Respiratory Pathology — MCQs

Respiratory Pathology Indian Medical PG Practice Questions and MCQs

Question 341: Which type of lung carcinoma is most commonly associated with causing Superior Vena Cava (SVC) syndrome?

A. Squamous cell carcinoma
B. Adenocarcinoma
C. Small cell carcinoma (Correct Answer)
D. Anaplastic carcinoma

Explanation: **Small Cell Carcinoma (SCLC)** is the most common cause of Superior Vena Cava (SVC) syndrome among lung malignancies [2]. This is primarily due to its **central location** and aggressive growth pattern [1]. SCLC typically arises from the peribronchial neuroendocrine cells and rapidly involves the hilar and mediastinal lymph nodes [1]. Because the SVC is a thin-walled, low-pressure vessel located in the tight confines of the middle mediastinum, it is easily compressed by the bulky mediastinal lymphadenopathy characteristic of SCLC [2]. **Analysis of Incorrect Options:** * **Squamous Cell Carcinoma:** While also centrally located, it is more likely to cause bronchial obstruction (leading to collapse or post-obstructive pneumonia) or cavitate [3]. It is the second most common cause of SVC syndrome but lags behind SCLC in frequency. * **Adenocarcinoma:** This is the most common type of lung cancer overall, but it is typically **peripherally located** [3]. Therefore, it is less likely to compress central mediastinal structures like the SVC. * **Anaplastic Carcinoma:** This is a rare, undifferentiated subtype. While aggressive, it does not have the specific predilection for the central mediastinal involvement seen in SCLC. **High-Yield Clinical Pearls for NEET-PG:** * **SVC Syndrome Presentation:** Look for "Pemberton’s sign," facial puffiness, plethoric neck veins, and "feeling of fullness" in the head when bending forward [2]. * **Most Common Cause Overall:** Malignancy (approx. 70-90%), with Lung Cancer being #1 and Lymphoma being #2. * **SCLC Associations:** Strongly linked to smoking, **Paraneoplastic syndromes** (SIADH, ACTH production, Lambert-Eaton Syndrome), and "Oat cell" morphology on histology [1]. * **Management:** SVC syndrome in SCLC is often a medical emergency but is highly responsive to chemotherapy and radiation. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 337-338. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, p. 725. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 336-337.

Question 342: Which of the following classifications is used for pulmonary adenocarcinoma?

A. Parkland classification
B. Waterston's classification
C. Chicago classification
D. Noguchi's classification (Correct Answer)

Explanation: **Explanation:** **Noguchi’s Classification** is a histopathological classification used specifically for **small peripheral pulmonary adenocarcinomas** (specifically those $\leq$ 2 cm in diameter). It categorizes these tumors into six types (A to F) based on their growth patterns and degree of alveolar wall thickening. * **Types A, B, and C** represent "localized bronchioloalveolar carcinoma" (now largely termed Adenocarcinoma In Situ) and carry a very high 5-year survival rate (nearly 100%) [1]. * **Types D, E, and F** represent invasive adenocarcinoma and carry a significantly poorer prognosis. **Analysis of Incorrect Options:** * **A. Parkland Classification:** Used in surgery to grade the severity of **acute cholecystitis** based on gallbladder inflammation and adhesions. * **B. Waterston’s Classification:** A historical risk-stratification system for **Esophageal Atresia**, based on birth weight and the presence of pneumonia or associated anomalies. * **C. Chicago Classification:** The gold standard for interpreting **high-resolution esophageal manometry** to diagnose motility disorders like Achalasia Cardia. **High-Yield Clinical Pearls for NEET-PG:** * **Most common lung cancer:** Adenocarcinoma is now the most common histological subtype in both smokers and non-smokers [1]. * **Driver Mutations:** Adenocarcinoma is frequently associated with **EGFR** mutations (common in Asian non-smoking females), **ALK** rearrangements, and **KRAS** mutations [1]. * **Staining:** Adenocarcinomas are typically positive for **TTF-1** (Thyroid Transcription Factor-1) and **Napsin A**. * **Lepidic Growth:** This term refers to tumor cells "crawling" along the pre-existing alveolar walls without stromal invasion, a hallmark of early-stage adenocarcinoma [1]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 335-337.

Question 343: Ghons focus is seen in?

A. Amoebiasis
B. Lepromatous Leprosy
C. Primary Tuberculosis (Correct Answer)
D. Syphilis

Explanation: **Explanation:** **Ghon’s focus** is the pathognomonic lesion of **Primary Tuberculosis**. It represents the initial site of infection in a person who has not been previously exposed to *Mycobacterium tuberculosis* [1]. 1. **Why Primary Tuberculosis is correct:** When tubercle bacilli are inhaled, they settle in the subpleural region (usually the lower part of the upper lobe or upper part of the lower lobe). This results in a 1–1.5 cm area of grey-white inflammatory consolidation with central **caseous necrosis**, known as the **Ghon focus** [2]. * **Ghon Complex:** Ghon focus + Lymphangitis + Draining hilar lymph node involvement [2]. * **Ranke Complex:** A Ghon complex that has undergone progressive fibrosis and calcification (visible on X-ray). 2. **Why other options are incorrect:** * **Amoebiasis:** Caused by *Entamoeba histolytica*, it typically presents with "anchovy sauce" liver abscesses or flask-shaped ulcers in the colon. * **Lepromatous Leprosy:** A systemic manifestation of *M. leprae* characterized by "leonine facies," globi (macrophages filled with acid-fast bacilli), and symmetric nerve involvement, but not Ghon foci. * **Syphilis:** Characterized by chancres (primary), condyloma lata (secondary), or **Gummas** (tertiary). Syphilitic lesions are granulomatous but distinct from the caseating Ghon focus. **High-Yield Clinical Pearls for NEET-PG:** * **Location:** Ghon focus is usually **subpleural** and mid-zonal. * **Secondary TB:** Characterized by **Assmann focus** (infraclavicular/apex) and cavitary lesions [3]. * **Microscopy:** Look for **Langhans giant cells** (horseshoe arrangement of nuclei) and Ziehl-Neelsen (ZN) stain positivity. * **Simmonds Focus:** An apical nodule seen in the early stages of secondary TB. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 379-380. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 383-384. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 320-321.

Question 344: Panacinar emphysema is typically seen in which condition?

A. Smoking
B. Chronic bronchitis
C. Alpha-1 antitrypsin deficiency (Correct Answer)
D. Spontaneous pneumothorax

Explanation: **Explanation:** **Panacinar (Panlobular) emphysema** is characterized by the uniform enlargement of air spaces from the level of the respiratory bronchiole to the terminal blind alveoli [1]. It involves the entire acinus and is most commonly seen in the **lower zones** of the lungs. 1. **Why Alpha-1 Antitrypsin (AAT) Deficiency is correct:** AAT is a protease inhibitor that normally neutralizes **neutrophil elastase** [1]. In its absence, elastase unchecked destroys the elastic tissue of the alveolar walls throughout the acinus, leading to panacinar emphysema [2]. This is a classic genetic association frequently tested in NEET-PG. 2. **Why other options are incorrect:** * **Smoking:** Primarily associated with **Centriacinar (Centrilobular) emphysema**, where the damage is confined to the proximal part of the acinus (respiratory bronchioles), typically affecting the **upper lobes** [1]. * **Chronic Bronchitis:** While often co-existing with emphysema (as COPD), it is defined by airway inflammation and mucus hypersecretion rather than the specific alveolar destruction pattern of panacinar emphysema [1]. * **Spontaneous Pneumothorax:** This is a clinical complication often resulting from the rupture of subpleural blebs or bullae, most commonly associated with **Distal Acinar (Paraseptal) emphysema** [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Centriacinar:** Most common type; associated with Smoking; Upper lobes [1]. * **Panacinar:** Associated with $\alpha$1-Antitrypsin deficiency; Lower lobes [2]. * **Paraseptal:** Associated with spontaneous pneumothorax in young adults; involves distal acinus near the pleura [1]. * **Microscopy:** Look for "floating alveolar septa" due to the loss of attachment points. * **Genetics:** AAT deficiency is linked to the **PiZZ phenotype** (most severe) and may also present with **liver cirrhosis** (PAS-positive, diastase-resistant globules) [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 683-685. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Liver and Gallbladder, pp. 856-858.

Question 345: Which of the following is a feature of small cell carcinoma?

A. It is the commonest malignancy of the lung.
B. It is associated with paraneoplastic syndromes. (Correct Answer)
C. It does not cause Superior Vena Cava (SVC) syndrome.
D. None of the above.

Explanation: ### **Explanation** **Small Cell Carcinoma (SCLC)** is a highly aggressive, neuroendocrine tumor of the lung, typically arising in the central airways [1]. It is strongly associated with heavy smoking. **1. Why Option B is Correct:** SCLC is derived from **neuroendocrine (Kulchitsky) cells** [1]. These cells contain neurosecretory granules that can produce various hormones, leading to **Paraneoplastic Syndromes** [2]. It is the lung cancer most frequently associated with these syndromes, most notably: * **SIADH** (Syndrome of Inappropriate Antidiuretic Hormone): Leading to hyponatremia. * **Ectopic ACTH production:** Leading to Cushing syndrome. * **Lambert-Eaton Myasthenic Syndrome:** Autoantibodies against voltage-gated calcium channels. **2. Why Other Options are Incorrect:** * **Option A:** The commonest malignancy of the lung is **Adenocarcinoma**, not SCLC [3]. Adenocarcinoma is also the most common type in non-smokers and women. * **Option C:** SCLC is a **centrally located tumor** that tends to invade the mediastinum early [1]. Because of its central location and rapid growth, it is a **common cause of Superior Vena Cava (SVC) syndrome** due to extrinsic compression of the SVC [4]. **3. NEET-PG High-Yield Pearls:** * **Microscopy:** Shows "Oat cells" with scant cytoplasm, hyperchromatic nuclei, and **Azzopardi effect** (DNA staining of vessel walls due to necrotic tumor cells) [1]. * **Genetics:** Nearly 100% show mutations in **TP53** and **RB1**. * **Markers:** Positive for Chromogranin A, Synaptophysin, and CD56 [1]. * **Treatment:** Unlike Non-Small Cell Lung Cancer (NSCLC), SCLC is usually disseminated at the time of diagnosis; therefore, it is treated primarily with **chemotherapy/radiotherapy** rather than surgery [2]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 337-338. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 725-727. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 336-337. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 724-725.

Question 346: Which of the following is NOT a typical histological feature of Hypersensitivity Pneumonitis?

A. Interstitial pneumonitis
B. Non-caseating granuloma
C. Eosinophilic abscess (Correct Answer)
D. Interstitial fibrosis

Explanation: **Explanation:** Hypersensitivity Pneumonitis (HP), also known as Extrinsic Allergic Alveolitis, is an immunologically mediated inflammatory lung disease caused by an exaggerated immune response (Type III and Type IV hypersensitivity) to inhaled organic antigens [1] [2]. **Why "Eosinophilic Abscess" is the correct answer:** Eosinophilic abscesses and significant tissue eosinophilia are **not** features of Hypersensitivity Pneumonitis. These findings are characteristic of **Tropical Pulmonary Eosinophilia** or **Churg-Strauss Syndrome (EGPA)**. Despite being an "allergic" response, the inflammatory infiltrate in HP is predominantly lymphocytic, not eosinophilic. **Analysis of Incorrect Options:** * **Interstitial Pneumonitis:** This is the hallmark of HP. It typically presents as a patchy mononuclear cell infiltrate (predominantly T-lymphocytes) in the alveolar walls, often with a bronchiolocentric distribution [1]. * **Non-caseating Granuloma:** Found in approximately 60-70% of cases, these are small, loose, ill-defined non-caseating granulomas [1]. They are a classic diagnostic clue for HP, distinguishing it from other interstitial lung diseases. * **Interstitial Fibrosis:** This occurs in the **chronic phase** of the disease. Prolonged exposure to the antigen leads to fibroblast proliferation and collagen deposition, which can eventually result in a "honeycomb lung" appearance. **NEET-PG High-Yield Pearls:** * **Classic Triad of HP:** 1. Interstitial pneumonitis (lymphocytic), 2. Non-caseating granulomas (loose), 3. Peribronchiolar fibrosis. * **Common Triggers:** Farmer’s Lung (Actinomycetes in moldy hay), Bird Fancier’s Lung (avian proteins), Air Conditioner Lung (thermophilic bacteria) [2]. * **Key Distinction:** Unlike Sarcoidosis, the granulomas in HP are **poorly formed** and located near bronchioles rather than along lymphatics. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 701-702. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 332-333.

Question 347: Which of the following statements about lung carcinoma is true?

A. Squamous cell variant accounts for 70% of all lung cancer.
B. Oat cell variant typically presents with cavitation.
C. Oat cell variant is typically associated with hilar adenopathy. (Correct Answer)
D. Adenocarcinoma variant is typically central in location.

Explanation: **Explanation:** **Correct Answer: C. Oat cell variant is typically associated with hilar adenopathy.** Oat cell carcinoma (Small Cell Lung Carcinoma - SCLC) is a highly aggressive neuroendocrine tumor. It typically arises from the **central/perihilar** airways [1] and is characterized by early and widespread lymphatic spread. Consequently, it almost always presents with massive **hilar and mediastinal lymphadenopathy** [1], often appearing as a "bulging" perihilar mass on chest X-rays. **Analysis of Incorrect Options:** * **Option A:** Squamous cell carcinoma accounts for approximately 25-30% of cases. **Adenocarcinoma** is currently the most common histological variant, accounting for nearly 40-50% of all lung cancers. * **Option B:** Cavitation is a classic feature of **Squamous Cell Carcinoma** (due to central necrosis) [2], [3]. Small cell (Oat cell) carcinoma rarely, if ever, undergoes cavitation [1]. * **Option D:** Adenocarcinoma is typically **peripheral** in location, often arising in areas of prior scarring (scar carcinoma). Squamous cell and Small cell carcinomas are the variants that are typically central [1], [3]. **High-Yield NEET-PG Pearls:** * **SCLC (Oat Cell):** Strongly associated with smoking; shows "Azzopardi effect" (DNA staining of vessel walls); associated with paraneoplastic syndromes like **SIADH** and **ACTH** production. * **Squamous Cell Carcinoma:** Associated with **Hypercalcemia** (due to PTHrP). * **Adenocarcinoma:** Most common variant in **non-smokers** and women; often associated with **EGFR** mutations and **ALK** rearrangements. * **Pancoast Tumor:** Usually Squamous or Adenocarcinoma at the apex [4], causing Horner’s syndrome [4]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 337-338. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 723-724. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 336-337. [4] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 334-335.

Question 348: What condition is indicated by the presence of Creola bodies in sputum?

A. Bronchial Asthma (Correct Answer)
B. Chronic Bronchitis
C. Bronchogenic Carcinoma
D. Pulmonary Tuberculosis

Explanation: **Bronchial Asthma** is the correct answer. **Creola bodies** are compact, multi-layered clusters of desquamated ciliated columnar epithelial cells found in the sputum of asthmatic patients. They result from the intense airway inflammation and mechanical sloughing of the bronchial mucosa characteristic of an asthma exacerbation [1]. **Analysis of Options:** * **Bronchial Asthma (Correct):** In addition to Creola bodies, asthma is associated with other classic sputum findings: **Curschmann spirals** (coiled mucus plugs from small airways) and **Charcot-Leyden crystals** (eosinophil-derived galectin-10) [1]. * **Chronic Bronchitis:** While this involves mucus hypersecretion and goblet cell hyperplasia, the characteristic finding is an increased **Reid Index** (>0.4) on histopathology, not Creola bodies. * **Bronchogenic Carcinoma:** Sputum cytology here would typically show malignant cells with nuclear pleomorphism, hyperchromasia, and keratin pearls (in squamous cell carcinoma), rather than organized clusters of benign ciliated cells. * **Pulmonary Tuberculosis:** This is characterized by **caseating granulomas** and the presence of Acid-Fast Bacilli (AFB) on Ziehl-Neelsen staining. **NEET-PG High-Yield Pearls:** * **Creola Bodies:** Ciliated epithelial cell clusters (Asthma). * **Curschmann Spirals:** Whorled mucus plugs (Asthma) [1]. * **Charcot-Leyden Crystals:** Rhomboid-shaped crystals from eosinophil breakdown (Asthma/Eosinophilic conditions). * **Reid Index:** Ratio of bronchial gland thickness to total wall thickness (Increased in Chronic Bronchitis). * **Ferruginous Bodies:** Asbestos fibers coated with iron (Asbestosis). **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 688-690.

Question 349: Which paraneoplastic syndrome is not associated with small cell carcinoma of the lung?

A. Immune thrombocytopenic purpura (Correct Answer)
B. Ectopic ACTH production
C. Syndrome of inappropriate antidiuretic hormone (SIADH)
D. Carcinoid syndrome

Explanation: Small cell carcinoma (SCLC) is a neuroendocrine tumor derived from **Kulchitsky cells**. It is notorious for its high metabolic activity and its ability to secrete various hormones and antibodies, making it the lung cancer most frequently associated with paraneoplastic syndromes [1]. **Why Option A is Correct:** **Immune thrombocytopenic purpura (ITP)** is not a classic paraneoplastic manifestation of SCLC. While SCLC can cause hematologic abnormalities like anemia of chronic disease or Trousseau syndrome (migratory thrombophlebitis), ITP is more commonly associated with lymphoproliferative disorders (e.g., CLL) or systemic autoimmune diseases (e.g., SLE). **Why the Other Options are Incorrect:** * **Ectopic ACTH Production (Option B):** SCLC is the most common cause of ectopic Cushing syndrome. Patients present with rapid-onset hypertension, hypokalemia, and hyperglycemia rather than the classic "buffalo hump" or "moon facies." * **SIADH (Option C):** SCLC is the leading cause of SIADH, where excessive ADH leads to water retention and profound **euvolemic hyponatremia**. [1] * **Carcinoid Syndrome (Option D):** Since SCLC is a neuroendocrine tumor, it can rarely secrete serotonin, leading to flushing, diarrhea, and wheezing, though this is more typical of bronchial carcinoids. [3] **High-Yield Clinical Pearls for NEET-PG:** * **Lambert-Eaton Myasthenic Syndrome (LEMS):** A crucial SCLC paraneoplastic syndrome caused by antibodies against presynaptic voltage-gated calcium channels. * **Rule of Thumb:** SCLC = **S**IADH, **S**eizures (due to hyponatremia), and **S**ubacute cerebellar degeneration. * **Squamous Cell Carcinoma:** Classically associated with **Hypercalcemia** (due to PTHrP production) [2]. Remember: **S**quamous = **S**tones (Calcium). **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 725-727. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 338-339. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 337-338.

Question 350: A Ghon complex of the lung typically undergoes which of the following changes?

A. Cavitation
B. Calcification (Correct Answer)
C. Progression to tuberculous pneumonia
D. Progression to miliary tuberculosis

Explanation: ### Explanation **Correct Answer: B. Calcification** **Understanding the Concept:** A **Ghon complex** is the hallmark of **primary tuberculosis**. It consists of three components: a parenchymal subpleural lesion (Ghon focus), lymphangitis, and involved hilar lymph nodes. In approximately 90-95% of immunocompetent individuals, the cell-mediated immune response successfully contains the infection. This leads to healing through **fibrosis and dystrophic calcification** [1]. When a Ghon complex undergoes significant calcification and is visible on a chest X-ray, it is referred to as a **Ranke complex**. **Analysis of Incorrect Options:** * **A. Cavitation:** This is a characteristic feature of **Secondary (Reactivation) Tuberculosis**, not primary TB. Cavitation occurs due to a hypersensitivity response leading to extensive caseous necrosis, typically in the lung apices [1]. * **C & D. Progression to Tuberculous Pneumonia/Miliary TB:** While these are possible complications of progressive primary TB (especially in children or immunocompromised patients), they are **not the typical fate** [1]. The "typical" or most common outcome of a Ghon complex is healing and calcification. **NEET-PG High-Yield Pearls:** * **Ghon Focus Location:** Usually located in the lower part of the upper lobe or upper part of the lower lobe, close to the pleura. * **Ranke Complex:** Ghon complex + Calcification (visible on Radiology). * **Simon Focus:** A calcified nodule at the lung apex resulting from hematogenous seeding during primary infection; it is a common site for future reactivation. * **Type of Necrosis:** Tuberculosis is the classic example of **Caseous necrosis** (cheese-like appearance) [2]. * **Microscopy:** Look for **Langhans giant cells** (peripheral arrangement of nuclei) and epithelioid granulomas [2]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 320-321. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 383-384.

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