Respiratory Pathology — MCQs

Respiratory Pathology Indian Medical PG Practice Questions and MCQs

Question 241: A patient presents with a severe form of atopic asthma. Which of the following changes would most likely be found in this patient's blood?

A. Basophilic leukocytosis
B. Eosinophilic leukocytosis (Correct Answer)
C. Lymphocytosis
D. Monocytosis

Explanation: **Explanation:** **Correct Answer: B. Eosinophilic leukocytosis** Atopic asthma is a classic example of a **Type I Hypersensitivity reaction**, mediated by IgE antibodies [1]. The pathophysiology involves the activation of **Th2-type T cells**, which secrete specific cytokines [2]: * **IL-4 & IL-13:** Stimulate B cells to synthesize IgE. * **IL-5:** Crucial for the recruitment, activation, and survival of **eosinophils**. In severe atopic asthma, eosinophils are recruited to the bronchial mucosa, where they release secondary mediators (like Major Basic Protein) that cause epithelial damage [2]. This systemic activation leads to **eosinophilic leukocytosis** in the peripheral blood and the presence of eosinophils in the sputum (often seen within Curschmann spirals or as Charcot-Leyden crystals). **Analysis of Incorrect Options:** * **A. Basophilic leukocytosis:** Rare; typically associated with myeloproliferative neoplasms like Chronic Myeloid Leukemia (CML). * **C. Lymphocytosis:** Characteristically seen in viral infections (e.g., Infectious Mononucleosis) or chronic lymphocytic leukemia (CLL). * **D. Monocytosis:** Associated with chronic infections (Tuberculosis), autoimmune diseases, or certain hematologic malignancies. **NEET-PG High-Yield Pearls:** 1. **Charcot-Leyden Crystals:** Composed of galectin-10 (eosinophil protein), these are pathognomonic findings in the sputum of asthmatics. 2. **Curschmann Spirals:** Whorled mucus plugs containing shed epithelium found in asthma. 3. **Airway Remodeling:** Chronic asthma leads to subepithelial fibrosis (thickening of the basement membrane) and hypertrophy of bronchial smooth muscle. 4. **Drug Link:** Monoclonal antibodies like **Mepolizumab** and **Reslizumab** target IL-5 to treat severe eosinophilic asthma. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, p. 210. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 688-689.

Question 242: What is the primary malignancy of the pleura?

A. Mesothelioma (Correct Answer)
B. Lymphoma
C. Lipoma
D. Squamous cell carcinoma

Explanation: **Explanation:** **Primary Concept:** The pleura is a serous membrane lined by **mesothelial cells**. Therefore, the primary malignancy arising directly from these cells is **Mesothelioma**. It is most commonly associated with chronic **asbestos exposure** (especially the amphibole type), typically occurring after a long latent period of 20–40 years [2]. **Analysis of Options:** * **A. Mesothelioma (Correct):** This is the definitive primary tumor of the pleura [2]. It can present as a localized or diffuse growth, often encasing the lung in a thick, gelatinous "rind." * **B. Lymphoma:** While lymphomas (like Primary Effusion Lymphoma) can involve the pleural space, they are considered hematological malignancies, not primary pleural tissue tumors. * **C. Lipoma:** This is a benign tumor of adipose tissue. While it can occur in the pleura or chest wall, it is not a malignancy [2]. * **D. Squamous cell carcinoma:** This is typically a primary malignancy of the **bronchial epithelium** (lung cancer). While it can metastasize to the pleura, it does not originate there [1]. **High-Yield NEET-PG Pearls:** * **Most Common Pleural Tumor:** Metastatic secondary tumors (from lung, breast, or GI tract) are actually more common than primary mesothelioma. * **Asbestos Association:** While asbestos is the major risk factor for mesothelioma, the most common cancer associated with asbestos exposure is actually **Bronchogenic Carcinoma** [1]. * **Markers:** Mesothelioma is typically **Calretinin positive** and **Cytokeratin 5/6 positive**, which helps differentiate it from adenocarcinoma (which is CEA positive) [1]. * **Morphology:** The most common histological subtype is the **Epithelioid type**, which carries a better prognosis than the sarcomatoid type [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, p. 731. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 339-340.

Question 243: A scar in lung tissue may transform into which type of malignancy?

A. Columnar cell carcinoma
B. Oat cell carcinoma
C. Squamous cell carcinoma
D. Adenocarcinoma (Correct Answer)

Explanation: **Explanation:** The correct answer is **Adenocarcinoma**. This phenomenon is historically referred to as **"Scar Carcinoma."** [1] **Why Adenocarcinoma is correct:** The association between chronic lung scarring (due to old tuberculosis, infarcts, chronic interstitial fibrosis, or metallic implants) and malignancy is most strongly linked to **Adenocarcinoma**. The underlying mechanism involves chronic inflammation and reactive hyperplasia of the bronchiolar or alveolar epithelium surrounding the scar tissue. Over time, these hyperplastic changes can progress to atypical adenomatous hyperplasia (AAH) and eventually to invasive adenocarcinoma, typically of the peripheral type [1]. **Why other options are incorrect:** * **Oat cell carcinoma (Small Cell Carcinoma):** This is a neuroendocrine tumor strongly associated with smoking and central (hilar) locations [1]. it arises from Kulchitsky cells, not from fibrotic scar tissue. * **Squamous cell carcinoma:** While it can occasionally be found peripherally, it is primarily associated with smoking-induced squamous metaplasia of the central bronchial epithelium [1]. * **Columnar cell carcinoma:** This is not a standard histological classification for lung primary malignancies; it is a descriptive term sometimes used for subtypes of adenocarcinoma (like the formerly named bronchioloalveolar carcinoma), but "Adenocarcinoma" is the definitive pathological diagnosis. **High-Yield NEET-PG Pearls:** * **Most common lung cancer in non-smokers and women:** Adenocarcinoma. * **Most common location:** Peripheral (unlike Squamous and Small cell, which are central) [1]. * **Driver Mutations:** Often associated with **EGFR** (especially in non-smoking Asian females), **ALK** rearrangements, or **KRAS** (smokers) [1]. * **Recent Perspective:** Modern pathology suggests that many "scar carcinomas" may actually be adenocarcinomas that *induced* a desmoplastic (fibrotic) response rather than arising from a pre-existing scar [1]. However, for exam purposes, the classic association remains. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 335-337.

Question 244: What is the characteristic pathological feature of pneumococcal pneumonia?

A. Consolidation of alveoli (Correct Answer)
B. Interstitial pneumonitis
C. Increased eosinophils
D. Hilar lymphadenopathy

Explanation: **Explanation:** **Pneumococcal pneumonia**, caused by *Streptococcus pneumoniae*, is the classic cause of **lobar pneumonia** [1]. The hallmark of this condition is **consolidation**, which refers to the replacement of air in the alveolar spaces by an inflammatory exudate (consisting of neutrophils, fibrin, and RBCs) [1],[2]. This process transforms the normally spongy lung tissue into a solid, liver-like mass [1]. **Why the correct answer is right:** * **Consolidation of alveoli:** In lobar pneumonia, the infection spreads rapidly through the **Pores of Kohn**, leading to uniform involvement of an entire lobe. The pathological stages (Congestion, Red Hepatization, Gray Hepatization, and Resolution) all center around the filling of alveolar spaces with exudate, which is the definition of consolidation [1],[2]. **Why the other options are incorrect:** * **B. Interstitial pneumonitis:** This is characteristic of **viral or atypical pneumonias** (e.g., Mycoplasma), where the inflammation is confined to the alveolar walls (interstitium) rather than the air spaces [3]. * **C. Increased eosinophils:** Eosinophilia is associated with allergic reactions, parasitic infections, or specific conditions like Löffler syndrome, not acute bacterial pneumonia. * **D. Hilar lymphadenopathy:** While it can occur, it is not the *characteristic* feature. It is more classically associated with **Primary Tuberculosis**, Sarcoidosis, or Malignancy [4]. **NEET-PG High-Yield Pearls:** * **Stages of Lobar Pneumonia:** 1. **Congestion** (Day 1-2): Vascular engorgement [1],[2]. 2. **Red Hepatization** (Day 3-4): Alveoli filled with RBCs, neutrophils, and fibrin; lung feels like liver [1],[2]. 3. **Gray Hepatization** (Day 5-7): RBCs disintegrate; fibrinopurulent exudate persists [1]. 4. **Resolution** (Day 8+): Enzymatic digestion of exudate [4]. * **Sputum:** Classically described as **"Rusty sputum"** due to altered blood. * **Most common cause:** *S. pneumoniae* remains the #1 cause of community-acquired pneumonia (CAP) [3]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 711-712. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 317-318. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, p. 715. [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. 193-194.

Question 245: Which type of lung tumour responds best to radiotherapy?

A. Small cell carcinoma (Correct Answer)
B. Squamous cell carcinoma
C. Adenocarcinoma
D. All lung tumours respond equally well to radiotherapy

Explanation: **Explanation:** **Small cell carcinoma (SCLC)** is the correct answer because it is characterized by a very high mitotic index and rapid cell turnover. In radiobiology, the **Law of Bergonié and Tribondeau** states that cells with high proliferative activity and low differentiation are the most radiosensitive. Since SCLC is a high-grade neuroendocrine tumor that divides rapidly, it shows a dramatic initial response to both radiotherapy and chemotherapy [1]. However, despite being "radiosensitive," it has a high tendency for early metastasis and recurrence, often leading to a poor long-term prognosis [1], [2]. **Why other options are incorrect:** * **Squamous cell carcinoma:** While more responsive than adenocarcinoma, it is considered only "moderately" radiosensitive. It is often treated surgically in early stages. * **Adenocarcinoma:** This is the most common type of lung cancer but is generally considered **radioresistant**. It responds poorly to radiation compared to SCLC and is primarily managed via surgical resection or targeted molecular therapies (e.g., EGFR inhibitors). * **Option D:** This is incorrect because lung tumors exhibit a spectrum of radiosensitivity based on their histopathological characteristics and growth fractions. **High-Yield Pearls for NEET-PG:** * **Most common lung cancer in non-smokers:** Adenocarcinoma [3]. * **Strongest association with smoking:** Small cell carcinoma and Squamous cell carcinoma (The "S" tumors are Central and Smoking-related) [3]. * **Paraneoplastic syndromes:** SCLC is most commonly associated with **SIADH** and **ACTH** production (Cushing syndrome), as well as Lambert-Eaton Myasthenic Syndrome [1]. * **Treatment of choice for SCLC:** Chemoradiotherapy (Surgery is rarely indicated due to early systemic spread) [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 725-727. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 337-338. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 336-337.

Question 246: What is true about lung carcinoma?

A. Squamous cell carcinoma is the most common carcinoma.
B. Squamous cell carcinoma causes myopathy.
C. Small cell carcinoma has the best prognosis.
D. None of the above. (Correct Answer)

Explanation: **Explanation:** The correct answer is **D (None of the above)** because all the provided statements regarding lung carcinoma are factually incorrect based on current epidemiological and clinical data. **Analysis of Options:** * **Option A is incorrect:** Globally and currently in India, **Adenocarcinoma** has surpassed squamous cell carcinoma to become the most common histological subtype of lung cancer in both smokers and non-smokers, as well as in women. [1] * **Option B is incorrect:** While squamous cell carcinoma (SCC) is associated with paraneoplastic syndromes, its classic association is **Hypercalcemia** (due to the secretion of Parathyroid Hormone-related Protein/PTHrP). Myopathy (specifically Lambert-Eaton Myasthenic Syndrome) is characteristically associated with **Small Cell Lung Carcinoma (SCLC)** [2]. * **Option C is incorrect:** Small cell carcinoma has the **worst prognosis** among all lung cancers [2]. It is highly aggressive, has a high growth fraction, and is usually metastatic at the time of diagnosis [1]. In contrast, Adenocarcinoma or Squamous cell carcinoma (Non-Small Cell Lung Cancer) generally have a better prognosis if detected early. **High-Yield NEET-PG Pearls:** 1. **Location:** Squamous cell and Small cell carcinomas are typically **Central/Hilar**, while Adenocarcinoma is typically **Peripheral** [1]. 2. **Small Cell Carcinoma (SCLC):** Strongly associated with smoking; originates from neuroendocrine (Kulchitsky) cells; positive for markers like Chromogranin, Synaptophysin, and CD56 [1]. 3. **Paraneoplastic Syndromes:** * **SCC:** Hypercalcemia (PTHrP). * **SCLC:** SIADH, ACTH (Cushing’s), and Lambert-Eaton Syndrome [2]. * **Adenocarcinoma:** Hypertrophic Pulmonary Osteoarthropathy (Clubbing). 4. **Driver Mutations:** Adenocarcinoma is frequently associated with mutations in **EGFR, ALK, and KRAS**, which are targets for modern biological therapies [2]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 335-338. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 725-727.

Question 247: Ghons complex refers to:

A. Healed parenchymal lesions
B. Necrotic lymph nodes
C. Parenchymal lesion along with inflamed lymph nodes (Correct Answer)
D. Complication in enlarged hilar lymph nodes

Explanation: **Explanation:** The **Ghon complex** is the hallmark of **primary tuberculosis**, typically occurring in individuals not previously exposed to *Mycobacterium tuberculosis* [1]. It represents the initial host response to the infection. **1. Why the Correct Answer is Right:** The Ghon complex consists of two distinct components that represent the spread of the bacilli from the initial site of infection: * **Ghon Focus:** A small (1–1.5 cm) area of granulomatous inflammation (subpleural, usually in the lower part of the upper lobe or upper part of the lower lobe). * **Nodal Component:** Involvement of the draining **hilar or tracheobronchial lymph nodes**, which undergo caseous necrosis. Therefore, the combination of the parenchymal lesion and the involved lymph nodes constitutes the complex. **2. Analysis of Incorrect Options:** * **Option A:** Healed parenchymal lesions are referred to as a **Ghon focus** (if isolated) or may progress to a **Ranke complex** if the Ghon complex undergoes progressive fibrosis and calcification [1]. * **Option B:** Necrotic lymph nodes are only one part of the complex. Without the primary parenchymal focus, it does not fulfill the definition of a Ghon complex. * **Option C:** This describes the anatomical spread from the lung parenchyma to the lymphatic system, which is the definition of the complex. * **Option D:** Complications of enlarged hilar nodes (like airway compression or fistula) are clinical consequences, not the definition of the complex itself. **High-Yield Clinical Pearls for NEET-PG:** * **Ranke Complex:** A Ghon complex that has undergone **calcification** (visible on X-ray) [1]. * **Simon’s Focus:** Secondary TB nodules found in the lung apices due to reactivation. * **Assmann Focus:** An area of infraclavicular cloudiness seen in secondary TB. * **Microscopy:** Look for **Caseating Granulomas** (central necrosis surrounded by epithelioid cells, Langhans giant cells, and lymphocytes) [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 382-384.

Question 248: Rasmussen's aneurysm is defined as:

A. A dilated vessel in a tubercular lung cavity (Correct Answer)
B. A dilation of the root of the aorta in valvular stenosis
C. A dilation of the aorta in syphilitic affection
D. A dilated renal vessel in hypertensive renal disease

Explanation: **Explanation:** **Rasmussen’s aneurysm** is a clinical phenomenon associated with chronic pulmonary tuberculosis. It refers to the inflammatory degradation and subsequent weakening of the wall of a **pulmonary artery branch** situated within or adjacent to a tuberculous cavity. As the cavity enlarges, the arterial wall loses its structural support and undergoes aneurysmal dilation. The rupture of this aneurysm is a classic cause of massive, life-threatening hemoptysis in patients with cavitary TB. **Analysis of Options:** * **Option A (Correct):** It accurately describes the pathology where chronic inflammation from a TB cavity leads to the weakening of a pulmonary vessel wall. * **Option B (Incorrect):** Dilation of the aortic root in valvular stenosis (specifically aortic stenosis) is known as **post-stenotic dilatation**, caused by turbulent blood flow. * **Option C (Incorrect):** Aortic dilation in syphilis is termed **Syphilitic (Luetic) Aortitis**, typically involving the ascending aorta and characterized by "tree-barking" of the intima due to endarteritis obliterans of the vasa vasorum. * **Option D (Incorrect):** Dilated renal vessels in hypertension are not specifically named Rasmussen’s; hypertensive renal disease is more commonly associated with hyaline or hyperplastic arteriolosclerosis. **High-Yield Clinical Pearls for NEET-PG:** * **Location:** Most commonly occurs in the branches of the pulmonary artery. * **Clinical Presentation:** Sudden, massive hemoptysis (often >300-600 ml in 24 hours). * **Radiology:** Contrast-enhanced CT (CECT) is the gold standard for diagnosis. * **Management:** Bronchial artery embolization (BAE) is often the first-line intervention, though Rasmussen’s specifically involves the pulmonary circulation.

Question 249: What is true regarding adenocarcinoma of the lung?

A. Causes 50% of lung cancers.
B. Is an unlikely histological variant in young patients.
C. Is associated with subcutaneous angiomyolipoma.
D. Typically has a peripheral location. (Correct Answer)

Explanation: **Explanation:** **Adenocarcinoma** is currently the most common histological subtype of lung cancer worldwide. 1. **Why Option D is Correct:** Adenocarcinoma typically arises from the distal airways and alveolar epithelium [1]. Therefore, it is characteristically located in the **periphery** of the lung [1]. This contrasts with Squamous Cell Carcinoma and Small Cell Carcinoma, which are typically central (hilar) in location [1]. 2. **Why Other Options are Incorrect:** * **Option A:** While it is the most common subtype, it accounts for approximately **38–40%** of lung cancers, not 50%. * **Option B:** Adenocarcinoma is actually the **most common** histological variant found in **young patients** (<45 years), non-smokers, and women. * **Option C:** There is no established association between lung adenocarcinoma and subcutaneous angiomyolipoma. Angiomyolipomas are classically associated with Tuberous Sclerosis, which is linked to *Lymphangioleiomyomatosis (LAM)* in the lung, not adenocarcinoma. **High-Yield Clinical Pearls for NEET-PG:** * **Driver Mutations:** Frequently associated with **EGFR** (common in non-smokers/Asian women), **KRAS** (common in smokers), and **ALK** rearrangements [1]. * **Precursor Lesion:** Atypical Adenomatous Hyperplasia (AAH) → Adenocarcinoma in situ (AIS, formerly Bronchioloalveolar carcinoma) → Invasive Adenocarcinoma [1]. * **Morphology:** Shows gland formation or mucin production (detected by PAS or Mucicarmine stains). * **IHC Markers:** Positive for **TTF-1** and **Napsin A**. * **Clinical Sign:** Often presents as a peripheral nodule/coin lesion on imaging and may be associated with hypertrophic osteoarthropathy (clubbing). **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 335-337.

Question 250: Which of the following is associated with carcinoma of the lung?

A. Chromium
B. Beryllium
C. Asbestos (Correct Answer)
D. Nickel

Explanation: **Explanation:** **Correct Option: C. Asbestos** Asbestos is the most well-documented occupational carcinogen associated with lung cancer [1]. While asbestos is famously linked to **malignant mesothelioma**, it is statistically more likely to cause **bronchogenic carcinoma** (the most common cancer in asbestos-exposed individuals) [2]. The risk is synergistically increased (up to 55-fold) in individuals who both smoke and have asbestos exposure [1]. **Analysis of Incorrect Options:** * **A. Chromium:** While hexavalent chromium is a known carcinogen associated with lung cancer (particularly in pigment and plating industries), it is less frequently tested as the primary association compared to asbestos in standard medical curricula. * **B. Beryllium:** Exposure (berylliosis) primarily leads to chronic granulomatous disease (similar to sarcoidosis). While classified as a Group 1 carcinogen, its association is less common than asbestos. * **D. Nickel:** Nickel refining is associated with cancers of the nasal cavity and lungs, but like chromium, it is a secondary association in the hierarchy of high-yield exam topics. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cancer in Asbestosis:** Bronchogenic Carcinoma (NOT Mesothelioma) [2]. * **Most specific cancer for Asbestosis:** Malignant Mesothelioma [1]. * **Synergistic Risk:** Smoking + Asbestos = Massive increase in Bronchogenic Carcinoma risk; however, smoking does **not** increase the risk of Mesothelioma [1]. * **Pathognomonic finding:** **Ferruginous bodies** (asbestos bodies)—golden-brown, fusiform/beaded rods coated with iron-containing protein (Prussian blue positive). * **Radiology:** Pleural plaques (most common finding) usually involve the parietal pleura and the diaphragm [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. 221-222. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, p. 699.

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Congenital Anomalies

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Atelectasis and Acute Lung Injury

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Restrictive Pulmonary Diseases

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Pulmonary Vascular Diseases

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Lung Tumors

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Pleural Diseases

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Interstitial Lung Diseases

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Occupational Lung Diseases

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