General Pathology — MCQs

General Pathology Indian Medical PG Practice Questions and MCQs

Question 941: Which of the following is not typically seen in extraglandular Sjögren syndrome?

A. Rheumatoid arthritis
B. Raynaud phenomenon
C. Lymphoma
D. Splenomegaly (Correct Answer)

Explanation: Sjögren syndrome (SS) is a chronic autoimmune disorder characterized by lymphocytic infiltration of exocrine glands (sicca symptoms) and potential extraglandular manifestations. **Why Splenomegaly is the Correct Answer:** While Sjögren syndrome involves systemic inflammation, **splenomegaly is not a typical or diagnostic feature** of the disease. If a patient with SS develops significant splenomegaly or lymphadenopathy, it is often a red flag for the development of B-cell lymphoma rather than a standard manifestation of the syndrome itself. **Analysis of Incorrect Options:** * **A. Rheumatoid Arthritis:** This is the most common condition associated with **Secondary Sjögren syndrome**. Approximately 30-50% of RA patients develop secondary SS [1]. * **B. Raynaud Phenomenon:** This is a well-documented extraglandular manifestation, occurring in about 13-37% of SS patients, often predating the sicca symptoms. * **C. Lymphoma:** Patients with SS have a **40-fold increased risk** of developing Non-Hodgkin Lymphoma (specifically MALT lymphoma). This is a classic high-yield association for exams. **High-Yield Clinical Pearls for NEET-PG:** * **Serology:** Positive for **Anti-Ro (SS-A)** and **Anti-La (SS-B)** antibodies. Anti-Ro is associated with an increased risk of neonatal lupus and congenital heart block. * **Diagnostic Gold Standard:** Lip biopsy showing **focal lymphocytic sialadenitis** (Focus score >1). * **Schirmer Test:** Used to quantify decreased lacrimation (<5mm in 5 minutes). * **Mikulicz Syndrome:** Historical term for bilateral enlargement of salivary and lacrimal glands (now often associated with IgG4-related disease or SS). **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 678-679.

Question 942: Amyloidosis is most commonly secondary to which of the following conditions?

A. Chronic suppuration (Correct Answer)
B. Acute inflammation
C. Cellular necrosis
D. Hyaline degeneration

Explanation: **Explanation:** **Amyloidosis** refers to the extracellular deposition of misfolded proteins in various tissues. The question refers to **Secondary (AA) Amyloidosis**, which occurs as a complication of long-standing inflammatory conditions [1], [3]. **Why Chronic Suppuration is Correct:** Secondary amyloidosis is caused by the deposition of **Amyloid Associated (AA) protein**, which is derived from the precursor **Serum Amyloid A (SAA)** [2]. SAA is an acute-phase reactant synthesized by the liver in response to cytokines (IL-1, IL-6, and TNF-α) [1]. **Chronic suppurative conditions** (e.g., Bronchiectasis, Chronic Osteomyelitis, and Tuberculosis) provide the persistent inflammatory stimulus required for the sustained elevation of SAA, eventually leading to its deposition as amyloid fibrils [3]. **Why the Other Options are Incorrect:** * **Acute Inflammation:** While SAA levels rise in acute inflammation, the stimulus is transient. Amyloid deposition requires a **prolonged, chronic** state of inflammation [3]. * **Cellular Necrosis:** This is a localized process of cell death. While it may trigger a brief inflammatory response, it does not provide the systemic, sustained cytokine drive necessary for AA amyloidosis. * **Hyaline Degeneration:** This is a descriptive histological term for a glassy, pink appearance of tissues (e.g., in vascular walls or old scars). It is a morphological change, not a systemic inflammatory driver of amyloid production. **High-Yield Pearls for NEET-PG:** * **Most common cause of AA Amyloidosis (Global):** Tuberculosis [3]. * **Most common cause of AA Amyloidosis (Developed countries):** Rheumatoid Arthritis [1]. * **Staining:** Congo Red shows **Apple-green birefringence** under polarized light [5]. * **Primary Amyloidosis (AL):** Associated with Plasma Cell Dyscrasias (Multiple Myeloma); involves Light Chains (Kappa/Lambda) [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. 136-140. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 267-268. [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. 195-196. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 266-267. [5] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 268-269.

Question 943: In sarcoidosis, which of the following is histologically true?

A. Epithelioid cells showing caseation
B. Epithelioid cells with no caseation (Correct Answer)
C. Histiocytic cells with caseation
D. Well-differentiated histiocytic cells

Explanation: **Explanation:** The hallmark of **Sarcoidosis** is the presence of **non-caseating granulomas** [1]. A granuloma is a focal collection of inflammatory cells, primarily composed of **epithelioid histiocytes** (activated macrophages that resemble epithelial cells), surrounded by a rim of lymphocytes and occasionally plasma cells [3]. 1. **Why Option B is correct:** In Sarcoidosis, the granulomas are "hard," meaning they lack central necrosis (**non-caseating**) [1]. The epithelioid cells are the defining feature of these granulomas [2]. 2. **Why Option A is incorrect:** Caseation (cheese-like necrosis) is the classic feature of **Tuberculosis**. While Sarcoidosis and TB both form granulomas, the absence of necrosis is the primary histological differentiator for Sarcoidosis [1]. 3. **Why Options C & D are incorrect:** While epithelioid cells are derived from histiocytes, the term "epithelioid cells" is the specific pathological descriptor used for the activated, elongated macrophages found in granulomas [3]. Option C is incorrect because it mentions caseation, and Option D is too vague. **High-Yield Clinical Pearls for NEET-PG:** * **Schaumann Bodies:** Laminated concretions of calcium and proteins found within giant cells in sarcoidosis. * **Asteroid Bodies:** Stellate (star-shaped) inclusions found within the cytoplasm of giant cells. * **Diagnosis of Exclusion:** Sarcoidosis is diagnosed only after ruling out other causes of granulomas (like TB or fungal infections) using AFB stains and GMS stains. * **Bilateral Hilar Lymphadenopathy:** The classic radiological presentation on chest X-ray [1]. * **Elevated Serum ACE levels:** Often used as a marker for disease activity. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 700-701. [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. 198-200. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, p. 109.

Question 944: The process of wound healing includes all of the following except?

A. Coagulation
B. Matrix synthesis
C. Angiogenesis
D. Fibrolysis (Correct Answer)

Explanation: **Explanation:** Wound healing is a complex, orchestrated process traditionally divided into four overlapping phases: **Hemostasis, Inflammation, Proliferation, and Remodeling.** [1] **Why Fibrolysis is the Correct Answer:** **Fibrolysis** (the breakdown of fibrous tissue) is not a standard component of the wound-healing cascade. While *fibrinolysis* (the breakdown of fibrin clots) occurs during the transition from the inflammatory to the proliferative phase, "fibrolysis" is not a recognized physiological step in tissue repair. In fact, the goal of healing is **fibrogenesis** (the synthesis of fibrous tissue) to restore structural integrity. **Analysis of Other Options:** * **Coagulation (Hemostasis):** This is the immediate first phase. Platelets aggregate and a fibrin clot forms to stop bleeding and provide a provisional matrix for migrating cells. [2] * **Matrix Synthesis:** Occurs during the **Proliferative phase**. Fibroblasts migrate to the wound site and synthesize extracellular matrix (ECM) components, primarily Collagen Type III (later replaced by Type I), to provide tensile strength. [1] * **Angiogenesis:** Also part of the **Proliferative phase**. New blood vessels are formed (neovascularization) to supply oxygen and nutrients to the metabolically active regenerating tissue, resulting in the formation of "Granulation Tissue." [2] **High-Yield Clinical Pearls for NEET-PG:** * **Granulation Tissue:** Characterized by the triad of New capillaries (Angiogenesis), Fibroblasts (Matrix synthesis), and Edema. [1] * **Collagen Switch:** In early healing, **Type III Collagen** predominates; during the Remodeling phase, it is replaced by **Type I Collagen** (the strongest type). * **Vitamin C:** Essential for the hydroxylation of proline and lysine residues during collagen synthesis; deficiency leads to poor wound healing (Scurvy). * **Zinc:** A necessary cofactor for **Matrix Metalloproteinases (MMPs)**, which are crucial for the Remodeling phase. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 117-119. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, p. 115.

Question 945: Aging is most probably due to:

A. Non-random mutation in somatic cells
B. Decrease in collagen cross-linking
C. Increase in superoxide dismutase
D. Accumulated free radical injury in tissues (Correct Answer)

Explanation: ### Explanation **Correct Answer: D. Accumulated free radical injury in tissues** Cellular aging is a multifactorial process, but the **Free Radical Theory (Oxidative Stress Theory)** is one of the most widely accepted mechanisms. It posits that aging results from the progressive accumulation of oxidative damage to cellular components (DNA, proteins, and lipids) over time. This damage is primarily caused by **Reactive Oxygen Species (ROS)**, which are byproducts of normal mitochondrial metabolism [1]. As the body’s antioxidant defense mechanisms decline with age, the resulting oxidative stress leads to cellular dysfunction and senescence. **Why the other options are incorrect:** * **A. Non-random mutation in somatic cells:** While DNA damage occurs, aging is generally associated with the accumulation of **random** (stochastic) mutations and metabolic insults rather than a programmed, non-random mutational sequence [3]. * **B. Decrease in collagen cross-linking:** In reality, aging is characterized by an **increase** in the cross-linking of proteins like collagen (often via advanced glycation end-products). This leads to the increased stiffness of tissues and blood vessels seen in the elderly. * **C. Increase in superoxide dismutase (SOD):** SOD is a protective antioxidant enzyme that neutralizes free radicals [1]. An **increase** in SOD would theoretically delay aging; conversely, a **decrease** in antioxidant enzymes is what contributes to the aging process. **High-Yield Clinical Pearls for NEET-PG:** * **Werner Syndrome:** A rare autosomal recessive disorder causing premature aging (progeria) due to a mutation in the **WRN gene** (DNA helicase), leading to defective DNA repair [2]. * **Telomere Attrition:** With each cell division, telomeres shorten. When they reach a critical length, the cell enters **replicative senescence** (the Hayflick limit) [4]. * **Sirtuins:** A family of NAD+-dependent protein deacetylases that promote longevity by increasing metabolic efficiency and DNA repair [2]. * **Caloric Restriction:** The only proven environmental intervention to increase lifespan, likely by reducing IGF-1 signaling and activating sirtuins [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. 100-101. [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. 77-78. [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. 241-242. [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. 243-244.

Question 946: What is the most common site of thrombosis?

A. Vein (Correct Answer)
B. Artery
C. Heart
D. Capillary

Explanation: **Explanation:** The formation of a thrombus is governed by **Virchow’s Triad**: endothelial injury, stasis (or turbulence) of blood flow, and hypercoagulability [3]. **Why Veins are the most common site:** Venous thrombosis (Phlebothrombosis) is significantly more common than arterial thrombosis primarily due to the **hemodynamics of the venous system**. Veins are low-pressure, low-flow vessels where blood moves slowly, especially in the deep veins of the lower extremities [5]. This relative **stasis** allows activated coagulation factors to accumulate and prevents their dilution by fresh blood, making the venous system the most frequent site for thrombus formation. **Analysis of Incorrect Options:** * **B. Artery:** While arterial thrombosis is clinically significant (leading to Myocardial Infarction or Stroke), it is less common than venous thrombosis. It usually occurs at sites of **endothelial injury** caused by atherosclerosis and involves high-flow turbulence rather than stasis [2]. * **C. Heart:** Thrombi in the heart (mural thrombi) typically occur only under specific pathological conditions such as atrial fibrillation, endocarditis, or following a myocardial infarction [4]. * **D. Capillary:** Thrombosis in capillaries is rare and usually associated with microangiopathic hemolytic anemias or disseminated intravascular coagulation (DIC), rather than primary thrombotic events. **NEET-PG High-Yield Pearls:** * **Most common site overall:** Deep veins of the legs (above the knee, such as the popliteal, femoral, and iliac veins) [1]. * **Lines of Zahn:** These are characteristic laminations found in thrombi formed in flowing blood (heart/arteries), helping to distinguish a pre-mortem thrombus from a post-mortem clot. * **Fate of a thrombus:** Propagation, Embolization (most common complication of DVT is Pulmonary Embolism), Dissolution, or Organization/Recanalization. **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. 143-144. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Hemodynamic Disorders, Thromboembolic Disease, and Shock, pp. 132-133. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Hemodynamic Disorders, Thromboembolic Disease, and Shock, pp. 136-137. [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. 145-146. [5] 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. 141-142.

Question 947: Which of the following is NOT included in chronic myeloproliferative disorders?

A. Erythroleukemia (Correct Answer)
B. Polycythemia vera
C. Chronic myeloid leukemia (CML)
D. Essential thrombocytosis

Explanation: **Explanation:** Chronic Myeloproliferative Neoplasms (MPNs) are a group of clonal hematopoietic stem cell disorders characterized by the proliferation of one or more myeloid lineages (granulocytes, erythrocytes, or megakaryocytes) with effective maturation, leading to increased peripheral blood counts [1]. **Why Erythroleukemia is the Correct Answer:** Erythroleukemia (formerly FAB M6) is a subtype of **Acute Myeloid Leukemia (AML)**. Unlike MPNs, which are characterized by mature cell proliferation, AML involves a "maturation arrest" resulting in the accumulation of immature blasts (≥20% in bone marrow/blood). It is an acute, aggressive malignancy rather than a chronic myeloproliferative process. **Analysis of Incorrect Options:** * **Chronic Myeloid Leukemia (CML):** The classic MPN characterized by the Philadelphia chromosome $t(9;22)$ and the $BCR-ABL1$ fusion gene, leading to predominant proliferation of the granulocytic line [1]. * **Polycythemia Vera (PV):** An MPN characterized by autonomous erythropoiesis, resulting in increased red cell mass. Over 95% of cases are associated with the $JAK2\ V617F$ mutation [2]. * **Essential Thrombocytosis (ET):** An MPN involving primary proliferation of megakaryocytes and persistent thrombocytosis [1]. Common mutations include $JAK2$, $CALR$, and $MPL$ [1]. **NEET-PG High-Yield Pearls:** 1. **WHO Classification:** The four "classic" MPNs are CML, PV, ET, and Primary Myelofibrosis (PMF) [1]. 2. **The JAK2 Connection:** $JAK2\ V617F$ mutation is found in almost all PV cases and approximately 50-60% of ET and PMF cases, but it is typically absent in CML [1]. 3. **Transformation:** All chronic MPNs carry a risk of transforming into **Acute Myeloid Leukemia** (Blast Crisis). 4. **Splenomegaly:** Massive splenomegaly is a hallmark of CML and Primary Myelofibrosis [1]. **References:** [1] 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, p. 624. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 614-615.

Question 948: Which one of the listed statements is the best histologic definition of an abscess?

A. A circumscribed collection of neutrophils with necrotic cellular debris (Correct Answer)
B. A localized defect that results from the sloughing of necrotic inflammatory tissue from the surface of an organ
C. A localized proliferation of fibroblasts and small blood vessels
D. An aggregate of two or more activated macrophages

Explanation: **Explanation:** **1. Why Option A is correct:** An **abscess** is a localized collection of purulent inflammatory tissue (pus) caused by suppuration buried in a tissue, an organ, or a confined space. Histologically, it is characterized by a central mass of **necrotic leukocytes (neutrophils)** and tissue cells, surrounded by a zone of preserved neutrophils [1]. Over time, this may be walled off by connective tissue (fibrosis). The hallmark of an abscess is **liquefactive necrosis**, typically triggered by pyogenic bacteria (e.g., *Staphylococcus aureus*) [2]. **2. Why the other options are incorrect:** * **Option B:** This describes an **Ulcer**. An ulcer is a local defect or excavation of the surface of an organ or tissue produced by the sloughing of inflamed necrotic tissue. * **Option C:** This describes **Granulation Tissue**. This is a hallmark of the proliferative phase of wound healing and chronic inflammation, consisting of new capillaries (angiogenesis) and fibroblasts. * **Option D:** This describes a **Granuloma** (specifically a microscopic aggregate of epithelioid histiocytes) [2]. Granulomatous inflammation is a form of chronic inflammation, not acute suppurative inflammation. **3. NEET-PG High-Yield Pearls:** * **Primary Cell Type:** Neutrophils are the dominant cells in an abscess [1]. * **Type of Necrosis:** Always **Liquefactive Necrosis** (due to the release of lysosomal enzymes from neutrophils). * **Commonest Organism:** *Staphylococcus aureus* is the most common cause of "cold" and "hot" abscesses in various tissues. * **Fate:** If not drained ("Ubi pus, ibi evacua"), an abscess may undergo organization and replacement by a scar [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. 192-193. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, p. 360. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 101-103.

Question 949: The amyloid protein in primary systemic amyloidosis belongs to which of the following classes of fibril proteins?

A. AA protein
B. AL protein (Correct Answer)
C. Amyloid beta precursor protein
D. Beta 2 microglobulin

Explanation: **Explanation:** **Correct Answer: B. AL protein** Amyloidosis is a disorder of protein misfolding where insoluble fibrillar proteins deposit in the extracellular space [2]. **Primary systemic amyloidosis** is associated with plasma cell dyscrasias (such as Multiple Myeloma) [1]. In this condition, plasma cells produce excessive amounts of monoclonal immunoglobulin light chains [5]. These light chains (or their fragments) undergo partial proteolysis to form **AL (Amyloid Light chain) protein** fibrils [4]. **Analysis of Incorrect Options:** * **A. AA protein:** This is "Amyloid Associated" protein derived from Serum Amyloid A (SAA), an acute-phase reactant [3]. It is seen in **Secondary (Reactive) Amyloidosis**, which occurs due to chronic inflammatory conditions like Rheumatoid Arthritis, Tuberculosis, or Osteomyelitis. * **C. Amyloid beta precursor protein (Aβ):** This protein is derived from the Amyloid Precursor Protein (APP). It deposits in the brain parenchyma and blood vessels in patients with **Alzheimer’s disease**. * **D. Beta 2 microglobulin (Aβ2M):** This is a component of MHC Class I molecules. It cannot be filtered by standard dialysis membranes, leading to **Hemodialysis-associated amyloidosis**, typically presenting as carpal tunnel syndrome or joint involvement. **High-Yield Clinical Pearls for NEET-PG:** * **Staining:** All amyloid types show **Apple-green birefringence** under polarized light when stained with **Congo Red** [5]. * **Morphology:** On Electron Microscopy, amyloid appears as **7.5–10 nm non-branching fibrils** in a cross-beta pleated sheet configuration [5]. * **Transthyretin (ATTR):** Associated with Senile Systemic Amyloidosis (Normal TTR) and Familial Amyloid Polyneuropathies (Mutated TTR). * **Calcitonin (A-Cal):** Associated with Medullary Carcinoma of the Thyroid. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 266-267. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 264-266. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 267-268. [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. 135-136. [5] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 533-534.

Question 950: Which of the following is NOT true about graft versus host reaction?

A. Lymphocytic infiltration of portal tract
B. Bile duct damage
C. Intrahepatic cholestasis
D. None of the above (Correct Answer)

Explanation: **Explanation:** Graft-versus-host disease (GVHD) occurs when immunocompetent donor T-cells recognize the recipient's (host) HLA antigens as foreign and initiate an immune attack [1]. This is most common following allogeneic bone marrow or hematopoietic stem cell transplantation [1]. **Why "None of the above" is correct:** In the liver, GVHD primarily targets the **epithelial cells of the bile ducts** and the **endothelium of the portal vein branches**. All three listed options (A, B, and C) are classic pathological hallmarks of hepatic GVHD: * **Lymphocytic infiltration of portal tracts:** Donor T-cells infiltrate the portal areas to attack host cells [1]. * **Bile duct damage:** This is the most characteristic feature, often manifesting as nuclear pleomorphism, vacuolation, and eventual destruction (ductopenia). * **Intrahepatic cholestasis:** As a consequence of bile duct damage and inflammation, bile flow is obstructed, leading to clinical jaundice and elevated alkaline phosphatase. Since all three statements (A, B, and C) are **true** descriptions of the pathology of GVHD, the correct answer is "None of the above." **Clinical Pearls for NEET-PG:** * **Target Organs:** The primary targets of GVHD are the **Skin** (rash/dermatitis), **Liver** (cholestasis), and **GI Tract** (diarrhea) [1]. * **Acute vs. Chronic:** Acute GVHD typically occurs within 100 days; Chronic GVHD occurs after 100 days and often mimics autoimmune diseases like Scleroderma or Sicca syndrome. * **Prerequisite:** For GVHD to occur, the graft must contain immunologically competent cells, and the recipient must be immunocompromised (Billingham’s criteria). * **Prevention:** Depletion of donor T-cells before transfusion can prevent GVHD but may increase the risk of graft failure or leukemia recurrence. **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. 182-183.

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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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