A 15-year-old boy is brought to the emergency department with a 30 minute history of difficulty breathing. He was playing basketball in gym class when he suddenly felt pain in the right side of his chest that got worse when he tried to take a deep breath. Physical exam reveals a tall, thin boy taking rapid shallow breaths. There are decreased breath sounds in the right lung fields and the right chest is hyperresonant to percussion. Which of the following is true of the lesions that would most likely be seen in this patient's lungs?
Q12
A 56-year-old man comes to the physician for a follow-up examination one week after a chest x-ray showed a solitary pulmonary nodule. He has no history of major medical illness. He has smoked 1 pack of cigarettes daily for the past 30 years. Physical examination shows no abnormalities. A tuberculin skin test is negative. A CT scan of the chest shows a 2.1-cm well-circumscribed, calcified nodule in the periphery of the right lower lung field. A CT-guided biopsy of the lesion is performed. Histological examination of the biopsy specimen shows regions of disorganized hyaline cartilage interspersed with myxoid regions and clefts of ciliated epithelium. Which of the following is the most likely diagnosis?
Q13
A 72-year-old retired shipyard worker received a chest x-ray as part of a routine medical work-up. The radiologist reported incidental findings suggestive of an occupational lung disease. Which of the following descriptions is most consistent with this patient's film?
Q14
A 66-year-old man presents with severe respiratory distress. He was diagnosed with pulmonary hypertension secondary to occupational pneumoconiosis. Biopsy findings of the lung showed ferruginous bodies. What is the most likely etiology?
Q15
A 58-year-old man is brought to the emergency department after a witnessed tonic-clonic seizure. His wife says he has had a persistent dry cough for 6 months. During this time period, he has also had fatigue and a 4.5-kg (10-lb) weight loss. The patient has no history of serious illness and does not take any medications. He has smoked 1 pack of cigarettes daily for 35 years. He is confused and oriented only to person. Laboratory studies show a serum sodium concentration of 119 mEq/L and glucose concentration of 102 mg/dL. An x-ray of the chest shows an irregular, poorly demarcated density at the right hilum. Microscopic examination of this density is most likely to confirm which of the following diagnoses?
Q16
A 68-year-old man presents to the office with progressive shortness of breath and cough. A chest X-ray shows prominent hilar lymph nodes and scattered nodular infiltrates. Biopsy of the latter reveals noncaseating granulomas. This patient most likely has a history of exposure to which of the following?
Q17
A 61-year-old male presents to your office with fever and dyspnea on exertion. He has been suffering from chronic, non-productive cough for 1 year. You note late inspiratory crackles on auscultation. Pulmonary function tests reveal an FEV1/FVC ratio of 90% and an FVC that is 50% of the predicted value. Which of the following would you most likely see on a biopsy of this patient's lung?
Q18
A 58-year-old woman presents to the physician with a cough that began 6 years ago, as well as intermittent difficulty in breathing for the last year. There is no significant sputum production. There is no history of rhinorrhea, sneezing or nose congestion. She has been a chronic smoker from early adulthood. Her temperature is 36.9°C (98.4°F), the heart rate is 80/min, the blood pressure is 128/84 mm Hg, and the respiratory rate is 22/min. A physical examination reveals diffuse end-expiratory wheezing with prolonged expiration on chest auscultation; breath sounds and heart sounds are diminished. There is no cyanosis, clubbing or lymphadenopathy. Her chest radiogram shows hyperinflated lungs bilaterally and a computed tomography scan of her chest is shown in the picture. Which of the following best describes the pathogenesis of the condition of this patient?
Q19
A 32-year-old man comes to the physician for a 1-month history of fever, chest pain with deep breathing, and a 4-kg (9 lb) weight loss. His temperature is 38°C (100.4°F). An x-ray of the chest shows a subpleural nodule in the right lower lobe with right hilar lymphadenopathy. Histological examination of a right hilar lymph node biopsy specimen shows several granulomas with acellular cores. Which of the following is the most likely diagnosis?
Q20
An investigator is studying the effects of influenza virus on human lung tissue. Biopsy specimens of lung parenchyma are obtained from patients recovering from influenza pneumonia and healthy control subjects. Compared to the lung tissue from the healthy control subjects, the lung tissue from the affected patients is most likely to show which of the following findings on histopathologic examination?
Pulmonary US Medical PG Practice Questions and MCQs
Question 11: A 15-year-old boy is brought to the emergency department with a 30 minute history of difficulty breathing. He was playing basketball in gym class when he suddenly felt pain in the right side of his chest that got worse when he tried to take a deep breath. Physical exam reveals a tall, thin boy taking rapid shallow breaths. There are decreased breath sounds in the right lung fields and the right chest is hyperresonant to percussion. Which of the following is true of the lesions that would most likely be seen in this patient's lungs?
A. Found in the lower lobes
B. Related to liver failure
C. Found predominantly in the lower lobes
D. Related to smoking
E. Found near the pleura (Correct Answer)
Explanation: ***Found near the pleura***
- This patient's symptoms (sudden chest pain, difficulty breathing, decreased breath sounds, hyperresonance) are classic for a **spontaneous pneumothorax**.
- In primary spontaneous pneumothorax, the air leak typically results from the rupture of **subpleural blebs** or **bullae**, which are small air-filled sacs located just beneath the visceral pleura at the lung apices.
- This is the key anatomic characteristic of the lesions responsible for this condition.
*Found predominantly in the lower lobes*
- Blebs causing primary spontaneous pneumothorax are typically found in the **apical (upper) regions** of the lung, not the lower lobes.
- The apices experience greater mechanical stress during breathing, making blebs more likely to form and rupture there.
- Lower lobe involvement is not characteristic of primary spontaneous pneumothorax in young, healthy individuals.
*Related to liver failure*
- **Liver failure** is not directly associated with the formation of subpleural blebs or bullae that cause spontaneous pneumothorax.
- Liver failure can cause respiratory issues like **hepatopulmonary syndrome** or **ascites-related diaphragmatic splinting**, but not this specific type of lung lesion.
*Related to smoking*
- Smoking is a significant risk factor for **secondary spontaneous pneumothorax** by causing emphysema and damaging lung parenchyma, leading to bullae formation.
- However, in a **15-year-old boy** with a primary spontaneous pneumothorax, the underlying blebs are often congenital or idiopathic, and smoking is less likely to be the direct cause.
- The key feature is the **subpleural location** of these blebs, typically at the lung apices.
Question 12: A 56-year-old man comes to the physician for a follow-up examination one week after a chest x-ray showed a solitary pulmonary nodule. He has no history of major medical illness. He has smoked 1 pack of cigarettes daily for the past 30 years. Physical examination shows no abnormalities. A tuberculin skin test is negative. A CT scan of the chest shows a 2.1-cm well-circumscribed, calcified nodule in the periphery of the right lower lung field. A CT-guided biopsy of the lesion is performed. Histological examination of the biopsy specimen shows regions of disorganized hyaline cartilage interspersed with myxoid regions and clefts of ciliated epithelium. Which of the following is the most likely diagnosis?
A. Small cell lung carcinoma
B. Bronchogenic cyst
C. Eosinophilic granuloma
D. Pulmonary hamartoma (Correct Answer)
E. Mature teratoma
Explanation: ***Pulmonary hamartoma***
- The histological description of **disorganized hyaline cartilage**, **myxoid regions**, and **ciliated epithelium** is pathognomonic for a pulmonary hamartoma, which is a benign tumor-like malformation.
- The features of a **well-circumscribed** and **calcified nodule** on CT are also highly suggestive of a hamartoma.
*Small cell lung carcinoma*
- This is a **highly malignant neuroendocrine tumor** that typically presents as a centrally located mass, often with associated paraneoplastic syndromes.
- Histologically, it would show small, dark, round to oval cells with scant cytoplasm, not mature cartilage or epithelium.
*Bronchogenic cyst*
- These are **congenital pulmonary anomalies** that are typically fluid-filled and lined by ciliated epithelium, but they do not contain cartilage or myxoid stromal elements.
- They are usually cystic on imaging and rarely calcified in the described manner.
*Eosinophilic granuloma*
- This is a form of **Langerhans cell histiocytosis**, characterized by the proliferation of Langerhans cells and an inflammatory infiltrate rich in eosinophils.
- It would present with **star-shaped nodules** or cysts on imaging and distinct histological features (birbeck granules, S100 positive Langerhans cells), very different from the described tissue.
*Mature teratoma*
- A mature teratoma contains **tissues derived from all three germ layers**, such as hair, teeth, bone, and various epithelial linings.
- While it can contain cartilage and epithelium, the description of **disorganized hyaline cartilage interspersed with myxoid regions** in a lung nodule is most specific to a pulmonary hamartoma, not a widespread mixture of diverse mature tissues seen in a teratoma.
Question 13: A 72-year-old retired shipyard worker received a chest x-ray as part of a routine medical work-up. The radiologist reported incidental findings suggestive of an occupational lung disease. Which of the following descriptions is most consistent with this patient's film?
A. Hyperinflated lungs with a loss of lung markings
B. Enlarged hilar lymph nodes
C. Nodular calcium lesions in the apex of the lung
D. Fibrocalcific parietal pleural plaques on the diaphragm (Correct Answer)
E. No specific radiographic findings
Explanation: ***Fibrocalcific parietal pleural plaques on the diaphragm***
- A retired **shipyard worker** has a high likelihood of **asbestos exposure**, which often leads to the development of **pleural plaques**, especially on the diaphragm and parietal pleura.
- These plaques are **fibrocalcific** and are the most common radiographic manifestation of prior asbestos exposure, often found incidentally.
*Hyperinflated lungs with a loss of lung markings*
- This description is characteristic of **emphysema**, specifically the destruction of alveolar walls leading to air trapping and reduced vascular markings.
- While smoking could be common among shipyard workers, this finding does not directly indicate an **occupational lung disease** specific to asbestos exposure.
*Enlarged hilar lymph nodes*
- **Enlarged hilar lymph nodes** are a prominent feature in conditions like **sarcoidosis**, tuberculosis, or certain lymphomas.
- It is not a typical or specific finding for asbestos-related lung disease in the absence of other complications like malignancy.
*Nodular calcium lesions in the apex of the lung*
- **Nodular calcium lesions in the apex of the lung** are highly suggestive of **granulomatous disease**, most commonly **healed primary tuberculosis**.
- This finding is not directly associated with asbestos exposure or other common occupational lung diseases.
*No specific radiographic findings*
- A **chest x-ray** is highly effective in detecting significant asbestos-related changes due to their characteristic appearance.
- Given the patient's occupational history, the absence of specific findings would be less likely if there were any significant asbestos-related changes.
Question 14: A 66-year-old man presents with severe respiratory distress. He was diagnosed with pulmonary hypertension secondary to occupational pneumoconiosis. Biopsy findings of the lung showed ferruginous bodies. What is the most likely etiology?
A. Coal
B. Beryllium
C. Asbestos (Correct Answer)
D. Silica
E. Iron
Explanation: ***Asbestos***
- The presence of **ferruginous bodies** on lung biopsy is highly characteristic of **asbestosis**, which is caused by occupational exposure to asbestos fibers.
- Exposure to **asbestos** can lead to **pulmonary hypertension** due to the development of diffuse interstitial fibrosis and vascular remodeling.
*Coal*
- Exposure to **coal dust** causes **coal worker's pneumoconiosis** and can lead to progressive massive fibrosis but is not typically associated with ferruginous bodies as a defining marker.
- While coal dust can cause pulmonary hypertension, the specific biopsy finding of ferruginous bodies points away from coal as the primary etiology.
*Beryllium*
- **Berylliosis** is a granulomatous disease that can cause interstitial lung disease, but its characteristic histological finding is **non-caseating granulomas**, not ferruginous bodies.
- It is typically caused by exposure to beryllium, a light metal used in various industries.
*Silica*
- Exposure to **silica** causes **silicosis**, characterized by distinctive **fibrotic nodules** found predominantly in the upper lobes.
- While silicosis can also lead to pulmonary hypertension, it does not typically present with ferruginous bodies on histology.
*Iron*
- Exposure to **iron dust** can cause **siderosis**, a benign pneumoconiosis where iron particles accumulate in the lungs, but it generally does not cause significant fibrosis or pulmonary hypertension.
- Iron overload in the lung does not produce the characteristic ferruginous bodies observed in asbestos exposure.
Question 15: A 58-year-old man is brought to the emergency department after a witnessed tonic-clonic seizure. His wife says he has had a persistent dry cough for 6 months. During this time period, he has also had fatigue and a 4.5-kg (10-lb) weight loss. The patient has no history of serious illness and does not take any medications. He has smoked 1 pack of cigarettes daily for 35 years. He is confused and oriented only to person. Laboratory studies show a serum sodium concentration of 119 mEq/L and glucose concentration of 102 mg/dL. An x-ray of the chest shows an irregular, poorly demarcated density at the right hilum. Microscopic examination of this density is most likely to confirm which of the following diagnoses?
A. Squamous cell lung carcinoma
B. Large cell lung carcinoma
C. Bronchial carcinoid tumor
D. Small cell lung carcinoma (Correct Answer)
E. Lung adenocarcinoma
Explanation: ***Small cell lung carcinoma***
- The patient's **hyponatremia** and **seizure** are indicative of **syndrome of inappropriate antidiuretic hormone (SIADH)**, a common paraneoplastic syndrome associated with **small cell lung carcinoma (SCLC)**.
- The history of **heavy smoking**, **weight loss**, **fatigue**, **persistent cough**, and a **hilar mass** on chest X-ray are all classic presentations of SCLC.
*Squamous cell lung carcinoma*
- While strongly associated with smoking and often presenting as a hilar mass, it is more commonly linked to paraneoplastic syndromes like **hypercalcemia** due to PTHrP secretion, not SIADH.
- Seizures in this context would likely be secondary to metastatic brain lesions rather than severe hyponatremia from SIADH directly.
*Large cell lung carcinoma*
- This type of lung cancer is often diagnosed by exclusion, when other more specific types cannot be identified. It can present with a variety of symptoms, but it is less consistently associated with **SIADH** than SCLC.
- Tumors commonly grow rapidly and can present as large peripheral masses, though hilar involvement is also possible.
*Bronchial carcinoid tumor*
- These are typically **slow-growing neuroendocrine tumors** that are generally less aggressive than other lung cancers.
- While they can cause paraneoplastic syndromes like **Cushing's syndrome** or **carcinoid syndrome**, SIADH is not a common association, and the patient's rapidly progressing symptoms and significant weight loss point away from this diagnosis.
*Lung adenocarcinoma*
- This is the most common type of lung cancer in **non-smokers**, although it can occur in smokers. It often presents as a **peripheral lung mass** and is less commonly associated with **hilar masses**.
- While it can be associated with various paraneoplastic syndromes, **SIADH** is much less common compared to SCLC, and the clinical picture does not align as strongly.
Question 16: A 68-year-old man presents to the office with progressive shortness of breath and cough. A chest X-ray shows prominent hilar lymph nodes and scattered nodular infiltrates. Biopsy of the latter reveals noncaseating granulomas. This patient most likely has a history of exposure to which of the following?
A. Asbestos
B. Silica
C. Coal dust
D. Beryllium (Correct Answer)
E. Organic dust
Explanation: ***Beryllium***
- **Chronic beryllium disease** (CBD) is characterized by **noncaseating granulomas** in the lungs, similar to sarcoidosis, and is associated with occupational exposure to beryllium.
- Exposure typically occurs in workers involved in aerospace, ceramics, and electronics manufacturing.
*Asbestos*
- Exposure to **asbestos** is primarily associated with **asbestosis**, which features diffuse interstitial fibrosis, and an increased risk of mesothelioma and lung cancer.
- While it causes lung disease, it does not typically present with noncaseating granulomas as the primary pathological finding.
*Silica*
- **Silicosis** results from inhaling **crystalline silica** and is characterized by nodular opacities, often with “egg-shell” calcifications in hilar lymph nodes, and fibrotic nodules, but not noncaseating granulomas.
- The granulomas in silicosis are typically fibrotic and hyalinized, lacking the noncaseating appearance.
*Coal dust*
- Inhalation of **coal dust** leads to **coal worker's pneumoconiosis** (CWP), which can range from simple CWP with small nodular opacities to progressive massive fibrosis (PMF).
- The pathology involves **macrophage accumulation** laden with coal dust, leading to fibrosis, rather than forming noncaseating granulomas.
*Organic dust*
- Exposure to **organic dusts** (e.g., from molds, animal proteins, cotton) can lead to **hypersensitivity pneumonitis**, characterized by diffuse inflammation of the lung interstitium and airways.
- While granulomas can sometimes be seen in hypersensitivity pneumonitis, they are often poorly formed and are not the defining feature of the occupational lung disease that aligns with the described clinical picture with prominent nodular infiltrates and noncaseating granulomas, which is more characteristic of beryllium.
Question 17: A 61-year-old male presents to your office with fever and dyspnea on exertion. He has been suffering from chronic, non-productive cough for 1 year. You note late inspiratory crackles on auscultation. Pulmonary function tests reveal an FEV1/FVC ratio of 90% and an FVC that is 50% of the predicted value. Which of the following would you most likely see on a biopsy of this patient's lung?
A. Arteriovenous malformations
B. Hyaline membranes
C. Charcot-Leyden crystals
D. Subpleural cystic enlargement (Correct Answer)
E. Linear immunofluorescence along alveolar basement membranes
Explanation: ***Subpleural cystic enlargement***
- The patient's presentation with **dyspnea, non-productive cough, late inspiratory crackles**, and **restrictive lung disease** (normal FEV1/FVC ratio of 90% with reduced FVC of 50%) is highly suggestive of **pulmonary fibrosis**.
- **Subpleural cystic enlargement** (honeycombing) is the characteristic histological finding in advanced pulmonary fibrosis, particularly in the **usual interstitial pneumonia (UIP)** pattern seen in **idiopathic pulmonary fibrosis (IPF)**.
- The chronic, progressive nature (1-year history) and the restrictive PFT pattern make this the most likely biopsy finding.
*Arteriovenous malformations*
- These are abnormal vascular connections between arteries and veins that can cause **hypoxemia** and are typically associated with **hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu disease)**.
- They do not explain the restrictive PFT pattern or the typical presentation of chronic progressive fibrosis with late inspiratory crackles.
*Linear immunofluorescence along alveolar basement membranes*
- This finding on **direct immunofluorescence** with **IgG deposition** is characteristic of **Goodpasture syndrome** (anti-GBM disease), which causes pulmonary hemorrhage and rapidly progressive glomerulonephritis.
- This condition presents with **hemoptysis** and **acute renal failure**, not chronic non-productive cough, and would show an obstructive or mixed pattern if hemorrhage were present.
*Hyaline membranes*
- **Hyaline membranes** are proteinaceous material lining alveoli seen in **acute respiratory distress syndrome (ARDS)** or **diffuse alveolar damage (DAD)**.
- The patient's **chronic 1-year symptoms** and restrictive PFTs indicate chronic interstitial lung disease, not acute lung injury.
*Charcot-Leyden crystals*
- **Charcot-Leyden crystals** are formed from breakdown of **eosinophils** and are found in conditions with eosinophilic inflammation, such as **asthma** or **eosinophilic pneumonia**.
- While these conditions can cause cough and dyspnea, they would typically show an **obstructive pattern** (reduced FEV1/FVC) in asthma, not the restrictive pattern seen here.
Question 18: A 58-year-old woman presents to the physician with a cough that began 6 years ago, as well as intermittent difficulty in breathing for the last year. There is no significant sputum production. There is no history of rhinorrhea, sneezing or nose congestion. She has been a chronic smoker from early adulthood. Her temperature is 36.9°C (98.4°F), the heart rate is 80/min, the blood pressure is 128/84 mm Hg, and the respiratory rate is 22/min. A physical examination reveals diffuse end-expiratory wheezing with prolonged expiration on chest auscultation; breath sounds and heart sounds are diminished. There is no cyanosis, clubbing or lymphadenopathy. Her chest radiogram shows hyperinflated lungs bilaterally and a computed tomography scan of her chest is shown in the picture. Which of the following best describes the pathogenesis of the condition of this patient?
A. Structural cell death mediated by Rtp801
B. Activation of histone deacetylase-2
C. Depletion of the periciliary fluid layer in airway cells
D. Infiltration of the lower airway mucosa by activated eosinophils and T lymphocytes
E. Increased release of matrix metalloproteinase 12 (MMP-12) by macrophages (Correct Answer)
Explanation: ***Increased release of matrix metalloproteinase 12 (MMP-12) by macrophages***
- The patient's presentation with **chronic cough**, **dyspnea**, **wheezing**, **prolonged expiration**, **hyperinflated lungs**, and a history of **chronic smoking** is highly suggestive of **emphysema**, a form of COPD.
- **Emphysema** is characterized by the destruction of alveolar walls, primarily driven by an imbalance between proteases and antiproteases, where **MMP-12** (also known as macrophage elastase) released by **macrophages** plays a critical role in degrading **elastin** and other components of the extracellular matrix.
- Cigarette smoke activates alveolar macrophages, which release MMP-12 that destroys elastin fibers in alveolar walls, leading to the characteristic airspace enlargement and loss of elastic recoil.
*Structural cell death mediated by Rtp801*
- **Rtp801** has been implicated in **apoptosis** and cellular stress responses, particularly in the context of chronic kidney disease and other inflammatory conditions.
- While cellular stress and death contribute to lung pathology, **Rtp801** is not considered the primary or defining pathogenic mechanism for the extensive alveolar destruction seen in emphysema.
*Activation of histone deacetylase-2*
- **Histone deacetylase-2 (HDAC2)** is crucial for the anti-inflammatory effects of corticosteroids; its **reduced activity** in COPD contributes to corticosteroid resistance.
- However, **activation** of **HDAC2** would typically mitigate inflammation, which is contrary to the ongoing inflammatory and destructive processes in COPD.
*Depletion of the periciliary fluid layer in airway cells*
- **Depletion of the periciliary fluid layer** is a characteristic feature of **cystic fibrosis**, leading to impaired mucociliary clearance and recurrent infections.
- This mechanism is not the primary driver of alveolar destruction and airway obstruction seen in **emphysema**.
*Infiltration of the lower airway mucosa by activated eosinophils and T lymphocytes*
- While inflammatory cells are involved in COPD, significant **eosinophilic infiltration** is more characteristic of **asthma** or certain subtypes of COPD with an asthmatic component.
- The primary inflammatory cells in typical **emphysema** are **neutrophils**, **macrophages**, and **CD8+ T-lymphocytes**.
Question 19: A 32-year-old man comes to the physician for a 1-month history of fever, chest pain with deep breathing, and a 4-kg (9 lb) weight loss. His temperature is 38°C (100.4°F). An x-ray of the chest shows a subpleural nodule in the right lower lobe with right hilar lymphadenopathy. Histological examination of a right hilar lymph node biopsy specimen shows several granulomas with acellular cores. Which of the following is the most likely diagnosis?
A. Primary tuberculosis (Correct Answer)
B. Hodgkin lymphoma
C. Chronic berylliosis
D. Miliary tuberculosis
E. Pulmonary sarcoidosis
Explanation: ***Primary tuberculosis***
- The combination of **fever**, **chest pain with deep breathing**, **weight loss**, a **subpleural nodule**, **right hilar lymphadenopathy**, and **granulomas with acellular cores** on biopsy strongly points to primary tuberculosis.
- Granulomas in tuberculosis are typically **caseating** (acellular cores often imply caseating necrosis in this context), and the presence of hilar lymphadenopathy with a peripheral nodule (Ghon complex) is classic for primary infection.
*Hodgkin lymphoma*
- While Hodgkin lymphoma can cause fever, weight loss (B symptoms), and lymphadenopathy, the presence of a **subpleural nodule** and **granulomas with acellular cores** is not typical.
- Histology would show **Reed-Sternberg cells** amidst a mixed inflammatory infiltrate, not granulomas with acellular cores.
*Chronic berylliosis*
- This condition is caused by **beryllium exposure** and typically presents with a history of occupational exposure and **non-caseating granulomas**.
- No history of beryllium exposure is provided, and the granulomas described are consistent with **caseating necrosis** (acellular cores).
*Miliary tuberculosis*
- Miliary tuberculosis involves widespread dissemination, often presenting with **diffuse, small nodules** (millet seed-sized) across both lungs on X-ray, rather than a single subpleural nodule and hilar lymphadenopathy.
- While it features granulomas, the **radiological pattern** is distinct.
*Pulmonary sarcoidosis*
- Sarcoidosis is characterized by **non-caseating granulomas** in multiple organs, often presenting with bilateral hilar lymphadenopathy and pulmonary involvement.
- The description of **acellular cores** suggests **caseating granulomas**, which are not typical of sarcoidosis.
Question 20: An investigator is studying the effects of influenza virus on human lung tissue. Biopsy specimens of lung parenchyma are obtained from patients recovering from influenza pneumonia and healthy control subjects. Compared to the lung tissue from the healthy control subjects, the lung tissue from the affected patients is most likely to show which of the following findings on histopathologic examination?
A. Decreased alveolar macrophages
B. Increased goblet cells
C. Decreased interstitial fibroblasts
D. Increased alveolar squamous epithelial cells
E. Increased type II pneumocytes (Correct Answer)
Explanation: ***Increased type II pneumocytes***
- **Type II pneumocytes** are responsible for producing **surfactant** and act as **progenitor cells** for **type I pneumocytes**.
- In response to injury, like that caused by **influenza pneumonia**, type II pneumocytes proliferate to replace damaged type I pneumocytes and repair the alveolar epithelium.
*Decreased alveolar macrophages*
- **Alveolar macrophages** are immune cells that **phagocytose** pathogens and cellular debris in the alveoli.
- In an active infection like **influenza pneumonia**, their numbers would likely be **increased** due to their role in immune response, not decreased.
*Increased goblet cells*
- **Goblet cells** are found in the larger airways and are responsible for **mucus production**.
- While respiratory infections can increase mucus production, the question specifies **lung parenchyma** (alveoli) where goblet cells are not typically found.
*Decreased interstitial fibroblasts*
- **Interstitial fibroblasts** contribute to the structural integrity of the lung and can differentiate into **myofibroblasts** during repair and fibrosis.
- In the context of pneumonia and potential repair processes, fibroblast activity might be altered, but a decrease is unlikely given their role in tissue remodeling, and an increase might be seen in the context of **fibrosis**.
*Increased alveolar squamous epithelial cells*
- **Alveolar squamous epithelial cells** are **type I pneumocytes**, which form the primary gas-exchange surface.
- **Influenza pneumonia** causes damage and destruction of type I pneumocytes, meaning their numbers would be **decreased**, not increased.
