Pulmonary Infections — MCQs

10 questions

Air bronchogram on chest X-ray denotes -

Which of the following features is NOT typically seen in viral pneumonia?

A 6-year-old boy presents with fever and chills, cough, rapid breathing, difficulty breathing, and chest pain. A culture from a respiratory sample shows Gram-positive bacteria. What is the most likely organism causing this infection?

In primary tuberculosis, what is seen?

A 50-year-old male with hemoptysis shows cavitary lesion with air-crescent sign. Most likely diagnosis?

A 40-year-old with HIV presents with fever, cough, and hypoxia. Chest X-ray shows bilateral infiltrates. What is the most likely diagnosis?

Which condition is characterized by a specific appearance on CT scans that resembles small centrilobular nodules with branching linear structures?

A 65-year-old male presents with fever, chills, and a productive cough with rust-colored sputum. What is the most likely diagnosis?

Which of the following conditions characteristically causes bilateral hypertranslucency of lung fields on chest X-ray?

Q10

Identify the most likely diagnosis based on the chest X-ray findings in a patient with low-grade fever.

Pulmonary Infections Indian Medical PG Practice Questions and MCQs

Question 1: Air bronchogram on chest X-ray denotes -

A. Intrapulmonary lesion (Correct Answer)
B. Extrapulmonary lesion
C. Intrathoracic lesion
D. Extrathoracic lesion

Explanation: ***Intrapulmonary lesion*** - An **air bronchogram** indicates that the air-filled bronchi are surrounded by consolidated or fluid-filled alveoli, making the bronchi visible against the opacified lung parenchyma. - This pattern is a strong sign of a process **within the lung tissue itself**, such as pneumonia, pulmonary edema, or malignancy. *Extrapulmonary lesion* - **Extrapulmonary lesions**, such as pleural effusions or masses originating from the chest wall, typically displace or compress the lung and bronchi, rather than filling the alveoli around them. - They usually do **not produce an air bronchogram** because the air in the bronchi is not juxtaposed against diseased lung parenchyma. *Intrathoracic lesion* - This is a broad term that includes all lesions within the thoracic cavity, both intrapulmonary and extrapulmonary. - While an air bronchogram is an intrathoracic finding, it specifically points to an **intrapulmonary process**, not just any intrathoracic lesion. *Extrathoracic lesion* - **Extrathoracic lesions** are located outside the chest cavity and would not manifest as an air bronchogram on a chest X-ray. - This option is **completely unrelated** to the interpretation of an air bronchogram.

Question 2: Which of the following features is NOT typically seen in viral pneumonia?

A. Bronchiolitis
B. Multinucleate giant cells in the bronchiolar wall
C. Predominance of alveolar exudate (Correct Answer)
D. Presence of interstitial inflammation

Explanation: ### Predominance of alveolar exudate - Viral pneumonia typically involves the **interstitium**, leading to interstitial inflammation, rather than a significant accumulation of **exudate** within the alveoli [3]. - **Alveolar exudate** is more characteristic of **bacterial pneumonia**, where neutrophils and fibrin fill the alveolar spaces [1], [2], [3]. ### Presence of interstitial inflammation - This is a **hallmark pathological feature** of viral pneumonia, where inflammatory cells infiltrate the alveolar septa and peribronchial tissues [3]. - The inflammation primarily involves the **walls of the alveoli** and the **surrounding connective tissue**, not the alveolar lumen. ### Bronchiolitis - Viral infections, especially in children, often affect the **small airways (bronchioles)**, causing inflammation and obstruction. - This can lead to symptoms such as **wheezing** and **dyspnea** in viral pneumonia. ### Multinucleate giant cells in the bronchiolar wall - The presence of **multinucleate giant cells** is a specific histological finding associated with certain viral pneumonias, particularly those caused by **measles** and **respiratory syncytial virus (RSV)**. - These cells arise from the fusion of infected cells and are found within the bronchiolar epithelium and lumen. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 317-318. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 711-712. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, p. 715.

Question 3: A 6-year-old boy presents with fever and chills, cough, rapid breathing, difficulty breathing, and chest pain. A culture from a respiratory sample shows Gram-positive bacteria. What is the most likely organism causing this infection?

A. Streptococcus pyogenes
B. Streptococcus pneumoniae (Correct Answer)
C. Staphylococcus aureus
D. Propionibacterium acnes

Explanation: ***Streptococcus pneumoniae*** - This clinical picture describes typical symptoms of **pneumonia** in a child, including fever, cough, rapid and difficult breathing, and chest pain. - **_Streptococcus pneumoniae_** is the most common bacterial cause of community-acquired pneumonia in children. The respiratory sample showing gram-positive bacteria further supports this. *Staphylococcus aureus* - While **_Staphylococcus aureus_** can cause pneumonia, it is less common than _Streptococcus pneumoniae_ in community-acquired cases in healthy children and often associated with more severe, necrotizing forms or post-viral infections. - While it is a **Gram-positive bacterium**, its clinical presentation would not be the most likely first choice for typical pneumonia symptoms in this age group. *Propionibacterium acnes* - **_Propionibacterium acnes_** (now *Cutibacterium acnes*) is primarily associated with **acne vulgaris** and, less commonly, opportunistic infections related to implanted devices or some rare soft tissue infections. - It is not a typical cause of primary respiratory infections like pneumonia. *Streptococcus pyogenes* - **_Streptococcus pyogenes_** (Group A Streptococcus) is known for causing **pharyngitis** (strep throat), skin infections (impetigo, cellulitis), and scarlet fever. - While it can rarely cause pneumonia, it is not a common cause, and the constellation of symptoms points more strongly to _Streptococcus pneumoniae_.

Question 4: In primary tuberculosis, what is seen?

A. Ghon's focus (Correct Answer)
B. Pleural effusion
C. Miliary mottling
D. Fibrosis

Explanation: ***Ghon's focus*** - A **Ghon's focus** is the primary parenchymal lesion that develops at the site of initial infection in **primary tuberculosis**. - It consists of a small area of caseous necrosis in the lung parenchyma, typically in the **mid or lower zones**. - Combined with hilar lymph node involvement, it forms the **Ghon complex (primary complex)**, which is the pathological hallmark of primary TB. - This represents the **characteristic pathological finding** that defines primary tuberculosis [2]. *Pleural effusion* - **Pleural effusion** is actually a **common manifestation of primary tuberculosis**, particularly in adolescents and adults [3]. - It develops due to a hypersensitivity reaction to tubercular antigens in the pleural space. - While frequently seen in primary TB, it is a **clinical manifestation** rather than the defining pathological lesion (Ghon's focus). - Can occur in both primary and post-primary TB [3]. *Miliary mottling* - **Miliary mottling** on chest X-ray is characteristic of **miliary tuberculosis**, a severe form where the infection disseminates hematogenously [1]. - This represents a **complication of primary TB** due to lymphohematogenous spread, not the typical presentation [1]. - Shows multiple small nodules (1-3mm) scattered throughout both lung fields. *Fibrosis* - **Fibrosis** refers to scarring of lung tissue that occurs during the **healing phase** of tuberculosis. - It is a **sequela of TB infection**, not an acute finding in primary tuberculosis. - Develops after the active infection has been controlled or treated [1]. **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. 379-380. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 728-729.

Question 5: A 50-year-old male with hemoptysis shows cavitary lesion with air-crescent sign. Most likely diagnosis?

A. Tuberculosis
B. Aspergilloma (Correct Answer)
C. Granulomatosis with polyangiitis (GPA)
D. Lung abscess

Explanation: ***Aspergilloma*** - The presence of a **cavitary lesion** with an **air-crescent sign** (Monod sign) in a patient with hemoptysis is highly characteristic of an aspergilloma, which is a fungal ball growing within a pre-existing lung cavity. - **Hemoptysis** is a common symptom due to the erosion of vessels by the fungal ball or inflammation. *Tuberculosis* - While **cavitary lesions** can be seen in tuberculosis, the **air-crescent sign** is not typical and hemoptysis in TB is usually related to active infection or rupture of an aneurysm (Rasmussen's aneurysm). - Tuberculosis would typically show other features like **consolidation**, **lymphadenopathy**, or **miliary opacities** depending on the stage. *Granulomatosis with polyangiitis (GPA)* - GPA can cause **cavitary lung lesions** and **hemoptysis** due to parenchymal vasculitis. - However, it does not typically present with the definitive **air-crescent sign** seen with aspergilloma. GPA would also show signs of **renal involvement** and **upper airway disease**. *Lung abscess* - A lung abscess is a **pus-filled cavity** in the lung often caused by bacterial infection, appearing as a cavitary lesion in imaging. - While it can cause hemoptysis, the **air-crescent sign** is not a characteristic feature; instead, it typically shows a **thick, irregular wall** with an air-fluid level.

Question 6: A 40-year-old with HIV presents with fever, cough, and hypoxia. Chest X-ray shows bilateral infiltrates. What is the most likely diagnosis?

A. Lung abscess
B. Bacterial pneumonia
C. Pneumocystis pneumonia (Correct Answer)
D. Tuberculosis

Explanation: ***Pneumocystis pneumonia*** - In an HIV-positive individual with **fever**, **cough**, **hypoxia**, and **bilateral infiltrates** on chest X-ray, *Pneumocystis jirovecii* pneumonia (PCP) is the most common and likely opportunistic infection to consider [1]. - PCP typically presents with **progressive dyspnea** and a **diffuse interstitial pattern** on imaging, consistent with the bilateral infiltrates described [1]. *Lung abscess* - A **lung abscess** is typically characterized by a **cavitary lesion** on chest X-ray, which is not mentioned in the patient's presentation. - While it can cause fever and cough, severe hypoxia and bilateral infiltrates in this context are less suggestive of an abscess as the primary diagnosis. *Bacterial pneumonia* - **Bacterial pneumonia** often presents with **lobar or segmental consolidation** on chest X-ray, rather than diffuse bilateral infiltrates [1][2]. - While possible, the clinical picture in an HIV patient with severe hypoxia and diffuse infiltrates points more strongly towards an atypical pneumonia like PCP [1]. *Tuberculosis* - **Tuberculosis** in immunocompromised individuals can present with atypical patterns, but classic active TB often involves **upper lobe cavitations** or **lymphadenopathy** [1]. - While present in HIV patients, the acute onset of severe hypoxia and diffuse infiltrates is less characteristic of primary or reactivation TB, which often has a more indolent course [1].

Question 7: Which condition is characterized by a specific appearance on CT scans that resembles small centrilobular nodules with branching linear structures?

A. Pulmonary tuberculosis (Correct Answer)
B. Silicosis
C. Pulmonary hydatid cyst
D. Small cell carcinoma

Explanation: ***Pulmonary tuberculosis*** - This description ("small centrilobular nodules with **branching linear structures**") is characteristic of the **tree-in-bud pattern** seen on CT scans, which is a hallmark finding in active **endobronchial spread of tuberculosis**. - The tree-in-bud pattern results from the impaction of tuberculous **granulomas** and caseous material in the terminal and respiratory bronchioles. *Silicosis* - Characterized by multiple small, well-defined **nodules** (often in the upper lobes) that tend to calcify, but typically lacks the fine **branching linear structures**. - It’s associated with occupational exposure to **silica dust** and may progress to **massive progressive fibrosis**. *Pulmonary hydatid cyst* - Presents as a well-defined, usually **single, large cystic lesion** on CT, often with internal membranes if ruptured (water lily sign or crumpled membrane sign). - It does not typically manifest with small centrilobular nodules or branching linear structures. *Small cell carcinoma* - Usually appears as a **large central mass**, often with mediastinal lymphadenopathy, and sometimes associated with obstructive pneumonitis. - It does not typically present as diffuse small centrilobular nodules with branching patterns.

Question 8: A 65-year-old male presents with fever, chills, and a productive cough with rust-colored sputum. What is the most likely diagnosis?

A. TB
B. Klebsiella pneumonia
C. Pneumocystis pneumonia
D. Pneumococcal Pneumonia (Correct Answer)

Explanation: Pneumococcal Pneumonia - This presentation with fever, chills, and rust-colored sputum is classic for pneumococcal pneumonia, caused by Streptococcus pneumoniae [1]. [2] - The rust color results from the presence of hemolyzed red blood cells from the inflamed alveoli [3]. TB - While TB can cause fever and cough, the sputum is typically mucoid or purulent, and sometimes hemoptysis (frank blood) is seen, but not usually rust-colored [4]. - TB symptoms tend to be more chronic, including night sweats and weight loss, which are not mentioned here. Klebsiella pneumonia - Klebsiella pneumoniae typically causes severe pneumonia, often in individuals with alcoholism or diabetes [1]. - It classically presents with currant jelly sputum, which is distinct from rust-colored sputum [2]. Pneumocystis pneumonia - Pneumocystis jirovecii pneumonia (PCP) primarily affects immunocompromised individuals, particularly those with HIV [4]. - Symptoms are usually more insidious, involving dyspnea, non-productive cough, and hypoxia, and sputum is not typically rust-colored [4].

Question 9: Which of the following conditions characteristically causes bilateral hypertranslucency of lung fields on chest X-ray?

A. Mcleod syndrome
B. Poland syndrome
C. Emphysema (Correct Answer)
D. Pneumothorax

Explanation: ***Correct: Emphysema*** - **Emphysema** causes destruction of alveolar walls, leading to enlarged air spaces and **air trapping**, making both lungs appear hypertranslucent on X-ray - This **bilateral hypertranslucency** is due to reduced lung tissue density, decreased vascular markings, and increased air volume - Classic radiographic features include flattened diaphragms, increased retrosternal space, and hyperlucent lung fields *Incorrect: Mcleod syndrome* - Also known as **Swyer–James–MacLeod syndrome**, this condition causes **unilateral** lung or lobe hyperlucency due to post-infectious obliterative bronchiolitis - The key differentiating feature is that it's **unilateral**, whereas the question asks for bilateral hypertranslucency - Affected lung shows air trapping on expiratory films *Incorrect: Pneumothorax* - A **pneumothorax** presents as a **unilateral** or focal hypertranslucent area due to air in the pleural space - Characterized by **absence of lung markings** beyond the visceral pleural line and associated lung collapse - This is a pleural space abnormality, not a bilateral parenchymal lung disease *Incorrect: Poland syndrome* - **Poland syndrome** is a congenital condition with absence or underdevelopment of the pectoralis major muscle - Can lead to **unilateral** apparent hyperlucency on the affected side due to missing chest wall muscle - This is a **chest wall anomaly**, not a parenchymal lung disease causing bilateral hypertranslucency

Question 10: Identify the most likely diagnosis based on the chest X-ray findings in a patient with low-grade fever.

A. ILD
B. Bronchopneumonia
C. Miliary TB (Correct Answer)
D. Consolidation

Explanation: ***Miliary TB*** - The chest X-ray shows diffuse, small, uniformly distributed nodular opacities (2-3 mm in diameter) bilaterally, characteristic of "**millet seed**" pattern seen in **miliary tuberculosis**. - This pattern results from the hematogenous spread of *Mycobacterium tuberculosis* throughout the lungs, often presenting with **low-grade fever** and constitutional symptoms. *ILD* - **Interstitial lung disease (ILD)** typically shows reticular, nodular, or ground-glass opacities, sometimes with honeycombing, but the pattern is usually more heterogeneous and often basal or peripheral, unlike the uniform fine nodularity seen here. - While some ILDs can present with diffuse nodular patterns, the clinical context of **fever** and the classic "millet seed" appearance are more indicative of miliary TB. *Bronchopneumonia* - **Bronchopneumonia** presents as patchy, often ill-defined, multifocal areas of opacification or consolidation, usually distributed around the bronchi. - It does not typically cause the fine, diffuse, and uniform nodular pattern seen in this image, which represents widespread interstitial or alveolar involvement rather than primarily bronchial inflammation. *Consolidation* - **Consolidation** appears as a homogeneous opacification that obliterates vessels and airway walls, often with air bronchograms, typically confined to a lobe or segment. - The image shows diffuse nodular infiltrates rather than large, confluent areas of homogeneous opacification, making isolated consolidation an unlikely primary description.

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