NEET-PG 2013 - Pathology Practice Questions

Q: Donath-Landsteiner antibody is seen in?

Paroxysmal cold hemoglobinuria. ***Paroxysmal cold hemoglobinuria*** - **Donath-Landsteiner antibody** is a **biphasic IgG autoantibody** that binds to red blood cells in the cold and causes **hemolysis** upon warming, characteristic of paroxysmal cold hemoglobinuria. - This antibody has **anti-P specificity**, meaning it targets the P antigen on red blood cells, leading to complement activation and cell lysis. *PNH* - **Paroxysmal nocturnal hemoglobinuria** (PNH) is characterized by a deficiency in **GPI-anchored proteins** on red blood cells, notably **CD55** and **CD59**, making them susceptible to complement-mediated lysis. - It is not associated with the Donath-Landsteiner antibody; rather, it is identified by **flow cytometry** showing absence of CD55/CD59. *Waldenstrom's macroglobulinemia* - This is a **B-cell lymphoma** characterized by the overproduction of **monoclonal IgM antibodies**, leading to hyperviscosity syndrome and other symptoms. - It does not involve Donath-Landsteiner antibodies or cold-induced hemolysis in the same manner as paroxysmal cold hemoglobinuria. *Malaria* - **Malaria** is caused by **Plasmodium parasites** that infect and destroy red blood cells, leading to hemolytic anemia and fever. - While it causes **hemolysis**, it is not mediated by the Donath-Landsteiner antibody; the destruction is primarily due to parasitic replication and immune responses against infected cells.

Q: Which of the following substances is not classified as a carcinogen for bladder cancer?

Isopropyl alcohol. ***Isopropyl alcohol*** - Research does not link **isopropyl alcohol** to an increased risk of bladder cancer, making it a non-carcinogenic substance in this context. - It is commonly used as a solvent and antiseptic, but has not shown **urogenic carcinogenicity** in studies. *Phenacetin* - **Phenacetin** is an analgesic that has been associated with an increased risk of bladder cancer, particularly due to its metabolite, which can be nephrotoxic. - Its use has significantly declined due to its carcinogenic effects on the urinary system. *Benzidine* - **Benzidine** is a well-known bladder carcinogen, primarily linked to the dye industry, where exposure has led to increased rates of bladder cancer [1]. - This substance has been implicated in **urothelial carcinoma** due to its mutagenic properties. *Acrolein* - **Acrolein** is a toxic compound that can cause bladder irritation and has been studied for its potential carcinogenic effects related to bladder cancer. - It is released during the combustion of materials and is known to contribute to **chemical injury** in the bladder. **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. 217-218.

Q: Caseous necrosis is seen in -

Tuberculosis. ***Tuberculosis*** - **Caseous necrosis** is the **pathognomonic** and **most characteristic** form of necrosis seen in **tuberculosis (TB)** caused by *Mycobacterium tuberculosis* [1]. - It appears as a **cheesy, friable, granular material** in the center of **tuberculous granulomas** (tubercles) [1], [2]. - The unique **lipid-rich cell wall** of *M. tuberculosis* combined with the host's **type IV hypersensitivity reaction** results in this distinctive pattern of tissue destruction [2]. - This is a **classic histopathological hallmark** of TB and is essential for diagnosis [2]. *Treponemal infection* - **Syphilis**, caused by *Treponema pallidum*, causes **gummatous necrosis**, NOT caseous necrosis [3]. - Gummas have a **rubbery consistency** and different histological appearance compared to the cheesy, friable caseous necrosis. - While syphilis produces granulomatous inflammation, the necrosis pattern is distinctly different from TB [3]. *CMV infection* - **Cytomegalovirus (CMV)** infection typically causes **coagulative necrosis** with **cytopathic effects** (enlarged cells with intranuclear and intracytoplasmic inclusions - "owl's eye" appearance) [3]. - Does NOT produce caseous necrosis. *Staphylococcal infection* - **Staphylococcal infections** (e.g., *Staphylococcus aureus*) cause **liquefactive necrosis** leading to **abscess formation** [3]. - Dead cells are enzymatically digested into **liquid pus**, completely different from the solid, cheesy appearance of caseous necrosis. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Cellular Responses to Stress and Toxic Insults: Adaptation, Injury, and Death, p. 55. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 383-384. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, p. 360.

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 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: 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: 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: 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: Hose pipe appearance of intestine is a feature of

Ulcerative colitis. ***Crohns disease*** - The **hose pipe appearance** of the intestine on imaging is due to **transmural inflammation** and **strictures**, characteristic of Crohn's disease [1]. - This feature indicates a **narrowed lumen** due to fibrosis, often affecting the small intestine or colon [1]. *Malabsorption syndrome* - This condition is primarily associated with **nutrient absorption issues**, not structural changes in the intestine. - It typically presents with **diarrhea**, **weight loss**, and **malnutrition**, lacking the characteristic imaging findings. *Ulcerative colitis* - Usually presents with **continuous lesions** confined to the colonic mucosa, leading to ulcers and inflammation but not a **hose pipe appearance**. - Symptoms include **bloody diarrhea** and **abdominal pain**, distinctly different from Crohn's disease. *Hirsprung disease* - A congenital condition causing **intestinal obstruction** due to the absence of ganglion cells, leading to **dilated proximal bowel** rather than a hose pipe appearance. - Typically presents in infants with **severe constipation** and **abdominal distension**, unrelated to imaging features seen in Crohn's disease. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Alimentary System Disease, pp. 366-367.

Question 1

Donath-Landsteiner antibody is seen in?

Accepted Answer

Paroxysmal cold hemoglobinuria

Answer

PNH

Answer

Waldenstrom's macroglobulinemia

Answer

Malaria

Question 2

Which of the following substances is not classified as a carcinogen for bladder cancer?

Accepted Answer

Isopropyl alcohol

Answer

Acrolein

Answer

Phenacetin

Answer

Benzidine

Question 3

Caseous necrosis is seen in -

Accepted Answer

Tuberculosis

Answer

CMV infection

Answer

Treponemal infection

Answer

Staphylococcal infection

Question 4

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 5

Which of the following is not an acute phase reactant?

Accepted Answer

Endothelin

Answer

C-reactive protein

Answer

Haptoglobin

Answer

Fibrinogen

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

ABO isoantibodies are of which class?

Accepted Answer

IgM

Answer

IgG

Answer

IgD

Answer

IgA

Question 8

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 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

Hose pipe appearance of intestine is a feature of

Accepted Answer

Ulcerative colitis

Answer

Malabsorption syndrome

Answer

Crohn's disease

Answer

Hirschsprung disease

NEET-PG 2013 — Pathology