Inflammation and Repair — MCQs

Inflammation and Repair Indian Medical PG Practice Questions and MCQs

Question 121: Necrotizing epithelioid cell granulomas are seen in all, except?

A. Tuberculosis
B. Wegener's granulomatosis
C. Cat's Scratch disease
D. Leprosy (Correct Answer)

Explanation: ### Explanation The core of this question lies in distinguishing between **necrotizing (caseating)** and **non-necrotizing** granulomas. **Why Leprosy is the Correct Answer:** In Leprosy (*Mycobacterium leprae*), the type of granuloma depends on the host's immune response [1]. In **Tuberculoid Leprosy**, you see well-formed **non-caseating (non-necrotizing)** epithelioid cell granulomas [2]. In Lepromatous Leprosy, granulomas are poorly formed and consist of foamy macrophages (Virchow cells) packed with bacilli, but central necrosis is typically absent [2]. Therefore, it does not classically present with necrotizing epithelioid granulomas. **Analysis of Incorrect Options:** * **Tuberculosis (TB):** The prototype of necrotizing granulomatous inflammation. It characteristically shows **caseating necrosis** (cheese-like) at the center of epithelioid granulomas due to the delayed-type hypersensitivity response to *M. tuberculosis*. * **Wegener’s Granulomatosis (GPA):** This is a small-vessel vasculitis characterized by a "triad" of involvement. It classically features **geographic necrosis** (irregular, jagged areas of necrosis) surrounded by palisading granulomas. * **Cat Scratch Disease:** Caused by *Bartonella henselae*, it typically presents with lymphadenopathy showing **stellate (star-shaped) necrotizing granulomas** with central neutrophils (microabscesses). **NEET-PG High-Yield Pearls:** 1. **Non-caseating Granulomas:** Think Sarcoidosis (classic), Tuberculoid Leprosy, Crohn’s disease, and Berylliosis. 2. **Stellate Necrosis:** Characteristic of Cat Scratch Disease and Lymphogranuloma Venereum (LGV). 3. **Gummatous Necrosis:** Specific to Tertiary Syphilis. 4. **Schistosoma haematobium:** Causes granulomas in the urinary bladder with terminal-spined eggs. 5. **Langhans Giant Cells:** Characterized by peripheral "horseshoe" arrangement of nuclei; commonly seen in TB and Leprosy. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Disorders Involving Inflammatory And Haemopoietic Cells, pp. 638-639. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 385-386.

Question 122: What is the correct sequence of cellular appearance in wound healing?

A. Macrophage, Platelet, Neutrophils, Fibroblast
B. Neutrophils, Macrophages, Platelet, Fibroblast
C. Platelet, Neutrophils, Macrophages, Fibroblast (Correct Answer)
D. Platelet, Macrophages, Neutrophils, Fibroblast

Explanation: ### Explanation: Sequence of Cellular Events in Wound Healing Wound healing is a highly orchestrated process divided into four overlapping phases: **Hemostasis, Inflammation, Proliferation, and Remodeling.** The sequence of cellular arrival is dictated by the specific requirements of each phase [1], [2]. **1. Why Option C is Correct:** * **Platelets (Seconds to Minutes):** Immediately following injury, platelets aggregate to form a hemostatic plug and release growth factors (like PDGF and TGF-β) that act as chemoattractants for subsequent cells [2]. * **Neutrophils (24–48 Hours):** These are the first inflammatory cells to arrive [1]. Their primary role is to clear bacteria and debris via phagocytosis and the release of reactive oxygen species. * **Macrophages (48–72 Hours):** These are the "master orchestrators." They replace neutrophils, continue phagocytosis, and secrete cytokines that transition the wound from the inflammatory phase to the proliferative phase [1], [3]. * **Fibroblasts (Days 3–7):** Stimulated by macrophage-derived factors, fibroblasts migrate to the site to synthesize collagen and extracellular matrix, forming granulation tissue [3], [4]. **2. Why Other Options are Incorrect:** * **Options A & B:** Incorrect because they place inflammatory cells before platelets. Without initial platelet activation and clot formation, the chemical signals required to recruit leukocytes would be absent [2]. * **Option D:** Incorrect because it suggests macrophages arrive before neutrophils. In the standard acute inflammatory response, the smaller, more numerous neutrophils always extravasate before the larger monocytes/macrophages [1]. **3. NEET-PG High-Yield Pearls:** * **The "Master Cell":** Macrophages are considered the most essential cell for successful wound healing due to their regulatory role [3]. * **Type of Collagen:** In early granulation tissue, **Type III Collagen** predominates; it is later replaced by **Type I Collagen** (stronger) during the remodeling phase. * **Tensile Strength:** At the end of 1 week (suture removal), wound strength is ~10%. It reaches a maximum of ~70-80% by 3 months. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, p. 89. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 117-119. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, p. 115. [4] 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. 105-106.

Question 123: Which of the following are acute phase reactants in acute inflammation?

A. Albumin
B. Fibrinogen
C. Haptoglobin
D. All of the above (Correct Answer)

Explanation: **Explanation:** Acute Phase Reactants (APRs) are plasma proteins whose concentrations change by at least 25% in response to inflammatory stimuli (IL-1, IL-6, and TNF) [1]. They are synthesized primarily in the liver. **1. Why the answer is "All of the above":** APRs are categorized into two groups: * **Positive APRs:** These **increase** during inflammation to assist the immune system. **Fibrinogen** (Option B) increases to aid in clot formation and is responsible for the elevated ESR seen in inflammation. **Haptoglobin** (Option C) increases to bind free hemoglobin, preventing oxidative tissue damage and depriving bacteria of iron. * **Negative APRs:** These **decrease** during inflammation to conserve amino acids for the synthesis of positive APRs. **Albumin** (Option A) is the classic example of a negative APR. Since the question asks which of the following *are* acute phase reactants (without specifying positive or negative), all three options qualify. **2. Analysis of Options:** * **Albumin:** Decreases (Negative APR). * **Fibrinogen:** Increases (Positive APR); causes "rouleaux" formation of RBCs. * **Haptoglobin:** Increases (Positive APR); also an antioxidant. **Clinical Pearls for NEET-PG:** * **C-Reactive Protein (CRP):** The most sensitive and commonly used clinical marker for acute inflammation. It acts as an opsonin. * **Ferritin:** A positive APR; its elevation during inflammation can mask an underlying iron deficiency (Anemia of Chronic Disease). * **Procalcitonin:** A specific marker used to distinguish bacterial infections from viral or non-infectious inflammation. * **Transthyretin (Pre-albumin) and Transferrin:** Other important **negative** APRs to remember [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 83-99.

Question 124: All of the following are false regarding vascular leakage in acute inflammation, except:

A. Chemical mediators such as histamine play a role in delayed vascular leakage.
B. A hallmark of acute inflammation is increased permeability in the post-capillary venules. (Correct Answer)
C. Transcytosis is not a contributing factor to vascular leakage.
D. In most cases, vascular leakage starts several hours after injury.

Explanation: Vascular leakage (increased vascular permeability) is the hallmark of acute inflammation, leading to the escape of protein-rich fluid (exudate) into the extravascular tissue, resulting in edema. [1] **Why Option B is Correct:** The most common mechanism of vascular leakage is **endothelial cell contraction**, which leads to the formation of intercellular gaps. [1] This process occurs **predominantly in the post-capillary venules**. [1] This is because the density of receptors for inflammatory mediators (like histamine and leukotrienes) is highest in these specific vessels compared to capillaries or arterioles. [2] **Analysis of Incorrect Options:** * **Option A:** Chemical mediators like **histamine, bradykinin, and leukotrienes** are responsible for the **immediate transient response**, which occurs within minutes and lasts for about 15–30 minutes. [1] They do not typically mediate delayed leakage. * **Option C:** **Transcytosis** (increased transport of fluids and proteins through endothelial cells via intracellular channels) **is** a contributing factor, often stimulated by Vascular Endothelial Growth Factor (VEGF). * **Option D:** In most cases (the immediate transient response), vascular leakage starts **immediately** after injury. [1] A "delayed prolonged response" (starting after 2–12 hours) occurs only in specific injuries like mild thermal burns or UV radiation. [1] **High-Yield NEET-PG Pearls:** * **Most common mechanism:** Endothelial cell contraction (Immediate transient response). * **Most common site:** Post-capillary venules. [1] * **Direct Endothelial Injury:** Affects all levels of microcirculation (venules, capillaries, and arterioles) and is seen in severe burns or lytic bacterial infections. [1] * **Starling’s Hypothesis:** In inflammation, the increase in osmotic pressure of the interstitial fluid (due to protein leakage) and the increase in hydrostatic pressure (due to vasodilation) both favor edema. [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. 187-188. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, p. 101. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 84-85.

Question 125: Tuberculosis is typically associated with which type of necrosis?

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

Explanation: **Explanation:** **Caseous necrosis** is the hallmark of tuberculosis (TB) [1], [2]. The term "caseous" (cheese-like) refers to the friable, yellow-white macroscopic appearance of the necrotic area [2]. Microscopically, it is characterized by a complete loss of cellular architecture, appearing as amorphous, eosinophilic, granular debris [1]. This occurs due to a combination of coagulative and liquefactive processes, typically enclosed within a granulomatous inflammatory border (Ghon complex). **Analysis of Incorrect Options:** * **Coagulative necrosis:** The most common pattern, seen in **ischemic infarction** of all solid organs except the brain. It preserves the basic structural outline of the dead tissue for several days. * **Liquefactive necrosis:** Characterized by the digestion of dead cells into a liquid viscous mass. It is seen in **focal bacterial/fungal infections** (abscesses) and **hypoxic death of cells within the CNS (brain infarcts)**. * **Fibrinoid necrosis:** Usually seen in **immune-mediated vascular damage** (e.g., Polyarteritis Nodosa, Malignant Hypertension). It involves the deposition of immune complexes and fibrin in arterial walls, appearing bright pink and "smudgy" on H&E stain. **NEET-PG High-Yield Pearls:** * **Granuloma Composition:** TB granulomas are "caseating," consisting of epithelioid histiocytes, Langhans giant cells (peripheral nuclei in horseshoe pattern), and a central zone of caseous necrosis [1]. * **Exception:** In immunocompromised patients (e.g., advanced HIV), TB may present with **non-caseating** granulomas due to a weak T-cell response [1]. * **Fat Necrosis:** Another specific type, seen in **Acute Pancreatitis** (enzymatic) or breast trauma, characterized by "chalky white" calcium deposits (saponification) [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 383-384. [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.

Question 126: Serotonin, a mediator of inflammation, is secreted/released by which of the following cells?

A. Leukocytes
B. Endothelial cells
C. Mast cells
D. Platelets (Correct Answer)

Explanation: **Explanation:** **Correct Answer: D. Platelets** Serotonin (5-hydroxytryptamine) is a preformed vasoactive amine that acts as a potent mediator of inflammation [1]. Its primary role in the inflammatory response is to cause vasodilation and increased vascular permeability [2]. In humans, serotonin is primarily stored in the **dense granules (delta granules) of platelets** [1]. It is released during platelet aggregation, which occurs when platelets come into contact with collagen, thrombin, or ADP following tissue injury. **Analysis of Incorrect Options:** * **A. Leukocytes:** While leukocytes (neutrophils and macrophages) produce many mediators like cytokines, leukotrienes, and prostaglandins, they are not a primary source of serotonin. * **B. Endothelial cells:** These cells respond to serotonin and produce other mediators like Nitric Oxide (NO) and Endothelin, but they do not store or secrete serotonin [4]. * **C. Mast cells:** In rodents, mast cells contain serotonin; however, **in humans, mast cells contain Histamine**, not serotonin [1]. This is a common point of confusion in pathology. **High-Yield Clinical Pearls for NEET-PG:** * **Vasoactive Amines:** Histamine and Serotonin are the first mediators to be released during the early phase of acute inflammation [3]. * **Source Distinction:** Remember the "H-M" and "S-P" rule for humans: **H**istamine comes from **M**ast cells; **S**erotonin comes from **P**latelets [1]. * **Other Sources:** Outside of the inflammatory response, serotonin is also found in the enterochromaffin cells of the gastrointestinal tract and the central nervous system [1]. * **Platelet Granules:** * **Alpha granules:** Contain P-selectin, Fibrinogen, and Fibronectin. * **Dense (Delta) granules:** Contain **S**erotonin, **A**DP/ATP, and **C**alcium (Mnemonic: **SAC**). **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 94-95. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, p. 101. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 93-94. [4] 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. 187-188.

Question 127: In a granuloma, epithelioid cells and giant cells are derived from which cell type?

A. T lymphocytes
B. Monocyte-macrophages (Correct Answer)
C. B lymphocytes
D. Mast cells

Explanation: **Explanation:** A **granuloma** is a distinctive pattern of chronic inflammation characterized by a localized collection of **epithelioid histiocytes**. The core mechanism involves a Type IV hypersensitivity reaction where persistent antigens trigger a cell-mediated immune response [1][4]. **Why Monocyte-macrophages is correct:** Epithelioid cells are essentially **activated macrophages** that have undergone a morphological change [1]. Under the influence of **Interferon-gamma (IFN-γ)**—secreted by Th1 cells—macrophages enlarge, develop abundant pink granular cytoplasm, and resemble epithelial cells (hence "epithelioid") [1]. When these epithelioid cells fuse together, they form **multinucleated giant cells** (e.g., Langhans giant cells in TB or Foreign body giant cells) [1][2]. Therefore, both epithelioid and giant cells are derivatives of the monocyte-macrophage lineage. **Why other options are incorrect:** * **T lymphocytes (A):** While Th1 cells are crucial for *activating* macrophages via IFN-γ, they do not transform into epithelioid cells themselves [1]. They typically form a "cuff" or rim around the periphery of the granuloma [1]. * **B lymphocytes (C):** These cells differentiate into plasma cells to produce antibodies (humoral immunity) and are not the primary structural components of a granuloma [3]. * **Mast cells (D):** These are involved in Type I hypersensitivity (allergy) and acute inflammation; they do not contribute to the formation of epithelioid or giant cells. **High-Yield NEET-PG Pearls:** * **Defining feature of a granuloma:** Presence of epithelioid cells (not just giant cells) [1]. * **Langhans Giant Cell:** Nuclei arranged in a "horseshoe" pattern at the periphery (classic for Tuberculosis) [1]. * **Foreign Body Giant Cell:** Nuclei scattered randomly throughout the cytoplasm [2]. * **Key Cytokine:** IFN-γ is the most important cytokine for granuloma formation and macrophage activation [1][4]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, p. 109. [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. 196-197. [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. 197-199. [4] 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. 173-174.

Question 128: Which of the following is an exogenous pyrogen?

A. TNF-a
B. Lipopolysaccharide (Correct Answer)
C. Neurotropic factor
D. IL-6

Explanation: ### Explanation **Concept Overview:** Pyrogens are substances that induce fever by acting on the hypothalamus to increase the thermoregulatory set point. They are classified into two categories: **Exogenous** (originating outside the body) and **Endogenous** (produced by the body’s own immune cells). **Why Lipopolysaccharide (LPS) is Correct:** Lipopolysaccharide (LPS), also known as **endotoxin**, is a structural component of the outer membrane of **Gram-negative bacteria** [1]. Since it originates from a microbial source outside the human host, it is a classic **exogenous pyrogen**. LPS works by stimulating macrophages and monocytes to release endogenous pyrogenic cytokines [1]. **Analysis of Incorrect Options:** * **A. TNF-̑ (Tumor Necrosis Factor-alpha):** This is an **endogenous pyrogen**. It is a cytokine produced primarily by activated macrophages in response to exogenous stimuli. * **D. IL-6 (Interleukin-6):** This is also an **endogenous pyrogen**. Along with IL-1 and TNF, IL-6 travels through the bloodstream to the anterior hypothalamus to induce prostaglandin synthesis. * **C. Neurotropic factor:** These are proteins (like BDNF) responsible for the growth and survival of neurons; they do not play a primary role in the pathogenesis of fever. **High-Yield Clinical Pearls for NEET-PG:** * **The "Final Common Pathway":** Both exogenous and endogenous pyrogens ultimately lead to the release of **Prostaglandin E2 (PGE2)** in the preoptic area of the hypothalamus. * **Mechanism of Antipyretics:** NSAIDs and Aspirin reduce fever by inhibiting the enzyme **Cyclooxygenase (COX)**, thereby blocking the synthesis of PGE2. * **Key Endogenous Pyrogens:** Remember the triad: **IL-1, TNF-̑, and IL-6**. Among these, IL-1 is often considered the most potent [1]. **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. 62-64.

Question 129: In the cyclooxygenase (COX) pathway of arachidonic acid metabolism, which of the following products promotes platelet aggregation and vasoconstriction?

A. C5a
B. Thromboxane A2 (Correct Answer)
C. Leukotriene B4
D. C1 activators

Explanation: The correct answer is **Thromboxane A2 (TXA2)**. Arachidonic acid is released from membrane phospholipids by phospholipase A2 [1] and metabolized via two major pathways: the Cyclooxygenase (COX) pathway and the Lipoxygenase (LOX) pathway. 1. **Why Thromboxane A2 is correct:** TXA2 is synthesized primarily in platelets via the COX pathway. It is a potent **vasoconstrictor** and a powerful **inducer of platelet aggregation** [1]. It acts in physiological antagonism to Prostacyclin (PGI2), which is a vasodilator and inhibitor of aggregation. The balance between TXA2 and PGI2 is critical for maintaining vascular homeostasis. 2. **Why other options are incorrect:** * **C5a:** This is a component of the Complement System (Anaphylatoxin). Its primary roles are chemotaxis for neutrophils and increasing vascular permeability [1]; it is not a product of the COX pathway. * **Leukotriene B4 (LTB4):** While derived from arachidonic acid, it is a product of the **Lipoxygenase (LOX) pathway**. It is a potent chemotactic agent for neutrophils but does not cause platelet aggregation [1]. * **C1 activators:** These are proteins involved in the initiation of the Classical Complement pathway, unrelated to arachidonic acid metabolism. **NEET-PG High-Yield Pearls:** * **Aspirin's Mechanism:** Low-dose aspirin irreversibly inhibits COX-1, shifting the balance toward PGI2 (antithrombotic) by inhibiting TXA2 synthesis in platelets (which cannot regenerate the enzyme) [1]. * **Chemotaxis Mnemonic:** "Big B" (**LTB4**), **C5a**, and **IL-8** are the primary "attractants" for neutrophils. * **Vasodilation:** Prostaglandins **PGI2, PGE1, PGE2, and PGD2** are primarily vasodilators [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 95-96.

Question 130: The healing of an extraction socket where flaps are approximated occurs by which type of intention?

A. Primary intention (Correct Answer)
B. Secondary intention
C. Tertiary intention
D. Any of the above

Explanation: **Explanation:** The healing of a wound is categorized based on the nature of the injury and the method of closure. **1. Why Primary Intention is Correct:** Healing by **Primary Intention (First Intention)** occurs when wound edges are clean, uninfected, and closely approximated (brought together) using sutures, staples, or flaps [1]. In the case of an extraction socket where flaps are used to close the gap, the distance for keratinocyte migration is minimized, and there is minimal tissue loss. This results in rapid healing with very little granulation tissue formation and a thin, linear scar. **2. Why the other options are incorrect:** * **Secondary Intention:** This occurs when there is extensive tissue loss, infection, or when the wound edges are left open (e.g., a standard extraction socket left to heal on its own) [2]. It involves significant granulation tissue formation, wound contraction (mediated by myofibroblasts), and a larger scar [2]. * **Tertiary Intention (Delayed Primary Closure):** This is used for contaminated wounds. The wound is initially left open to manage infection and is surgically closed only after it is clean. **High-Yield Clinical Pearls for NEET-PG:** * **Key Difference:** Primary intention involves "approximation"; Secondary intention involves "contraction." * **Myofibroblasts:** These are the hallmark of secondary intention, responsible for wound contraction [3]. * **Tensile Strength:** At the end of 1 week (suture removal), strength is ~10% [4]. It reaches ~70-80% by 3 months but **never** returns to 100% of original strength [4]. * **Type III vs. Type I Collagen:** In early healing, Type III collagen is predominant; it is later replaced by Type I collagen (the strongest type) during remodeling [4]. **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. 106-107. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, p. 119. [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. 105-106. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 119-121.

Practice by Chapter

Acute Inflammation: Vascular Events

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Acute Inflammation: Cellular Events

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Chemical Mediators of Inflammation

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Chronic Inflammation

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Granulomatous Inflammation

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Systemic Effects of Inflammation

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Wound Healing

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Tissue Regeneration

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Fibrosis and Repair

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Resolution of Inflammation

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