General Pathology — MCQs

General Pathology Indian Medical PG Practice Questions and MCQs

Question 1391: 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 1392: Vitamin A deficiency leads to metaplasia of which type of epithelium?

A. None of the options
B. Columnar epithelium (Correct Answer)
C. Cuboidal epithelium
D. Squamous epithelium

Explanation: ***Squamous epithelium*** - Vitamin A deficiency leads to a condition known as **xerophthalmia**, which involves the metaplasia of conjunctival epithelium from columnar to **squamous** type [1]. - It is crucial for maintaining the integrity of **epithelial tissues**, particularly in the respiratory and gastrointestinal tracts, leading to squamous metaplasia [1]. *None* - This option fails to recognize that **metaplasia** occurs specifically in response to deficiency of vitamin A. - The implication that no changes occur is incorrect, as significant alterations to epithelial types are noted in deficiency states [1]. *Columnar epithelium* - While columnar epithelium can undergo metaplasia, it typically becomes squamous in vitamin A deficiency, not remaining solely columnar [2]. - Conditions like intestinal metaplasia occur due to other pathways, such as chronic irritation, not directly linked to vitamin A deficiency. *Both* - This option suggests metaplasia in both epithelium types, which is misleading as vitamin A deficiency primarily affects **squamous** epithelium, not columnar directly [1]. - The typical response is a loss of **columnar** cells and their replacement with **squamous** cells, rather than dual metaplasia [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Central Nervous System Synapse, pp. 445-446. [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, p. 49.

Question 1393: What is the earliest detectable cellular change following injury?

A. Membrane damage
B. Diminished ATP (Correct Answer)
C. Release of lysosomal enzymes
D. Mitochondrial dysfunction

Explanation: ***Mitochondrial dysfunction*** [1] - Mitochondrial dysfunction is often the **first metabolic change** following cellular injury, impacting ATP production [1]. - Since mitochondria are crucial for energy homeostasis, dysfunction can lead to severe cellular effects and initiate the injury cascade [1]. *Diminished ATP* [1] - While diminished ATP is a consequence of injury, it is not the **initial sign**; it results from mitochondrial dysfunction [1]. - ATP depletion typically occurs **after** mitochondrial impairment has begun, indicating further progression of injury [1]. *Membrane damage* [1] - Membrane integrity can be compromised due to **various insults**, but this happens **after** mitochondrial dysfunction when the cell's economy fails [1]. - Early injury signs primarily involve **functional deficits** rather than structural changes like membrane damage [1]. *Release of lysosomal enzymes* - Release of lysosomal enzymes indicates **cell death** or severe cellular injury, which occurs later in the injury process. - It is not a primary indicator, but rather a response to **critical conditions** post-injury. **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. 49-62.

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: 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 1396: 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 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: Hypertrophy is -

A. Increase in cell number
B. Increase in cell size (Correct Answer)
C. Decrease in cell number
D. Decrease in cell size

Explanation: ***Increase in cell size*** - **Hypertrophy** is defined as an increase in the **size of individual cells** [1], leading to an increase in the size of the organ or tissue [2]. - This cellular adaptation occurs when cells are subjected to increased workload or demand, such as in **muscle cells** in response to exercise or **cardiac myocytes** in hypertension [2]. *Increase in cell number* - An increase in **cell number** is termed **hyperplasia** [1]. - Hyperplasia typically occurs in tissues capable of **mitotic division**, leading to an increase in the overall size of the tissue or organ due to more cells [1]. *Decrease in cell number* - A decrease in **cell number** can result from **atrophy** (loss of cells) or programmed cell death (**apoptosis**). - This process is seen in various physiological or pathological conditions, leading to a reduction in organ size. *Decrease in cell size* - A decrease in the **size of individual cells** is known as **atrophy** [3]. - Atrophy often occurs due to reduced workload, loss of innervation, diminished blood supply, or inadequate nutrition [3]. **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. 85-88. [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. 45-46. [3] 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. 90-91.

Question 1400: What does Prussian blue staining specifically detect in histology?

A. Ferric iron (Correct Answer)
B. Ferrous iron
C. Glycogen
D. Lipids

Explanation: ***Ferric iron*** - The **Prussian blue reaction**, also known as Perls' stain, specifically identifies **ferric iron (Fe3+)** in tissue sections. - This stain is crucial for diagnosing conditions involving **iron overload**, such as hemochromatosis or hemosiderosis, by highlighting iron deposits as blue. *Ferrous iron* - The Prussian blue stain does **not react with ferrous iron (Fe2+)**; it specifically targets the ferric (oxidized) state of iron. - While ferrous iron is present in the body, it is not detected by this particular staining method for routine histological assessment of iron stores. *Glycogen* - **Glycogen** is a polysaccharide storage molecule and is typically stained using the **Periodic Acid-Schiff (PAS) stain**, which produces a magenta color. - Prussian blue staining is entirely unrelated to the detection of glycogen and would not highlight these molecules in tissue. *Lipids* - **Lipids** are fats and are typically stained with lipid-soluble dyes like **Oil Red O** or **Sudan Black**, especially in frozen sections to preserve their structure. - Prussian blue stain has no affinity for lipids and therefore cannot be used to detect them in histological samples.

Practice by Chapter

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