General Pathology — MCQs

General Pathology Indian Medical PG Practice Questions and MCQs

Question 1391: Dystrophic calcification is associated with which of the following conditions?

A. Milk alkali syndrome
B. Hyperparathyroidism
C. Vitamin A intoxication
D. Atheromatous plaques and other conditions. (Correct Answer)

Explanation: ***Atheromatous plaque*** - Dystrophic calcification occurs in areas of **tissue damage** and is commonly observed in atheromatous plaques, where lipid accumulation leads to inflammation and calcification. - This type of calcification is a result of **necrosis** or tissue injury, typically seen in the vascular system, particularly in **atherosclerotic lesions**. *Vitamin A intoxication* - Vitamin A toxicity is characterized by **hypervitaminosis A**, which can lead to symptoms such as **nausea**, **headaches**, and **blurred vision**, but is not directly linked to dystrophic calcification. - The calcifications often associated with vitamin A excess are more related to **metabolic processes** rather than **dystrophic calcification** in damaged tissue. *Milk alkali syndrome* - Milk alkali syndrome is caused by excessive intake of **calcium** and **alkali**, leading to **hypercalcemia** and potentially **metastatic calcification** [1][2], not dystrophic calcification. - It manifests with symptoms like **nausea**, **vomiting**, and **altered mental status**, but does not involve the same mechanism of tissue damage as seen in dystrophic calcification. *Hyperparathyroidism* - This condition can cause **hypercalcemia** and **metastatic calcification** [1][2] due to increased calcium levels in the blood, primarily affecting soft tissues. - Dystrophic calcification specifically refers to calcification occurring in damaged or necrotic tissue, which is not a hallmark of primary hyperparathyroidism. **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. 134-135. [2] 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, pp. 76-77.

Question 1392: What is the characteristic feature of thermal injury in tissues?

A. Coagulation necrosis of tissue proteins (Correct Answer)
B. Ruptured blood vessels or clotted blood
C. Irregular margins due to thermal damage
D. Smooth tissue margins due to healing

Explanation: ***Coagulation necrosis of tissue proteins*** - **Thermal injury** causes cell proteins to **denature** and coagulate, leading to cell death and the formation of a solid, opaque mass. - This process is characteristic of **coagulation necrosis**, where the basic tissue architecture is preserved for a period due to enzyme inactivation. *Irregular margins due to thermal damage* - While thermal damage can result in irregular margins, this is a **gross morphological feature** rather than the fundamental cellular and biochemical characteristic of thermal injury. - **Coagulation necrosis** is the underlying histological change that explains the tissue's appearance. *Ruptured blood vessels or clotted blood* - **Ruptured blood vessels** and **clotted blood** can occur with thermal injury, particularly in severe burns, but these are secondary effects or complications, not the primary "characteristic feature" of the tissue injury itself. - The fundamental characteristic is the **denaturation** of cellular proteins. *Smooth tissue margins due to healing* - **Smooth tissue margins** are typically associated with the **healing process** (e.g., re-epithelialization, scar formation) much later in the course after the initial thermal injury. - This option describes a **late-stage reparative process**, not the immediate characteristic feature of acute thermal tissue damage.

Question 1393: Which stain is used for staining the nucleus?

A. Safranin
B. Fast green
C. Hematoxylin (Correct Answer)
D. Erythrosine

Explanation: ***Hematoxylin*** - **Hematoxylin** is a basic dye that stains **acidic structures** like the **nucleic acids** (DNA and RNA) in the nucleus a **blue-purple** color. - It is extensively used in **histology and pathology** to visualize cell nuclei, making it a cornerstone of the **hematoxylin and eosin (H&E) stain**. *Safranin* - **Safranin** is a basic dye often used as a counterstain in some protocols and stains **collagen** and **mast cell granules** reddish-orange. - It is also used in bacteriology to stain gram-negative bacteria **red**. *Fast green* - **Fast green** is an acidic dye that stains **basic proteins** in the **cytoplasm and collagen** green or blue-green. - It is commonly used as a counterstain in plant histology or in combination with other dyes to highlight specific tissue components. *Erythrosine* - **Erythrosine** is a pink/red acidic dye used as a counterstain, primarily staining **protein-rich cytoplasm** and other basic structures pink. - It is less commonly used in routine histology compared to eosin, but can be found in some specialized staining methods.

Question 1394: What is the first stage of tissue damage in an alkali burn?

A. Coagulation necrosis
B. Tissue necrosis
C. Full thickness necrosis
D. Liquefactive necrosis (Correct Answer)

Explanation: ***Liquefactive necrosis*** - Alkali burns cause **liquefactive necrosis** as the **first stage of tissue damage**, which is the hallmark mechanism of alkali injury. - The alkali reacts with tissue lipids causing **saponification of fats** and **protein denaturation**, resulting in dissolution and liquefaction of tissues. - This liquefactive process allows the alkali to **penetrate deeper** into tissues progressively, causing ongoing and extensive damage as it continues to dissolve cellular structures. - This is why alkali burns are generally more severe than acid burns, despite potentially appearing less dramatic initially. *Coagulation necrosis* - **Coagulation necrosis** is characteristic of **acid burns**, not alkali burns. - Acids cause proteins to coagulate and denature, forming a **protective eschar** (dry, hard layer). - This eschar acts as a barrier that **limits penetration** of the acid into deeper tissues, often resulting in less extensive damage compared to alkali burns. *Tissue necrosis* - **Tissue necrosis** is a general term for cell death but does not specify the mechanism or type. - While liquefactive necrosis is indeed a type of tissue necrosis, this option is **too broad and non-specific** to answer what the first stage of damage is. - The question requires identification of the specific **pattern or mechanism** of necrosis, not just a general acknowledgment that cell death occurs. *Full thickness necrosis* - **Full-thickness necrosis** describes the **extent or depth** of tissue damage (involving all layers), not the mechanism or type of cellular injury. - While severe alkali burns can eventually progress to full-thickness necrosis, this is a **consequence of progressive liquefaction**, not the initial cellular process. - This term describes "how deep" rather than "how" the damage occurs.

Question 1395: Neurofibromatosis shows which of the following mode of inheritance ?

A. AD (Correct Answer)
B. AR
C. X linked dominant
D. X linked recessive

Explanation: ***AD*** - **Neurofibromatosis type 1 (NF1)** and **Neurofibromatosis type 2 (NF2)** are both classic examples of **autosomal dominant (AD)** inheritance [1]. - This means that only one copy of the altered gene (on a non-sex chromosome) is sufficient to cause the disorder, and there is a **50% chance** of passing the condition to each child [1]. *AR* - **Autosomal recessive (AR)** disorders require two copies of the altered gene (one from each parent) for the condition to manifest [1]. - Examples include **cystic fibrosis** and **sickle cell anemia**, which have a different pattern of inheritance than neurofibromatosis. *X linked dominant* - **X-linked dominant** disorders are caused by a mutation on the X chromosome, where only one copy of the mutated gene is needed for the condition to appear [1]. - These disorders typically affect females more often than males and show a specific inheritance pattern through X chromosome transmission, which is not seen in neurofibromatosis. *X linked recessive* - **X-linked recessive** disorders are also caused by mutations on the X chromosome but typically affect males more severely as they only have one X chromosome [1]. - Females are often carriers, and the inheritance pattern differs significantly from the clinical presentation and genetic transmission of neurofibromatosis. **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. 53-54.

Question 1396: Which of the following conditions is characterized by the absence of Barr bodies?

A. Klinefelter syndrome
B. Down's syndrome
C. Marfan's syndrome
D. Turner syndrome (Correct Answer)

Explanation: ***Turner syndrome*** - Females with **Turner syndrome** have a 45,XO karyotype, meaning they have only one X chromosome. - Since a **Barr body** is formed from the inactivation of one X chromosome in normal females (46,XX), individuals with Turner syndrome have **no Barr bodies** due to the absence of a second X chromosome. *Klinefelter syndrome* - Individuals with **Klinefelter syndrome** typically have a 47,XXY karyotype, meaning they have two X chromosomes. - The presence of two X chromosomes leads to the formation of **one Barr body** (from inactivation of one of the two X chromosomes), making this option incorrect. *Down's syndrome* - **Down's syndrome** is caused by trisomy 21 (extra copy of chromosome 21), which is an autosomal abnormality. - The number of Barr bodies in individuals with Down's syndrome depends on their sex chromosome complement (normal pattern: 46,XX females have one Barr body, 46,XY males have none). *Marfan's syndrome* - **Marfan's syndrome** is an autosomal dominant disorder affecting connective tissue, caused by a mutation in the **FBN1 gene**. - This condition does not involve abnormalities in sex chromosomes, so the number of Barr bodies follows the normal pattern (one in 46,XX females, none in 46,XY males).

Question 1397: In which condition are positive Periodic Acid-Schiff (PAS) macrophages typically observed?

A. None of the options
B. AIDS
C. Crohn's disease
D. Whipple's disease (Correct Answer)

Explanation: ***Whipple's disease*** - **Whipple's disease** is characterized by the presence of **foamy macrophages** in the lamina propria of the small intestine [1]. - These macrophages contain intracellular rod-shaped bacilli and are strongly **Periodic Acid-Schiff (PAS)-positive** due to the presence of bacterial glycoproteins [1]. *Crohn's disease* - Crohn's disease is an **inflammatory bowel disease** characterized by transmural inflammation and non-caseating granulomas. - While macrophages are present, they are not typically **PAS-positive** in the distinctive way seen in Whipple's disease. *AIDS* - AIDS (Acquired Immunodeficiency Syndrome) is caused by the **Human Immunodeficiency Virus (HIV)** and leads to immune compromise. - While various opportunistic infections and pathologies can occur, **PAS-positive macrophages** are not a characteristic diagnostic feature of HIV/AIDS itself. *None of the options* - This option is incorrect because **Whipple's disease** clearly matches the description of having positive PAS macrophages. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 798-799.

Question 1398: What is the key pathophysiological difference between acid and alkali injuries in terms of tissue necrosis?

A. Acid injuries cause coagulative necrosis
B. Alkali injuries lead to deeper tissue damage
C. Acid injuries are less severe than alkali injuries
D. Alkali injuries cause liquefactive necrosis (Correct Answer)

Explanation: ***Alkali injuries cause liquefactive necrosis*** - **Alkali burns** result in **liquefaction necrosis**, which involves the dissolution of tissue and cells, leading to a much deeper and progressive injury as the alkali penetrates further into tissues. - This is the **key pathophysiological difference** that distinguishes alkali from acid injuries - the TYPE of necrosis (liquefactive vs coagulative). - This type of necrosis allows the alkali to continue damaging underlying tissues and can lead to more extensive and severe scarring and complications. *Acid injuries cause coagulative necrosis* - While this statement is **medically true**, it only describes what acids do without explicitly stating the **difference** or comparison with alkali injuries. - The question asks for the KEY **difference**, and this option presents only one half of the comparison. - **Acid burns** typically cause **coagulation necrosis**, forming a coagulum or eschar that precipitates proteins and creates a barrier, thereby limiting the depth of penetration. - The correct answer (alkali → liquefactive necrosis) better captures the distinguishing pathophysiological feature. *Alkali injuries lead to deeper tissue damage* - This statement is true but serves as a **consequence** of the underlying **liquefactive necrosis** rather than the primary pathophysiological mechanism itself. - The liquefaction process continuously destroys cells and extracellular matrix, enabling the caustic agent to propagate deeply into the tissue. - This describes the OUTCOME rather than the KEY pathophysiological mechanism. *Acid injuries are less severe than alkali injuries* - This is a **generalization about severity** rather than identifying the specific pathophysiological mechanism of tissue death. - While generally true due to the **coagulation necrosis** limiting the depth of penetration of acids, severity can vary based on concentration, duration of exposure, and other factors. - The formation of a protective eschar in acid burns often prevents further significant tissue destruction, unlike the progressive damage seen in alkali burns.

Question 1399: Which molecule is primarily responsible for nuclear fragmentation during apoptosis?

A. Caspases (Correct Answer)
B. Apaf - 1
C. Oxygen free radicals
D. Endonuclease G

Explanation: ***Caspases*** - **Caspases** are a family of proteases that play a central role in the execution phase of apoptosis, including the **cleavage of nuclear proteins** and DNA fragmentation [1]. - Specifically, **executioner caspases** (e.g., caspase-3, -6, -7) activate **CAD (caspase-activated DNase)** by cleaving its inhibitor ICAD, leading to **nuclear fragmentation** and DNA laddering [1]. - This is the **primary mechanism** of nuclear breakdown in apoptosis. *Apaf-1* - **Apaf-1 (apoptotic protease activating factor 1)** is an adaptor protein that, upon activation by cytochrome c, forms the **apoptosome** [1]. - While essential for **caspase activation** (specifically caspase-9), Apaf-1 does not directly cleave nuclear components or cause fragmentation itself [1]. *Oxygen free radicals* - **Oxygen free radicals** (reactive oxygen species) can induce cellular damage and stress, and in high concentrations, can trigger apoptosis [2]. - However, they are generally upstream initiators of apoptosis pathways and do not directly mediate nuclear fragmentation; this process is carried out by **caspases**. *Endonuclease G* - **Endonuclease G** is a mitochondrial nuclease released during apoptosis that can contribute to DNA degradation. - However, it plays a **secondary role** and acts in a caspase-independent manner, whereas **caspases** remain the primary executors of nuclear fragmentation in apoptosis. **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, pp. 64-67. [2] 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. 100-101.

Question 1400: Which of the following is derived from fibroblast cells?

A. MMP2
B. Collagen (Correct Answer)
C. Angiopoietin
D. TGF-β

Explanation: ***Collagen*** - Collagen is a structural protein that is predominantly produced by **fibroblast cells** in the extracellular matrix [1][2]. - It provides tensile strength and structural support to various tissues, playing a crucial role in wound healing and tissue repair [2]. *TGF-13* - Transforming Growth Factor-beta 1 (TGF-β1) is primarily produced by **immune cells** and is involved in cell growth and differentiation, not primarily by fibroblasts. - It plays a role in **fibrosis** and inflammation, but is not directly synthesized by fibroblast cells themselves. *MMP2* - Matrix Metalloproteinase-2 (MMP-2) is produced by various cell types, including **endothelial and epithelial cells**, but not predominantly by fibroblasts. - It is involved in the degradation of **extracellular matrix** components rather than being a product of fibroblast synthesis. *Angiopoietin* - Angiopoietin is primarily secreted by **endothelial cells** and plays a significant role in blood vessel formation and maturation. - It is not derived from fibroblast cells and is unrelated to their primary function of producing the extracellular matrix. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. With Illustrations By, pp. 31-32. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. With Illustrations By, pp. 34-35.

Practice by Chapter

Cell Injury and Cell Death

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Adaptations of Cellular Growth

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Hemodynamic Disorders

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Genetic Disorders

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Environmental Pathology

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Molecular Basis of Disease

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