General Pathology — MCQs

General Pathology Indian Medical PG Practice Questions and MCQs

Question 1151: All of the following are types of genetic polymorphism, except?

A. Copy number variation
B. Pleiotropism (Correct Answer)
C. Single nucleotide polymorphisms
D. None of the above

Explanation: **Explanation:** The correct answer is **Pleiotropism** because it refers to a phenotypic phenomenon rather than a structural variation in the DNA sequence (polymorphism). **1. Why Pleiotropism is the correct answer:** Pleiotropism is a genetic condition where a **single gene mutation** leads to multiple, seemingly unrelated phenotypic effects across different organ systems. For example, in Marfan Syndrome, a mutation in the *FBN1* gene affects the skeletal system, eyes, and cardiovascular system. It describes the *expression* of a gene, not a variation in the DNA sequence itself. **2. Why the other options are incorrect:** * **Single Nucleotide Polymorphisms (SNPs):** These are the most common type of genetic variation [1]. They involve a variation at a **single base pair** (e.g., C replaced by T) [2]. To be considered a polymorphism, the variant must occur in at least 1% of the population. * **Copy Number Variations (CNVs):** These involve larger stretches of DNA (ranging from one kilobase to several megabases) that are either deleted or duplicated. CNVs account for a significant portion of human genetic diversity and are a recognized form of polymorphism. **Clinical Pearls for NEET-PG:** * **SNPs** are biallelic and are extensively used in **Genome-Wide Association Studies (GWAS)** to identify susceptibility to common diseases like Type 2 Diabetes and Hypertension [1]. * **Genetic Polymorphism** is defined as a locus where two or more alleles occur in the population with a frequency of at least **1%** [2]. * **Variable Expressivity** (different degrees of severity in individuals with the same genotype) and **Reduced Penetrance** (carrying the gene but not showing the trait) are often confused with pleiotropism; remember that pleiotropism specifically refers to **multiple organ involvement**. **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. 56-57. [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. 55-56.

Question 1152: Which of the following is the most common fixative used in electron microscopy?

A. Glutaraldehyde (Correct Answer)
B. Formalin
C. Picric acid
D. Absolute alcohol

Explanation: **Explanation:** **1. Why Glutaraldehyde is the Correct Answer:** Glutaraldehyde is the gold standard fixative for **Electron Microscopy (EM)** because it is a dialdehyde that forms extensive cross-links between proteins. This rapid and stable cross-linking preserves the **ultrastructural details** of organelles (like mitochondria and endoplasmic reticulum) with high fidelity. For EM, tissues are typically "double-fixed": first with **Glutaraldehyde** (to preserve morphology) and subsequently with **Osmium Tetroxide** (to preserve lipids and provide electron density/contrast). **2. Analysis of Incorrect Options:** * **Formalin (10% Neutral Buffered Formalin):** This is the most common fixative for **Light Microscopy**. While it preserves general tissue architecture well, it does not preserve ultrastructural details sufficiently for the high magnification of EM. * **Picric Acid:** A component of **Bouin’s solution**, it is excellent for preserving glycogen and delicate tissues (like testes or GI biopsies) but causes significant shrinkage, making it unsuitable for EM. * **Absolute Alcohol:** This is a **dehydrating/precipitating fixative**. It is primarily used for cytological smears or when preserving pigments and enzymes, but it causes severe tissue distortion and is never used for EM. **3. High-Yield Clinical Pearls for NEET-PG:** * **Best Fixative for EM:** Glutaraldehyde (followed by Osmium Tetroxide). * **Best Fixative for Light Microscopy:** 10% Neutral Buffered Formalin. * **Best Fixative for Renal Biopsy (Immunofluorescence):** Michel’s medium (transport medium). * **Best Fixative for Lipids:** Osmium Tetroxide. * **Fixative for Gout (Urate crystals):** Absolute Alcohol (as water-based fixatives dissolve the crystals).

Question 1153: What does not occur in lysosomal storage disorders?

A. Increased number and size of lysosomes
B. Lysis of the cell (Correct Answer)
C. Apoptosis of the cell
D. Accumulation of polyubiquitinated proteins

Explanation: **Explanation:** Lysosomal Storage Disorders (LSDs) are a group of inherited metabolic diseases characterized by the deficiency of specific lysosomal enzymes, leading to the accumulation of undigested substrates [1]. **Why "Lysis of the cell" is the correct answer:** In LSDs, the primary pathology involves the progressive accumulation of metabolites within the endosomal-lysosomal system. This leads to cellular dysfunction and eventual cell death; however, this death occurs via **programmed pathways (Apoptosis)** rather than osmotic or mechanical lysis [1]. The lysosomal membrane usually remains intact for a significant duration; if it were to rupture prematurely (lysis), the release of hydrolytic enzymes would cause necrosis, which is not the hallmark of these chronic storage diseases. **Analysis of Incorrect Options:** * **A. Increased number and size of lysosomes:** This is the cardinal morphological feature. The lack of degradation leads to "clogging" of the cell with enlarged, substrate-filled lysosomes (e.g., Gaucher cells) [1]. * **C. Apoptosis of the cell:** Accumulation of undigested material triggers macrophage activation, oxidative stress, and mitochondrial dysfunction, eventually leading to programmed cell death (Apoptosis) [1]. * **D. Accumulation of polyubiquitinated proteins:** Defective lysosomal function impairs **autophagy** [1]. Since the "trash disposal" system is broken, misfolded and polyubiquitinated proteins that are normally degraded via the autophagic-lysosomal pathway begin to aggregate. **High-Yield Clinical Pearls for NEET-PG:** * **Most common LSD:** Gaucher Disease (Glucocerebrosidase deficiency). * **Only X-linked LSDs:** Fabry Disease and Hunter Syndrome (All others are Autosomal Recessive). * **Cherry Red Spot on Macula:** Seen in Tay-Sachs, Niemann-Pick, and Sandhoff disease [1]. * **Zebra Bodies:** Electron microscopy finding characteristic of Mucopolysaccharidoses and Fabry disease. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, pp. 159-163.

Question 1154: Provisional matrix is made up of?

A. Fibrin
B. Fibronectin
C. Fibrinogen
D. All of the above (Correct Answer)

Explanation: ### Explanation The **provisional matrix** is the initial, temporary extracellular scaffold formed during the early stages of wound healing (specifically the inflammatory and proliferative phases). It serves as a critical bridge that stabilizes the wound and provides a substrate for cell migration [1]. **Why "All of the above" is correct:** Immediately following a vascular injury, the coagulation cascade is activated. 1. **Fibrinogen** (Option C) is leaked from the permeable blood vessels into the extravascular space [1]. 2. Thrombin then converts this fibrinogen into **Fibrin** (Option A) threads, which polymerize to form a meshwork. 3. **Fibronectin** (Option B), a glycoprotein, binds to this fibrin mesh. It acts as a "biological glue," providing specific binding sites (RGD sequences) for integrins on the surface of migrating fibroblasts and endothelial cells. Together, these components form the provisional matrix, which is eventually replaced by a more permanent granulation tissue rich in Type III collagen [1]. **Analysis of Options:** * **A, B, and C:** While each is a component, selecting any single one would be incomplete. The provisional matrix is a complex assembly of all three elements working in synergy to initiate repair. **High-Yield Clinical Pearls for NEET-PG:** * **Function:** The provisional matrix provides the framework for **re-epithelialization** and **angiogenesis** [1]. * **Key Molecule:** **Fibronectin** is the most important adhesive glycoprotein in the provisional matrix. * **Transition:** In the later stages of healing, the provisional matrix (Fibrin/Fibronectin) is degraded by **plasmin** and replaced by **Type III Collagen**, which is eventually remodeled into **Type I Collagen** (the strongest collagen in mature scars) [1]. * **Exam Trap:** Do not confuse the *provisional matrix* (early) with *granulation tissue* (later, characterized by capillaries and fibroblasts) [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 117-119.

Question 1155: The recurrence of pleomorphic adenoma is attributed to which of the following factors?

A. Presence of an incomplete capsule (Correct Answer)
B. Mixed origin
C. Absence of capsule
D. Perineural spread

Explanation: Pleomorphic adenoma (Mixed Tumor) is the most common salivary gland tumor. Despite being benign, it has a notorious tendency for local recurrence if not excised with wide margins [1]. **1. Why the correct answer is right:** The recurrence is primarily attributed to its **incomplete or "pseudocapsule."** Histologically, the tumor often features finger-like projections (pseudopods) that extend through the fibrous capsule into the surrounding normal salivary tissue. During a simple enucleation, these microscopic extensions are left behind, leading to multifocal recurrence [1]. Therefore, the standard surgical treatment is superficial parotidectomy rather than simple enucleation, as simple enucleation carries a recurrence rate approaching 25% [1]. **2. Why the incorrect options are wrong:** * **Mixed origin:** While the tumor is "mixed" (containing epithelial, myoepithelial, and mesenchymal-like components such as chondroid or myxoid tissue), this histological diversity does not cause recurrence. * **Absence of capsule:** Pleomorphic adenoma is generally encapsulated; it is the **incompleteness** and thickness variation of the capsule, rather than its total absence, that is the surgical challenge. * **Perineural spread:** This is a classic feature of **Adenoid Cystic Carcinoma**, not Pleomorphic Adenoma. Perineural invasion is a sign of malignancy and aggressive local behavior. **High-Yield Clinical Pearls for NEET-PG:** * **Most common site:** Parotid gland (Superficial lobe) [1]. * **Most common presentation:** Painless, slow-growing, mobile swelling at the angle of the jaw [1]. * **Histology:** Characterized by "Mixed" appearance (Epithelial elements + Myxoid/Chondroid stroma). * **Risk of Malignancy:** Long-standing cases can transform into **Carcinoma ex Pleomorphic Adenoma** (indicated by sudden rapid growth) [1]. * **Nerve involvement:** Facial nerve palsy is rare in benign pleomorphic adenoma; its presence suggests malignancy. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Head and Neck, pp. 751-753.

Question 1156: In-situ DNA nick end labeling can quantitate what fraction of cells?

A. Cells in apoptotic pathways (Correct Answer)
B. Cells in S phase
C. p53 gene product
D. bcr/abl gene

Explanation: **Explanation:** **TUNEL (Terminal deoxynucleotidyl transferase dUTP Nick End Labeling)** is a specialized laboratory technique used to detect and quantitate cells undergoing **apoptosis**. **Why Option A is Correct:** A hallmark of apoptosis is the activation of endogenous endonucleases (caspase-activated DNase), which cleave genomic DNA into fragments of 180–200 base pairs (creating the characteristic "DNA laddering" on electrophoresis). These breaks result in numerous exposed **3'-hydroxyl (3'-OH) ends** or "nicks." The TUNEL assay uses the enzyme **Terminal deoxynucleotidyl transferase (TdT)** to attach labeled nucleotides (like dUTP) to these 3'-OH ends. The intensity of the labeling is proportional to the degree of DNA fragmentation, allowing for the quantification of apoptotic cells. **Why Other Options are Incorrect:** * **Option B (Cells in S phase):** These are typically identified using **BrdU (Bromodeoxyuridine)** labeling or Ki-67 protein expression, which mark DNA synthesis and active proliferation. * **Option C (p53 gene product):** p53 is a tumor suppressor protein detected via **Immunohistochemistry (IHC)**. While p53 can trigger apoptosis, TUNEL measures the resulting DNA damage, not the protein itself. * **Option D (bcr/abl gene):** This fusion gene (Philadelphia chromosome) is detected using **FISH (Fluorescence In Situ Hybridization)** or **RT-PCR**, not by end-labeling DNA nicks. **High-Yield Clinical Pearls for NEET-PG:** * **DNA Laddering:** A specific feature of apoptosis (not necrosis) seen on agar gel electrophoresis. * **Annexin V:** Another marker for apoptosis; it binds to **Phosphatidylserine**, which flips from the inner to the outer leaflet of the plasma membrane during early apoptosis. * **Caspase-3:** The most common "executioner" caspase involved in both intrinsic and extrinsic pathways.

Question 1157: Which of the following statements is NOT true about cutaneous calciphylaxis?

A. It is a potentially lethal condition.
B. It exemplifies dystrophic calcification. (Correct Answer)
C. It is characterized by progressive cutaneous vascular calcification.
D. It is seen in patients with chronic renal failure who have increased calcium, phosphate, and parathormone levels.

Explanation: ### Explanation **1. Why Option B is the Correct Answer (The "NOT True" Statement):** Cutaneous calciphylaxis is a form of **metastatic calcification**, not dystrophic calcification [1]. * **Dystrophic calcification** occurs in dead or dying tissues despite **normal** serum calcium and phosphate levels. * **Metastatic calcification** occurs in living tissues due to **deranged** mineral metabolism (hypercalcemia or hyperphosphatemia) [2]. In calciphylaxis, the systemic metabolic environment (high Ca²⁺ × PO₄³⁻ product) drives the deposition of calcium in the walls of small-to-medium-sized dermal and subcutaneous vessels [1]. **2. Analysis of Incorrect Options:** * **Option A:** It is indeed a **potentially lethal** condition. The mortality rate is high (up to 60-80%), primarily due to secondary wound infections and sepsis arising from necrotic skin ulcers. * **Option C:** The hallmark of the disease is **progressive cutaneous vascular calcification**. This leads to intimal fibrosis, thrombosis, and subsequent ischemia (calcific uremic arteriolopathy). * **Option D:** It is most commonly seen in patients with **End-Stage Renal Disease (ESRD)**. Chronic renal failure leads to secondary or tertiary hyperparathyroidism, causing elevated calcium, phosphate, and PTH levels, which are the primary triggers for this condition [2]. **3. NEET-PG High-Yield Pearls:** * **Clinical Presentation:** Presents as painful, violaceous, reticulated plaques (livedo reticularis) that progress to non-healing necrotic ulcers. * **Key Risk Factor:** High **Calcium-Phosphate product** (>55 mg²/dL²). * **Histopathology:** Shows "medial calcification" of small arteries and "fibrointimal hyperplasia." * **Common Sites:** Areas with high adipose tissue (thighs, abdomen). * **Treatment Hint:** Sodium thiosulfate is often used to increase calcium solubility. **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. 76-77. [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. 127-128, 134-135.

Question 1158: A pregnant uterus is an example of which of the following cellular adaptations?

A. Metaplasia
B. Dysplasia
C. Atrophy
D. Hypertrophy (Correct Answer)

Explanation: **Explanation:** The correct answer is **Hypertrophy**. **Why Hypertrophy is Correct:** Hypertrophy refers to an increase in the size of cells, resulting in an increase in the size of the organ [1]. In a pregnant uterus, the massive enlargement is driven by estrogenic stimulation [2]. This process involves both **Hypertrophy** (increase in muscle cell size) and **Hyperplasia** (increase in the number of muscle cells) [1], [2]. However, in the context of standard pathology exams like NEET-PG, the enlargement of the permanent or stable cells of the myometrium is the classic textbook example of **Physiological Hypertrophy** [2]. **Why Other Options are Incorrect:** * **Metaplasia:** This is a reversible change where one adult cell type is replaced by another (e.g., Squamous metaplasia in a smoker's airway). It does not involve organ enlargement. * **Dysplasia:** This refers to disordered growth and maturation of an epithelium (often pre-cancerous). It is a pathological process, not a physiological adaptation to pregnancy. * **Atrophy:** This is the shrinkage in cell size due to loss of cell substance (e.g., the uterus *after* delivery undergoes atrophy/involution). **High-Yield Clinical Pearls for NEET-PG:** * **Pure Hypertrophy:** Occurs in cells with limited replicative capacity, such as **Cardiac Muscle** (e.g., Left Ventricular Hypertrophy in hypertension) and **Skeletal Muscle**. * **Combined Hypertrophy & Hyperplasia:** Occurs in organs with cells capable of replication, such as the **Pregnant Uterus** and **Breast** during lactation [1], [2]. * **Mechanism:** Hypertrophy is mediated by increased production of cellular proteins via the **PI3K/AKT pathway** (physiological) or **G-protein coupled receptors** (pathological) [2]. **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. 85-87. [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.

Question 1159: Which of the following is NOT an antigen-presenting cell?

A. Langerhans cell
B. Dendritic cells
C. T-cells (Correct Answer)
D. B-cells

Explanation: **Explanation:** Antigen-presenting cells (APCs) are specialized immune cells that capture, process, and display foreign antigens on their surface via **MHC Class II molecules** to activate T-lymphocytes [1]. **Why T-cells are the correct answer:** T-cells are the **recipients** of antigen presentation, not the presenters [1]. They possess T-cell receptors (TCRs) that recognize antigens only when they are "presented" by an APC. While T-cells are central to adaptive immunity, they lack the MHC Class II machinery required to function as professional APCs. **Analysis of incorrect options:** * **Dendritic cells (B):** These are the most potent "professional" APCs [1]. They are the only cells capable of activating naive T-cells, making them essential for initiating primary immune responses [3]. * **Langerhans cells (A):** These are specialized dendritic cells found in the **stratum spinosum of the epidermis** [2]. They capture cutaneous antigens and migrate to local lymph nodes to present them to T-cells [2]. * **B-cells (D):** These act as professional APCs by internalizing antigens via surface immunoglobulins and presenting them to Helper T-cells (CD4+), which in turn triggers B-cell differentiation into plasma cells. **NEET-PG High-Yield Pearls:** 1. **Professional APCs:** Include Dendritic cells, Macrophages, and B-cells. All express MHC Class II. 2. **MHC Restriction:** CD4+ T-cells recognize antigens with **MHC II**, while CD8+ T-cells recognize antigens with **MHC I** [4]. 3. **Follicular Dendritic Cells (FDCs):** Found in germinal centers; unlike regular dendritic cells, they trap antigens coated with antibodies/complement and do *not* express MHC II. 4. **Birbeck Granules:** "Tennis-racket" shaped cytoplasmic organelles are a pathognomonic electron microscopy finding in Langerhans cells. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 207-208. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, p. 200. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 204-206. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, p. 240.

Question 1160: What type of necrosis is typically seen in nervous tissue?

A. Coagulative
B. Caseous
C. Fibrinoid
D. Liquefactive (Correct Answer)

Explanation: **Liquefactive necrosis** is the characteristic pattern of cell death in the central nervous system (CNS). [1] This occurs because the brain has a high lipid content and a low amount of supportive connective tissue (stroma). When brain cells die, they release powerful lysosomal enzymes (autolysis) that rapidly digest the tissue into a liquid, viscous mass. [1] In the brain, this process is also facilitated by the action of microglial cells (macrophages of the CNS). Eventually, the liquid is removed, leaving a cystic space. [1] **Analysis of Incorrect Options:** * **Coagulative Necrosis (A):** This is the most common pattern of necrosis in most solid organs (heart, kidney, spleen) following ischemia. It preserves the basic structural outline of the tissue for several days because the injury denatures both structural proteins and enzymes. * **Caseous Necrosis (B):** A "cheese-like" appearance typically seen in Tuberculosis. [2] It is a combination of coagulative and liquefactive necrosis, characterized by a granulomatous inflammatory response. * **Fibrinoid Necrosis (C):** Seen in immune-mediated vascular damage (e.g., Polyarteritis Nodosa) or malignant hypertension, where antigen-antibody complexes and fibrin leak into the vessel walls. **High-Yield Clinical Pearls for NEET-PG:** * **Exception Rule:** While ischemia usually causes coagulative necrosis in most organs, **ischemia in the brain** always causes liquefactive necrosis. [1] * **Other sites for Liquefactive Necrosis:** It is also seen in **abscesses** (focal bacterial or fungal infections) due to the release of enzymes from neutrophils (heterolysis). * **Key Enzyme:** The transformation of the brain into a liquid mass is primarily due to **hydrolytic enzymes**. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1268-1269. [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. 55.

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Cell Injury and Cell Death

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Adaptations of Cellular Growth

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Accumulations and Deposits

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Acute and Chronic Inflammation

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Tissue Repair and Wound Healing

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Hemodynamic Disorders

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Genetic Disorders

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Environmental Pathology

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Nutritional Diseases

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Molecular Basis of Disease

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