant?

Endothelin. ***Endothelin*** - Endothelin is a **vasoconstrictive peptide** primarily involved in regulating **blood vessel tone** and blood pressure. - While it plays a role in processes like inflammation and tissue repair, it is not synthesized or regulated in the same rapid, systemic manner as a classic acute phase reactant. *C-reactive protein* - **C-reactive protein (CRP)** is a rapidly responding acute phase reactant produced by the liver in response to **inflammation**, infection, and tissue injury. - Its levels can rise dramatically within hours of an inflammatory stimulus and are used as a marker for disease activity. *Haptoglobin* - **Haptoglobin** is an acute phase reactant that binds to free **hemoglobin** released from red blood cells during hemolysis, preventing oxidative damage. - Its levels typically increase during acute inflammation or infection, although it can also decrease with severe hemolysis. *Fibrinogen* - **Fibrinogen** is a critical acute phase protein involved in the **coagulation cascade** and wound healing. - Its concentration increases significantly during acute inflammation, contributing to the elevated **erythrocyte sedimentation rate (ESR)**.

Q: ABO isoantibodies are of which class?

IgM. ***IgM*** - Naturally occurring **ABO isoantibodies** are predominantly of the **IgM class**. - These **pentameric antibodies** are highly effective at causing **agglutination** of incompatible red blood cells, which is crucial in transfusion reactions [1]. *IgG* - While IgG antibodies can be formed against ABO antigens (e.g., in hemolytic disease of the newborn), the **naturally occurring isoantibodies** are primarily IgM. - IgG antibodies are **monomeric** and can cross the **placenta**, which is a key difference from the primary IgM ABO antibodies. *IgD* - **IgD** antibodies are primarily found on the surface of **B cells** and play a role in B cell activation. - They are **not a primary mediator** of ABO isoantibody response or red blood cell agglutination. *IgA* - **IgA** antibodies are predominantly found in **mucosal secretions** and play a role in mucosal immunity. - While some IgA may be present, it is **not the predominant class** for naturally occurring ABO isoantibodies involved in transfusion reactions. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 154-155.

Q: What is the most common site for carcinoid tumor?

Ileum. ***Ileum*** - The **ileum** is the most common site for carcinoid tumors, accounting for nearly **50%** of cases [1]. - Carcinoid tumors arise from **neuroendocrine cells** in the gastrointestinal tract, with the ileum being particularly common due to its abundant neuroendocrine tissue [1]. *Appendix* - While carcinoid tumors can occur in the **appendix**, they represent a smaller proportion compared to those found in the ileum. - Typical carcinoid tumors in the appendix are often **asymptomatic** and usually detected incidentally. *Lung* - Though lung carcinoids exist, they represent a different classification of carcinoid tumors, primarily occurring in the **bronchial tree** [2]. - They are less common than those in the gastrointestinal tract, particularly the ileum. *Esophagus* - Carcinoid tumors are rare in the **esophagus** and typically have different presentations compared to gastrointestinal carcinoids. - The esophagus is not a common site for carcinoid tumors, which are primarily found in the intestinal tract. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 780-781. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, p. 727.

Question 1

Macrophages are converted to epithelioid cells by which cytokine?

Accepted Answer

IFN-γ

Answer

TNF-α

Answer

TGF-β

Answer

IL-4

Question 2

Which mediators are involved in the resolution of inflammation?

Accepted Answer

Resolvins, protectins, and lipoxins

Answer

TNF Alfa, IL-1, and CRP

Answer

IL-10, IL-1 receptor antagonist, and TGF-β

Answer

Interferon-gamma and IL-12

Question 3

Which of the following statements about wound healing is false?

Accepted Answer

Hematomas promote wound healing

Answer

Inhibited by diabetes mellitus (DM)

Answer

Inhibited by foreign body

Answer

Inhibited by infection

Question 4

Pseudomembranous colitis, all are true except:

Accepted Answer

Blood in stools is a common feature

Answer

Toxin A is responsible for clinical manifestation

Answer

Summit lesions are early histopathological findings

Answer

Toxin B is responsible for clinical manifestation

Question 5

The most common subtype of Non-Hodgkin's lymphoma in India is:

Accepted Answer

Diffuse large B cell lymphoma

Answer

Diffuse small cell lymphocytic lymphoma

Answer

Follicular lymphoma

Answer

Burkitt's lymphoma

Question 6

Which of the following statements about interleukin-1 is false?

Accepted Answer

IL-1 inhibits IL-2 production by T-cells.

Answer

IL-1 is an endogenous pyrogen.

Answer

The primary source of IL-1 is the monocyte-macrophage system.

Answer

IL-1 promotes acute phase protein synthesis in the liver.

Question 7

Which of the following is not an acute phase reactant?

Accepted Answer

Endothelin

Answer

C-reactive protein

Answer

Haptoglobin

Answer

Fibrinogen

Question 8

ABO isoantibodies are of which class?

Accepted Answer

IgM

Answer

IgG

Answer

IgD

Answer

IgA

Question 9

What is a watershed infarct in the brain?

Accepted Answer

Occurs in the border zones between major arteries

Answer

Occurs in the areas supplied by only one artery

Answer

Occurs in the terminal portion of main arteries

Answer

Occurs only in areas with complete arterial occlusion

Question 10

What is the most common site for carcinoid tumor?

Accepted Answer

Ileum

Answer

Lung

Answer

Esophagus

Answer

Appendix

NEET-PG 2013 — Pathology