Vascular Pathology — MCQs

Vascular Pathology Indian Medical PG Practice Questions and MCQs

Question 161: Which of the following statements regarding atherosclerotic plaque formation is TRUE?

A. It is an acute inflammatory disease of the vascular intima.
B. A characteristic feature is the accumulation of cholesterol esters on the luminal surface of the endothelium.
C. Macrophages bind and phagocytose oxidized LDL to form foam cells. (Correct Answer)
D. They tend to form at branchpoints.

Explanation: **Explanation:** Atherosclerosis is a chronic inflammatory response of the arterial wall to endothelial injury [5]. The correct answer highlights a pivotal step in the "Response to Injury" hypothesis. **Why Option C is Correct:** When the endothelium is damaged, LDL (Low-Density Lipoprotein) enters the tunica intima and undergoes oxidation. Monocytes migrate into the intima, differentiate into macrophages, and utilize **Scavenger Receptors (SR-A and CD36)** to ingest these oxidized LDL particles [1]. Unlike normal LDL receptors, scavenger receptors are not down-regulated by high intracellular cholesterol, leading to the massive accumulation of lipids and the formation of **Foam Cells**, the hallmark of the fatty streak [1], [2]. **Analysis of Incorrect Options:** * **Option A:** Atherosclerosis is a **chronic**, not acute, inflammatory process that develops over decades [5]. * **Option B:** Cholesterol esters accumulate **sub-endothelially** (within the intima), not on the luminal surface [1], [3]. The luminal surface remains the site of blood flow until plaque rupture or significant stenosis occurs [4]. * **Option D:** While this statement is technically a known feature of plaque distribution (hemodynamic stress at branch points) [1], [3], in the context of this specific question and standard pathology examinations, **Option C** describes the fundamental *pathophysiological mechanism* of plaque formation, making it the most definitive answer regarding the "formation" process. **High-Yield NEET-PG Pearls:** * **Most common site:** Abdominal aorta > Coronary arteries > Popliteal arteries > Internal carotid. * **Earliest lesion:** Fatty streak (can be seen in infants) [3]. * **Key Cytokines:** PDGF (Platelet-Derived Growth Factor) and TGF-β are responsible for smooth muscle cell migration and collagen deposition, converting a fatty streak into a stable fibrous plaque [1], [2]. * **Vulnerable Plaque:** Characterized by a large lipid core and a thin fibrous cap [4]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 505-506. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Cardiovascular Disease, pp. 268-270. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 504-505. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 506-507. [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. 200-202.

Question 162: Hypersensitivity vasculitis is typically seen in which of the following vascular structures?

A. Postcapillary venules (Correct Answer)
B. Arterioles
C. Veins
D. Capillaries

Explanation: **Explanation:** **Hypersensitivity Vasculitis** (also known as Leukocytoclastic Vasculitis [3] or Cutaneous Small Vessel Vasculitis) is an immune-mediated inflammation of the small blood vessels. The correct answer is **Postcapillary venules** [1] because these are the primary sites of immune complex deposition (Type III Hypersensitivity). In this condition, circulating antigen-antibody complexes settle in the vessel walls, triggering the complement cascade [2]. This leads to the recruitment of neutrophils [1], which release lysosomal enzymes, causing "leukocytoclasis" (nuclear debris from neutrophils) and fibrinoid necrosis [3]. The postcapillary venule is the preferred site due to its low flow rate and increased permeability, which facilitates the entrapment of these complexes. **Analysis of Incorrect Options:** * **Arterioles:** While involved in some small-vessel vasculitides (like Polyarteritis Nodosa), they are not the characteristic site for hypersensitivity vasculitis. * **Veins:** These are larger vessels. Vasculitis affecting veins specifically is rare and usually associated with systemic conditions like Behçet’s disease. * **Capillaries:** Although often grouped with "small vessels," the classic histopathological hallmark of hypersensitivity vasculitis specifically localizes to the venular side of the microcirculation. **NEET-PG High-Yield Pearls:** * **Clinical Presentation:** Typically presents as **palpable purpura**, most commonly on the lower extremities [3]. * **Histology:** Look for **fibrinoid necrosis** and **leukocytoclasis** (nuclear dust) [1]. * **Common Triggers:** Drugs (Penicillin, Sulfa drugs) and infections (Streptococcus) [3]. * **Henoch-Schönlein Purpura (HSP):** A specific subtype of hypersensitivity vasculitis characterized by **IgA** immune complex deposition. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 518-519. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Cardiovascular Disease, pp. 278-279. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Cardiovascular Disease, pp. 279-280.

Question 163: All of the following are true about arterial thrombosis except?

A. Retrograde growth
B. Lines of Zahn
C. Complete lumen obstruction (Correct Answer)
D. White thrombus

Explanation: **Explanation:** The correct answer is **C (Complete lumen obstruction)** because arterial thrombi are typically **mural** (attached to the wall) and often do not completely occlude the lumen, especially in large arteries like the aorta [5]. In contrast, venous thrombi (phlebothrombosis) are almost always occlusive. **Analysis of Options:** * **Retrograde growth (A):** This is a characteristic feature of arterial thrombi. They grow in a direction opposite to the blood flow (retrograde), extending back toward the heart. Venous thrombi, conversely, grow in the direction of blood flow (anterograde). * **Lines of Zahn (B):** These are pathognomonic macroscopic and microscopic features of thrombi formed in flowing blood (heart or arteries). They consist of alternating pale layers (platelets and fibrin) and dark layers (red blood cells). Their presence confirms that a clot formed **antemortem**. * **White thrombus (D):** Arterial thrombi are known as "white thrombus" because they form in areas of high-speed flow and are primarily composed of a rich meshwork of platelets and fibrin with relatively few trapped red blood cells [2]. Venous thrombi are "red" or "stasis" thrombi due to high RBC content. **High-Yield Clinical Pearls for NEET-PG:** * **Virchow’s Triad:** Endothelial injury (most important for arterial), stasis/turbulent flow, and hypercoagulability [2], [3]. * **Common Sites:** Most common site for arterial thrombosis is the **Coronary arteries**, followed by Cerebral and Femoral arteries [1]. * **Fate of Thrombus:** Propagation, Embolization, Dissolution, or Organization and Recanalization [4]. * **Post-mortem clots:** Distinguished from antemortem thrombi by the absence of Lines of Zahn and a "chicken fat" (supernatant plasma) or "currant jelly" (settled RBCs) appearance. **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] 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. 142-143. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Hemodynamic Disorders, Thromboembolic Disease, and Shock, pp. 135-136. [5] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 508-509.

Question 164: A 50-year-old hypertensive man develops very severe, "tearing" chest pain, which migrates from his upper back to mid-back over the period of an hour. Pathologic examination of a specimen removed from the patient during emergency surgery would MOST likely demonstrate which of the following?

A. Cystic medial degeneration (Correct Answer)
B. Infarction
C. Plasma cells around the vasa vasorum
D. Wrinkling of intima

Explanation: ### Explanation **Correct Answer: A. Cystic Medial Degeneration** The clinical presentation of sudden-onset, "tearing" chest pain radiating to the back in a hypertensive middle-aged man is classic for an **Aortic Dissection** [1], [2]. The migration of pain suggests the dissection is progressing along the length of the aorta [3]. The most common predisposing factor for aortic dissection is **systemic hypertension**, which leads to **Cystic Medial Degeneration (CMD)** [1], [2]. Pathologically, CMD is characterized by the loss of smooth muscle cells, fragmentation of elastic fibers, and the accumulation of mucoid extracellular matrix (proteoglycans) within the tunica media [1]. This weakens the aortic wall, allowing an intimal tear to occur, which then permits blood to force its way into the media, creating a false lumen [1], [3]. **Why the other options are incorrect:** * **B. Infarction:** While dissection can cause secondary ischemia (by compromising branch vessels), the primary pathology of the aortic wall itself is degenerative, not infarctive. * **C. Plasma cells around the vasa vasorum:** This describes **Endarteritis Obliterans**, a hallmark of **Syphilitic (Tertiary) Aortitis** [4]. This typically affects the ascending aorta and leads to aneurysms rather than dissections. * **D. Wrinkling of intima:** Also known as "tree-barking," this is a macroscopic feature of Syphilitic Aortitis caused by scarring and contraction of the media [4]. **NEET-PG High-Yield Pearls:** * **Most common risk factor:** Hypertension (older patients); Marfan Syndrome (younger patients) [2]. * **Classification:** Stanford Type A (involves ascending aorta; surgical emergency) vs. Type B (descending only; medical management) [3]. * **Histology:** Look for "mucoid material" and "elastic fiber fragmentation" on Verhoeff-Van Gieson (VVG) stain [1]. * **Chest X-ray:** Classically shows a **widened mediastinum**. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Cardiovascular Disease, pp. 272-273. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 511-512. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 512-513. [4] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Cardiovascular Disease, pp. 273-274.

Question 165: In primary pulmonary hypertension, what is the basic genetic abnormality?

A. Bone morphogenetic protein receptor II (Correct Answer)
B. Endothelin
C. Homeobox gene
D. PAX-11

Explanation: **Explanation:** **Primary Pulmonary Hypertension (PPH)**, now classified as Idiopathic Pulmonary Arterial Hypertension (IPAH), is characterized by the remodeling of pulmonary arterioles leading to increased vascular resistance [1], [2]. **1. Why Option A is Correct:** The genetic hallmark of familial PPH (seen in ~75% of cases) and many sporadic cases is a germline mutation in the **Bone Morphogenetic Protein Receptor II (BMPR2)** gene [1]. BMPR2 is a member of the TGF-̢ receptor superfamily [2]. Under normal conditions, BMPR2 signaling inhibits the proliferation of vascular smooth muscle cells and promotes apoptosis. A **loss-of-function mutation** leads to uncontrolled proliferation of smooth muscle and endothelial cells, resulting in the characteristic **"Plexiform lesions"** (tufts of capillary formations) seen on histology. **2. Why Other Options are Incorrect:** * **B. Endothelin:** While Endothelin-1 is a potent vasoconstrictor that is *elevated* in pulmonary hypertension and serves as a therapeutic target (e.g., Bosentan), it is a mediator of the disease process, not the underlying genetic cause. * **C. Homeobox gene:** These genes are primarily involved in anatomical development and segmentation during embryogenesis (e.g., HOX genes), not the pathogenesis of PPH. * **D. PAX-11:** PAX genes are transcription factors involved in organogenesis. While PAX-2, 5, and 8 are clinically significant in various tumors, PAX-11 is not associated with vascular pathology. **High-Yield Clinical Pearls for NEET-PG:** * **Histology:** Look for **Plexiform lesions** (pathognomonic for advanced PAH) [3]. * **Inheritance:** BMPR2 mutations follow an **Autosomal Dominant** pattern with low penetrance (only ~20% of carriers develop the disease), suggesting a "second hit" (environmental or genetic) is required [2]. * **Demographics:** Classically affects young adult females. * **Clinical Sign:** Loud P2 (pulmonary component of the second heart sound). **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 324-325. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 706-707. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, p. 707.

Question 166: Polyarteritis nodosa is associated with which of the following?

A. Hypertension (Correct Answer)
B. Trauma
C. Drugs
D. Bronchial asthma

Explanation: **Explanation:** **Polyarteritis Nodosa (PAN)** is a systemic necrotizing vasculitis that typically affects small-to-medium-sized muscular arteries. **Why Hypertension is Correct:** The hallmark of PAN is the involvement of **renal arteries**, which occurs in approximately 80-90% of cases [1]. Unlike many other vasculitides, PAN characteristically **spares the capillaries and glomeruli** (no glomerulonephritis). Instead, it causes transmural inflammation and fibrinoid necrosis of the renal arterial wall [2], leading to luminal narrowing, ischemia, and secondary activation of the Renin-Angiotensin-Aldosterone System (RAAS). This results in **renovascular hypertension**, which is often severe and a major cause of morbidity. **Analysis of Incorrect Options:** * **B. Trauma:** While trauma can cause localized vascular injury, it is not an etiological factor for the systemic autoimmune process of PAN. * **C. Drugs:** Drug-induced vasculitis is more commonly associated with Microscopic Polyangiitis (MPA) or Hypersensitivity Vasculitis, not classic PAN. * **D. Bronchial Asthma:** This is a classic feature of **Churg-Strauss Syndrome** (Eosinophilic Granulomatosis with Polyangiitis). PAN is distinguished by the **absence of pulmonary involvement** and absence of eosinophilia. **High-Yield Clinical Pearls for NEET-PG:** * **Hepatitis B Association:** About 30% of PAN cases are associated with chronic Hepatitis B (HBsAg positive) [1]. * **Morphology:** Characterized by "string of pearls" appearance on angiography due to segmental aneurysms [2]. * **Lesion Age:** PAN shows lesions of **different stages** (acute and healing) coexist in the same vessel [2]. * **ANCA Status:** PAN is typically **ANCA-negative** (unlike MPA or Wegener's) [1]. * **Organ Sparing:** PAN characteristically spares the **lungs**. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 687-688. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 517-518.

Question 167: Hyaline arteriosclerosis is seen in which of the following conditions?

A. Tuberculosis
B. Hypertension (Correct Answer)
C. Syphilis
D. Leprosy

Explanation: **Explanation:** **Hyaline Arteriosclerosis** is a hallmark of small vessel disease characterized by the thickening of arteriolar walls with a homogeneous, pink, "glassy" appearance on H&E stain [1]. 1. **Why Hypertension is Correct:** In **Benign Hypertension**, the chronic hemodynamic pressure forces plasma proteins across the vascular endothelium into the vessel wall [1]. This protein leakage, combined with increased smooth muscle cell matrix synthesis, leads to the characteristic hyaline deposits [2]. This process narrows the lumen, potentially causing downstream ischemia (e.g., Benign Nephrosclerosis in the kidneys) [2], [3]. It is also commonly seen in **Diabetes Mellitus**, where non-enzymatic glycosylation of proteins promotes similar leakage [1]. 2. **Why Other Options are Incorrect:** * **Tuberculosis (A):** Typically involves granulomatous inflammation. While it can cause "Endarteritis Obliterans" (fibrous thickening of the intima) in nearby vessels, it does not cause systemic hyaline arteriosclerosis. * **Syphilis (C):** Tertiary syphilis classically affects the **vasa vasorum** of the aorta (Endarteritis Obliterans), leading to "Tree-barking" of the aorta and aneurysms, rather than hyaline changes in small arterioles [4]. * **Leprosy (D):** Primarily involves peripheral nerves and skin via granulomatous inflammation; it does not have a primary vascular pathology involving hyalinization. **High-Yield Clinical Pearls for NEET-PG:** * **Hyaline vs. Hyperplastic:** Hyaline arteriosclerosis is associated with **Benign Hypertension**, whereas **Hyperplastic Arteriosclerosis** ("onion-skinning") is the hallmark of **Malignant Hypertension** [1]. * **Common Sites:** The kidneys are the most frequently affected organ (Benign Nephrosclerosis) [2], [3]. * **Key Association:** Always remember the "Twin Pillars" of Hyaline Arteriosclerosis: **Old age/Hypertension** and **Diabetes Mellitus** [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 498-499. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 943-945. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 541-542. [4] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Cardiovascular Disease, pp. 273-274.

Question 168: Which of the following is a procoagulant factor produced by endothelial cells?

A. Thrombomodulin
B. Prostacyclin
C. Von Willebrand factor (Correct Answer)
D. von Willebrand factor

Explanation: **Explanation:** Endothelial cells play a dual role in hemostasis, maintaining an antithrombotic surface under physiological conditions but shifting to a **procoagulant** state following injury or activation. **Why Von Willebrand Factor (vWF) is correct:** vWF is a vital procoagulant glycoprotein synthesized by endothelial cells and stored in **Weibel-Palade bodies** [1]. Upon vascular injury, vWF is released and acts as a "molecular glue," binding to exposed subendothelial collagen and the **GpIb receptor** on platelets [2]. This mediates **platelet adhesion**, the first step in primary hemostasis. Additionally, vWF stabilizes Factor VIII in the circulation [1]. **Analysis of Incorrect Options:** * **Thrombomodulin (A):** This is an **anticoagulant** factor. It binds to thrombin and converts it from a procoagulant enzyme into an activator of Protein C, which then inactivates Factors Va and VIIIa [4]. * **Prostacyclin (PGI2) (B):** This is a potent **antithrombotic** mediator. It causes vasodilation and strongly inhibits platelet aggregation by increasing intracellular cAMP levels. * *(Note: Option D is a duplicate of the correct answer).* **High-Yield Clinical Pearls for NEET-PG:** * **Storage:** vWF is stored in **Weibel-Palade bodies** (endothelium) and **Alpha-granules** (platelets) [3]. P-selectin is also stored in Weibel-Palade bodies. * **Deficiency:** von Willebrand Disease (vWD) is the most common inherited bleeding disorder, characterized by a prolonged Bleeding Time (BT) and potentially a prolonged aPTT (due to low Factor VIII). * **Other Procoagulant Factors:** Endothelial cells also produce **Tissue Factor** (in response to cytokines) and **PAI (Plasminogen Activator Inhibitor)** to limit fibrinolysis [4]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, pp. 669-670. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Hemodynamic Disorders, Thromboembolic Disease, and Shock, p. 128. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 581-582. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, pp. 671-672.

Question 169: During a routine physical examination, a 58-year-old white male is found to have a 6-cm pulsatile mass in his abdomen. Angiography reveals a marked dilation of his abdominal aorta distal to his renal arteries. This aneurysm is most likely the result of:

A. Atherosclerosis (Correct Answer)
B. Hypertension
C. Trauma
D. A previous syphilitic infection

Explanation: **Explanation:** The clinical presentation of a **6-cm pulsatile abdominal mass** in an elderly male is a classic description of an **Abdominal Aortic Aneurysm (AAA)**. **1. Why Atherosclerosis is correct:** Atherosclerosis is the most common cause of AAA [1]. The pathogenesis involves the formation of atherosclerotic plaques in the intima, which increases the diffusion distance for oxygen from the lumen to the media. This leads to **ischemic atrophy of the tunica media**, loss of elastic fibers, and subsequent thinning and weakening of the aortic wall [1]. The high pressure within the aorta then causes the weakened wall to dilate. AAAs are characteristically located **distal to the renal arteries** and proximal to the iliac bifurcation [1]. **2. Why other options are incorrect:** * **Hypertension:** While a major risk factor for atherosclerosis and aortic dissection, it is more specifically associated with **Ascending Aortic Aneurysms** rather than abdominal ones [2]. * **Trauma:** Can cause "false aneurysms" (pseudoaneurysms), but these are localized and usually follow a penetrating injury or medical procedure [1], not a chronic 6-cm dilation. * **Syphilitic Infection:** Tertiary syphilis (endarteritis obliterans of vasa vasorum) typically involves the **Ascending Aorta/Aortic Arch**, leading to a "tree-bark" appearance. **High-Yield Clinical Pearls for NEET-PG:** * **Risk Factors:** Smoking is the strongest independent risk factor for AAA (more than hypertension or diabetes) [1]. * **Triad of Rupture:** Sudden severe abdominal/back pain, hypotension, and a pulsatile abdominal mass [3]. * **Screening:** USG is the screening tool of choice; CT is used for surgical planning. * **Surgical Threshold:** Repair is generally indicated if the diameter is **>5.5 cm** in men or **>5.0 cm** in women. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 510-511. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 511-512. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Cardiovascular Disease, pp. 271-272.

Question 170: Postmortem studies of a man shows onion skin thickening of the arteriolar wall, which is characteristic of:

A. Atherosclerosis
B. Medial calcific sclerosis
C. Hyaline arteriolosclerosis
D. Hyperplastic arteriolosclerosis (Correct Answer)

Explanation: ### Explanation **Correct Answer: D. Hyperplastic arteriolosclerosis** **Mechanism:** Hyperplastic arteriolosclerosis is the hallmark of **malignant hypertension** (diastolic BP >120 mmHg) [1]. The rapid and severe increase in blood pressure causes the smooth muscle cells of the arteriolar wall to proliferate and migrate [2]. This results in concentric, laminated thickening of the wall, resembling the layers of an onion (**"onion-skinning"**) [1]. This change is often accompanied by fibrinoid necrosis and luminal narrowing, leading to distal ischemia, particularly in the kidneys (flea-bitten kidney) [1]. **Why other options are incorrect:** * **A. Atherosclerosis:** Affects large and medium-sized elastic and muscular arteries (e.g., aorta, coronary arteries) [2]. It is characterized by intimal plaques (atheromas) containing lipids and foam cells, not concentric arteriolar thickening. * **B. Medial calcific sclerosis (Mönckeberg):** Characterized by ring-like calcifications within the **media** of medium-sized muscular arteries. It does not narrow the lumen and is typically an incidental finding in elderly patients. * **C. Hyaline arteriolosclerosis:** Associated with **benign hypertension** and diabetes mellitus [2]. It shows a homogenous, pink, glassy thickening of the wall due to plasma protein leakage and increased matrix synthesis, lacking the laminated "onion-skin" appearance [2]. **High-Yield Clinical Pearls for NEET-PG:** * **Onion-skinning** is also seen in the spleen in **Systemic Lupus Erythematosus (SLE)** (Periarterial fibrosis). * **Flea-bitten kidney:** Gross appearance of the kidney in malignant hypertension due to pinpoint hemorrhages from ruptured arterioles [1]. * **Hyaline vs. Hyperplastic:** Remember, "Hyaline" = Benign/Chronic; "Hyperplastic" = Malignant/Acute. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, p. 945. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 498-499.

Practice by Chapter

Atherosclerosis

Practice Questions

Hypertensive Vascular Disease

Practice Questions

Aneurysms and Dissection

Practice Questions

Vasculitis

Practice Questions

Venous Disease and Thrombosis

Practice Questions

Vascular Tumors

Practice Questions

Varicose Veins and Lymphatics

Practice Questions

Pathology of Vascular Interventions

Practice Questions

Vascular Diseases in Specific Organs

Practice Questions

Congenital Vascular Anomalies

Practice Questions

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