Vascular Pathology — MCQs

A 56-year-old woman diagnosed with cancer in her left breast underwent a mastectomy with axillary lymph node dissection. Postoperatively, she develops marked swelling of the left arm that has persisted for 6 months. On physical examination, her temperature is 36.9°C. Her left arm is not tender or erythematous, and it is not painful with movement or to touch, but it is enlarged with a doughy consistency. Which of the following is the most likely mechanism for these findings?

Q16Medium

A woman has septic abortion with vegetation on the tricuspid valve. Where are septic emboli most likely to travel?

Q17Medium

Sudden death, right-sided heart failure (cor pulmonale or cardiovascular collapse) occurs when?

Q18Medium

An elderly female presents with fever, headache, and diplopia. Biopsy of the artery revealed panarteritis. What is the most probable diagnosis?

Q19Medium

A 75-year-old man has experienced headaches for the past 2 months. On physical examination, his vital signs are temperature, 37°C; pulse, 68/min; respirations, 15/min; and blood pressure, 130/85 mm Hg. His right temporal artery is prominent, palpable, and painful to the touch. His heart rate is regular, and there are no murmurs. His erythrocyte sedimentation rate is 100 mm/hr. A temporal artery biopsy is performed, and the segment of the temporal artery excised is grossly thickened and shows focal microscopic granulomatous inflammation. He responds well to corticosteroid therapy. Which of the following complications of this disease is most likely to occur in untreated patients?

Q20Easy

What is the most common cause of thrombotic pulmonary embolism?

Vascular Pathology Indian Medical PG Practice Questions and MCQs

Question 11: Accumulation of which type of lipoprotein is characteristic of atherosclerosis?

A. Oxidised LDL (Correct Answer)
B. HDL
C. VLDL
D. Glycerides

Explanation: **Explanation:** The pathogenesis of atherosclerosis is best described by the **"Response to Injury" hypothesis** [5]. The process begins with chronic endothelial injury, which increases vascular permeability and allows **Low-Density Lipoprotein (LDL)** to accumulate within the tunica intima [1]. **Why Oxidized LDL is correct:** Native LDL itself is not highly atherogenic. However, once trapped in the intima, LDL undergoes oxidation by free radicals generated by endothelial cells or macrophages [1]. **Oxidized LDL (ox-LDL)** is the key pathological driver because: 1. It is chemotactic for monocytes. 2. It is ingested by macrophages via **scavenger receptors** (CD36 and SR-A). Unlike the regulated LDL receptor, scavenger receptors do not downregulate, leading to the massive accumulation of cholesterol and the formation of **Foam Cells**, the hallmark of the fatty streak [3]. 3. It is cytotoxic to endothelial cells and smooth muscle cells. **Analysis of Incorrect Options:** * **HDL (High-Density Lipoprotein):** Known as "good cholesterol," it facilitates reverse cholesterol transport (moving cholesterol from tissues back to the liver) and is actually protective against atherosclerosis [2], [5]. * **VLDL (Very-Low-Density Lipoprotein):** While VLDL remnants can contribute to plaque, they are not the primary characteristic lipoprotein involved in the initiation of the fatty streak compared to ox-LDL. * **Glycerides (Triglycerides):** While elevated triglycerides are a risk factor, they are not the specific lipoprotein species that accumulates within macrophages to form foam cells. **NEET-PG High-Yield Pearls:** * **First visible lesion:** Fatty streak (can be seen in aortas of children <10 years) [4]. * **Most common site:** Lower abdominal aorta > Coronary arteries > Popliteal arteries > Internal carotid. * **Key Cell Types:** Macrophages and Smooth Muscle Cells (SMCs). SMCs migrate from the media to the intima and produce extracellular matrix, converting a fatty streak into a **fibrofatty plaque** [3]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 503-504. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 500-501. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 505-506. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 504-505. [5] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Cardiovascular Disease, pp. 270-271.

Question 12: Which of the following blood vessels is most commonly affected by atherosclerosis?

A. Popliteal artery
B. Thoracic aorta
C. Abdominal aorta (Correct Answer)
D. Coronary arteries

Explanation: **Explanation:** Atherosclerosis is a chronic inflammatory disease of the large and medium-sized muscular and elastic arteries [4]. The distribution of atherosclerotic lesions is not uniform; it preferentially involves areas of **turbulent blood flow**, such as branch points and ostia. **Why the Abdominal Aorta is Correct:** The **infrarenal abdominal aorta** is the most common and most severely affected site for atherosclerosis. This is due to the high degree of turbulence and decreased wall shear stress at the aortic bifurcation. In the descending order of frequency, the involvement is: 1. **Abdominal aorta** 2. Coronary arteries 3. Popliteal arteries 4. Internal carotid arteries 5. Circle of Willis **Analysis of Incorrect Options:** * **Thoracic Aorta (B):** While the aorta is a major site, the thoracic segment is significantly less affected than the abdominal segment [3]. Syphilitic aneurysms, however, preferentially involve the thoracic aorta. * **Coronary Arteries (D):** These are the second most common site [1]. While clinically more "famous" due to Myocardial Infarction, they are statistically less frequently involved than the abdominal aorta. * **Popliteal Artery (A):** This is the third most common site. It is a frequent cause of peripheral vascular disease (claudication) but follows the aorta and coronaries in prevalence [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Most common site for Aneurysm:** Abdominal Aorta (usually secondary to atherosclerosis) [2]. * **Most common site for Dissection:** Ascending Aorta (usually secondary to hypertension). * **Vasa Vasorum:** The abdominal aorta lacks vasa vasorum in its media compared to the thoracic aorta, making it more susceptible to ischemic weakening and plaque formation. * **Order of involvement (Mnemonic: "A C P I"):** **A**bdominal Aorta > **C**oronary > **P**opliteal > **I**nternal Carotid. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 507-508. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Cardiovascular Disease, pp. 271-272. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 511-512. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 491-492.

Question 13: What is the most common cause of thoracic aortic aneurysm?

A. Atherosclerosis (Correct Answer)
B. Tuberculosis
C. Cystic degeneration
D. Syphilis

Explanation: **Explanation:** **Atherosclerosis** is the most common cause of both abdominal and thoracic aortic aneurysms. In the thoracic aorta, it typically involves the descending portion. The underlying mechanism involves the formation of atherosclerotic plaques, which cause chronic inflammation and thickening of the intima. This impairs the diffusion of oxygen and nutrients to the underlying tunica media, leading to **ischemic atrophy** of the smooth muscle cells and loss of elastic tissue. Consequently, the vessel wall weakens and dilates under arterial pressure. **Analysis of Incorrect Options:** * **B. Tuberculosis:** While TB can cause "Rasmussen’s aneurysms" (involving pulmonary arteries) or infected (mycotic) aneurysms via direct extension from lymph nodes [1], it is a rare cause of generalized aortic aneurysms. * **C. Cystic Degeneration (Cystic Medial Necrosis):** This is the most common cause of aneurysms involving the **ascending aorta**, specifically in younger patients or those with connective tissue disorders like Marfan syndrome [1]. However, statistically, atherosclerosis remains more common for the thoracic aorta as a whole. * **D. Syphilis:** Historically a major cause of "tree-barking" aneurysms in the ascending aorta (due to endarteritis obliterans of the vasa vorum), its incidence has drastically declined with the advent of antibiotics. **High-Yield Clinical Pearls for NEET-PG:** * **Most common site for Aortic Aneurysm:** Abdominal Aorta (infra-renal) [1]. * **Most common cause of Abdominal Aortic Aneurysm (AAA):** Atherosclerosis [1]. * **Most common cause of Ascending Aortic Aneurysm:** Hypertension or Cystic Medial Necrosis (Marfan’s) [1]. * **Syphilitic Aneurysms:** Classically involve the **ascending aorta** and can lead to aortic regurgitation [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 510-512.

Question 14: All of the following are risk factors for atherosclerosis except?

A. Increased waist-hip ratio
B. Hyperhomocysteinemia
C. Decreased fibrinogen levels (Correct Answer)
D. Decreased HDL levels

Explanation: **Explanation:** Atherosclerosis is a chronic inflammatory response of the arterial wall to endothelial injury [1]. Risk factors are categorized into constitutional (non-modifiable) and acquired (modifiable). **Why "Decreased fibrinogen levels" is the correct answer:** Fibrinogen is an acute-phase reactant and a key component of the coagulation cascade. **Increased** (not decreased) levels of fibrinogen are associated with a pro-thrombotic state and increased blood viscosity, which promotes plaque formation and thrombosis. Therefore, decreased fibrinogen levels are actually protective or neutral, rather than a risk factor for atherosclerosis. **Analysis of Incorrect Options:** * **Increased waist-hip ratio:** This is a marker of central (visceral) obesity. It is a core component of Metabolic Syndrome and is strongly associated with insulin resistance, dyslipidemia, and systemic inflammation, all of which accelerate atherosclerosis [2]. * **Hyperhomocysteinemia:** High serum homocysteine levels cause endothelial dysfunction through the production of reactive oxygen species [1]. It is an independent risk factor for coronary artery disease and peripheral vascular disease. * **Decreased HDL levels:** HDL (High-Density Lipoprotein) is "good cholesterol" because it facilitates reverse cholesterol transport from the periphery to the liver [1]. Low levels of HDL (<40 mg/dL) remove this protective mechanism, increasing the risk of plaque accumulation [1]. **NEET-PG High-Yield Pearls:** * **Major Modifiable Risk Factors:** Hyperlipidemia (High LDL), Hypertension, Cigarette smoking, and Diabetes Mellitus [1]. * **Emerging Risk Factors:** C-Reactive Protein (CRP) – a strong predictor of MI; Lipoprotein(a) – an altered form of LDL; and Chlamydia pneumoniae infections [1, 2]. * **Morphology:** The "Fatty Streak" is the earliest lesion of atherosclerosis, seen even in children, while the "Atheromatous Plaque" is the characteristic advanced lesion. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 500-504. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Cardiovascular Disease, pp. 270-271.

Question 15: A 56-year-old woman diagnosed with cancer in her left breast underwent a mastectomy with axillary lymph node dissection. Postoperatively, she develops marked swelling of the left arm that has persisted for 6 months. On physical examination, her temperature is 36.9°C. Her left arm is not tender or erythematous, and it is not painful with movement or to touch, but it is enlarged with a doughy consistency. Which of the following is the most likely mechanism for these findings?

A. Cellulitis
B. Congestive heart failure
C. Decreased plasma oncotic pressure
D. Lymphedema (Correct Answer)

Explanation: **Explanation:** The patient presents with chronic, non-tender, unilateral arm swelling following a mastectomy and axillary lymph node dissection. This is a classic presentation of **secondary lymphedema** [1]. **1. Why Lymphedema is correct:** Lymphedema occurs due to the obstruction or disruption of lymphatic vessels. In breast cancer surgery, the removal of axillary lymph nodes (lymphadenectomy) and subsequent scarring (or radiation) impairs the drainage of interstitial fluid from the arm [1], [2]. This leads to the accumulation of protein-rich fluid in the subcutaneous tissue. Over time, this causes interstitial fibrosis, giving the limb a characteristic "doughy" or firm consistency (non-pitting edema in later stages) [1]. **2. Why the other options are incorrect:** * **Cellulitis:** This is an acute bacterial infection. It would present with systemic symptoms (fever), localized warmth, erythema (redness), and significant tenderness, which are absent here. * **Congestive Heart Failure (CHF):** CHF causes systemic venous congestion, leading to bilateral, dependent edema (usually in the legs), not isolated unilateral arm swelling [1]. * **Decreased Plasma Oncotic Pressure:** Seen in conditions like nephrotic syndrome or liver failure (hypoalbuminemia). This results in generalized, bilateral edema (anasarca), not localized swelling following surgery [1]. **3. NEET-PG High-Yield Pearls:** * **Most common cause of lymphedema worldwide:** Filariasis (infection by *Wuchereria bancrofti*) [1], [2]. * **Most common cause of lymphedema in developed countries:** Malignancy or its treatment (surgery/radiation) [1]. * **Stewart-Treves Syndrome:** A high-yield complication where long-standing chronic lymphedema (post-mastectomy) leads to the development of **Angiosarcoma**. * **Clinical Sign:** *Stemmer’s Sign* (inability to pinch the skin on the dorsal surface of the base of the second toe/finger) is diagnostic for lymphedema. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Hemodynamic Disorders, Thromboembolic Disease, and Shock, pp. 124-126. [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. 125-126.

Question 16: A woman has septic abortion with vegetation on the tricuspid valve. Where are septic emboli most likely to travel?

A. Septic infarcts to the lungs (Correct Answer)
B. The liver
C. Splenic infarcts
D. Emboli to the brain

Explanation: **Explanation:** The core concept here is the **anatomical pathway of venous circulation**. In a patient with a septic abortion, bacteria enter the pelvic venous plexus, traveling through the internal iliac veins to the inferior vena cava (IVC) and into the **right side of the heart**. 1. **Why Option A is correct:** The tricuspid valve is located between the right atrium and the right ventricle. Vegetations (infected thrombi) on this valve, when dislodged, follow the flow of blood from the right ventricle into the **pulmonary artery** [1], [2]. These septic emboli lodge in the pulmonary arterial tree, leading to **septic pulmonary infarcts** or abscesses [5]. 2. **Why Options B, C, and D are incorrect:** These options represent **systemic arterial embolization**. For an embolus to reach the liver (via hepatic artery), spleen, or brain, it must originate from the **left side of the heart** (mitral or aortic valves) [3] or pass through a right-to-left shunt (paradoxical embolism) [2]. Since the vegetation is on the tricuspid valve (right heart), it is filtered by the pulmonary capillary bed before it can reach the systemic circulation [2]. **High-Yield NEET-PG Pearls:** * **Right-sided Endocarditis:** Most commonly involves the tricuspid valve. It is classically associated with **IV drug users (IVDU)** (most common organism: *S. aureus*) and pelvic infections/septic abortions. * **Septic Abortion:** Usually involves *Staphylococcus aureus*, Gram-negative bacilli, or *Clostridium perfringens*. * **Complication:** The most common complication of right-sided infective endocarditis is **pulmonary embolism/abscess**, whereas left-sided endocarditis leads to systemic infarcts (brain, spleen, kidneys) [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. 144-145. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Hemodynamic Disorders, Thromboembolic Disease, and Shock, pp. 137-138. [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. 145-146. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Hemodynamic Disorders, Thromboembolic Disease, and Shock, pp. 136-137. [5] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 323-324.

Question 17: Sudden death, right-sided heart failure (cor pulmonale or cardiovascular collapse) occurs when?

A. Small pulmonary embolism
B. Massive pulmonary embolism
C. 60% or more of the pulmonary artery is obstructed with emboli (Correct Answer)
D. End artery obliteration

Explanation: ### Explanation **Correct Answer: C. 60% or more of the pulmonary artery is obstructed with emboli** **Underlying Medical Concept:** The physiological impact of a Pulmonary Embolism (PE) depends on the size of the embolus and the pre-existing cardiopulmonary status of the patient [1], [3]. Sudden death, acute right-sided heart failure (acute cor pulmonale), or cardiovascular collapse occurs when there is a massive mechanical obstruction of the pulmonary arterial tree [3]. Specifically, when **60% or more of the pulmonary circulation is obstructed**, the right ventricle cannot pump blood against the high resistance, leading to acute right ventricular failure, decreased left ventricular filling, and cardiogenic shock. **Analysis of Incorrect Options:** * **A. Small pulmonary embolism:** These are often clinically silent or cause minor symptoms like transient chest pain [1]. They do not cause immediate hemodynamic collapse because the remaining pulmonary vasculature can compensate for the obstruction. * **B. Massive pulmonary embolism:** While "massive PE" is clinically associated with hypotension and shock, it is a descriptive clinical term. Option C provides the specific **pathophysiological threshold** (60% obstruction) required to cause the fatal events mentioned in the question, making it the more precise academic answer for NEET-PG. * **D. End artery obliteration:** This typically leads to pulmonary infarction (usually peripheral and wedge-shaped) rather than sudden systemic cardiovascular collapse [4]. **High-Yield Clinical Pearls for NEET-PG:** * **Source:** >95% of pulmonary emboli arise from **Deep Vein Thrombosis (DVT)** of the lower limbs (above the knee) [2]. * **Saddle Embolus:** A large embolus that straddles the bifurcation of the main pulmonary artery; it is a classic cause of sudden death. * **Reflex Effects:** Death in PE is not just due to mechanical obstruction but also due to pulmonary secondary vasoconstriction triggered by the release of mediators like thromboxane A2. * **Morphology:** Look for **Lines of Zahn** (alternating pale layers of platelets/fibrin and dark layers of RBCs) to distinguish a pre-mortem thrombus from a post-mortem clot. **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. 144-145. [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. 143-144. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, p. 705. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Hemodynamic Disorders, Thromboembolic Disease, and Shock, pp. 137-138.

Question 18: An elderly female presents with fever, headache, and diplopia. Biopsy of the artery revealed panarteritis. What is the most probable diagnosis?

A. Nonspecific arteritis
B. Polyarteritis nodosa (PAN)
C. Wegener's granulomatosis
D. Temporal arteritis (Correct Answer)

Explanation: ### Explanation **Correct Option: D. Temporal arteritis (Giant Cell Arteritis)** **Why it is correct:** Temporal arteritis (GCA) is the most common systemic vasculitis in elderly patients (typically >50 years) [4]. The classic clinical triad includes **fever, headache, and visual disturbances** (like diplopia or amaurosis fugax) [2]. Histopathologically, it is characterized by **panarteritis**—inflammatory infiltrates involving all three layers of the arterial wall (intima, media, and adventitia) [4]. It frequently involves the branches of the carotid artery, particularly the temporal artery [3]. **Why other options are incorrect:** * **A. Nonspecific arteritis:** This is a general term and not a specific clinical diagnosis. It lacks the characteristic clinical-pathological correlation seen in GCA. * **B. Polyarteritis nodosa (PAN):** While PAN also shows panarteritis, it typically affects medium-sized vessels of the visceral organs (kidneys, heart, GI tract) and **spares the lungs** [5]. It is classically associated with Hepatitis B and presents with hypertension or abdominal pain, not typically isolated headache/diplopia in the elderly. * **C. Wegener's granulomatosis (GPA):** This involves the triad of upper respiratory tract, lower respiratory tract (lungs), and kidneys (GN). It is characterized by c-ANCA positivity and necrotizing granulomas, which are not the primary features described here. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard Diagnosis:** Temporal artery biopsy (look for fragmented internal elastic lamina and giant cells) [1]. * **Key Lab Finding:** Markedly elevated **ESR** (often >100 mm/hr) [2]. * **Associated Condition:** Strongly associated with **Polymyalgia Rheumatica** (proximal muscle pain and stiffness). * **Treatment:** Immediate high-dose corticosteroids to prevent permanent blindness [3]. * **Skip Lesions:** Biopsy must be long (2–3 cm) because the inflammation is segmental. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 516-517. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 686-687. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 688-689. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 515-516. [5] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 687-688.

Question 19: A 75-year-old man has experienced headaches for the past 2 months. On physical examination, his vital signs are temperature, 37°C; pulse, 68/min; respirations, 15/min; and blood pressure, 130/85 mm Hg. His right temporal artery is prominent, palpable, and painful to the touch. His heart rate is regular, and there are no murmurs. His erythrocyte sedimentation rate is 100 mm/hr. A temporal artery biopsy is performed, and the segment of the temporal artery excised is grossly thickened and shows focal microscopic granulomatous inflammation. He responds well to corticosteroid therapy. Which of the following complications of this disease is most likely to occur in untreated patients?

A. Blindness (Correct Answer)
B. Gangrene of the toes
C. Hemoptysis
D. Malignant hypertension

Explanation: ### Explanation **Diagnosis: Giant Cell (Temporal) Arteritis (GCA)** The clinical presentation—an elderly patient with new-onset headaches, a prominent/tender temporal artery, a significantly elevated ESR (100 mm/hr), and biopsy findings of granulomatous inflammation—is classic for **Giant Cell Arteritis** [1]. **1. Why "Blindness" is the correct answer:** The most feared complication of GCA is sudden, permanent visual loss [2]. This occurs due to **ophthalmic artery involvement**, leading to **Anterior Ischemic Optic Neuropathy (AION)** [1]. Because the inflammation is segmental (skip lesions), it can lead to rapid arterial occlusion. Prompt treatment with high-dose corticosteroids is mandatory to prevent this irreversible complication. **2. Why the other options are incorrect:** * **B. Gangrene of the toes:** This is characteristic of **Thromboangiitis obliterans (Buerger’s disease)**, which affects small-to-medium vessels in young smokers, or severe atherosclerosis. * **C. Hemoptysis:** This suggests pulmonary involvement, typical of **Granulomatosis with Polyangiitis (Wegener’s)** or Goodpasture syndrome. GCA typically spares the lungs. * **D. Malignant hypertension:** This is associated with **Polyarteritis Nodosa (PAN)** due to renal artery involvement and "flea-bitten" kidney, or systemic sclerosis. GCA does not typically cause renovascular hypertension. **3. High-Yield Clinical Pearls for NEET-PG:** * **Demographics:** Almost exclusively occurs in patients **>50 years** of age [1]. * **Association:** Strongly associated with **Polymyalgia Rheumatica (PMR)** (proximal muscle pain and stiffness). * **Pathology:** Granulomatous inflammation of the **tunica media** with fragmentation of the **internal elastic lamina**. * **Diagnosis:** Temporal artery biopsy is the gold standard, but because of **"skip lesions,"** a long segment of the artery must be sampled. * **Treatment:** Do not wait for biopsy results; start **Corticosteroids** immediately if GCA is suspected to prevent blindness. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 688-689. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Cardiovascular Disease, p. 266.

Question 20: What is the most common cause of thrombotic pulmonary embolism?

A. Progesterone pills
B. Deep vein thrombosis (Correct Answer)
C. Septicemia
D. Idiopathic

Explanation: **Explanation:** **1. Why Deep Vein Thrombosis (DVT) is correct:** Pulmonary Embolism (PE) is almost always a secondary complication of venous thromboembolism. In over **95% of cases**, the emboli originate from thrombi within the **deep veins of the lower extremities** [1], specifically those above the knee (popliteal, femoral, and iliac veins). These large-caliber veins allow for the formation of significant thrombi that can easily detach and travel through the inferior vena cava, right heart, and into the pulmonary arterial vasculature [3]. **2. Analysis of Incorrect Options:** * **Progesterone pills (A):** While oral contraceptives (especially those containing estrogen) increase the risk of hypercoagulability (Virchow’s Triad), they are a *risk factor* for DVT, not the direct cause of the embolism itself [2]. * **Septicemia (C):** Septicemia can lead to Disseminated Intravascular Coagulation (DIC) or septic emboli (often from endocarditis), but it is not the "most common" cause of standard thrombotic PE. * **Idiopathic (D):** While some cases occur without an identifiable provocative factor (unprovoked DVT/PE), the vast majority have a clear anatomical source in the deep venous system [3]. **3. High-Yield Clinical Pearls for NEET-PG:** * **Most common site:** Deep veins of the leg (above the knee). Thrombi in superficial veins (e.g., saphenous) rarely embolize [1]. * **Saddle Embolus:** A large embolus that straddles the bifurcation of the main pulmonary artery, often leading to sudden death. * **Consequences:** Most PEs (60-80%) are clinically silent. Pulmonary infarction is rare because the lung has a **dual blood supply** (Pulmonary and Bronchial arteries) [2]. * **Virchow’s Triad:** Stasis, Endothelial Injury, and Hypercoagulability are the three primary factors leading to DVT [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. 143-144. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 705-706. [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. 144-145.

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Atherosclerosis

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Hypertensive Vascular Disease

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Aneurysms and Dissection

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Vasculitis

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Venous Disease and Thrombosis

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Vascular Tumors

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Varicose Veins and Lymphatics

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Pathology of Vascular Interventions

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Vascular Diseases in Specific Organs

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Congenital Vascular Anomalies

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