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Viral pneumonias in adults: radiologic and pathologic findings
Eun A Kim1, Kyung Soo Lee, Steven L Primack
1Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-Dong, Kangnam-Ku, Seoul 135-710, Korea.
Abstract:
Numerous viruses, including influenza virus, measles virus, Hantavirus, adenovirus, herpesviruses, varicella-zoster virus, cytomegalovirus, and Epstein-Barr virus, can cause lower respiratory tract infection in adults. Viral pneumonia in adults can be classified into two clinical groups: so-called atypical pneumonia in otherwise healthy hosts and viral pneumonia in immunocompromised hosts. Influenza virus types A and B cause most cases of viral pneumonia in immunocompetent adults. Immunocompromised hosts are susceptible to pneumonias caused by cytomegalovirus, herpesviruses, measles virus, and adenovirus. The radiographic findings, which consist mainly of patchy or diffuse ground-glass opacity with or without consolidation and reticular areas of increased opacity, are variable and overlapping. Computed tomographic findings, which are also overlapping, consist of poorly defined centrilobular nodules, ground-glass attenuation with a lobular distribution, segmental consolidation, or diffuse ground-glass attenuation with thickened interlobular septa. The radiologic findings reflect the variable extents of the histopathologic features: diffuse alveolar damage (intraalveolar edema, fibrin, and variable cellular infiltrates with a hyaline membrane), intraalveolar hemorrhage, and interstitial (intrapulmonary or airway) inflammatory cell infiltration. Clinical information such as patient age, immune status, community outbreaks, symptom onset and duration, and presence of a rash remain important aids in diagnosis of viral causes.
Insights
Viral pneumonia in adults, caused by various viruses like influenza, can present as atypical pneumonia or in immunocompromised individuals. Diagnosis relies on clinical data and overlapping radiographic findings.
Area of Science:
- Virology
- Pulmonology
- Radiology
Background:
- Numerous viruses, including influenza, measles, and herpesviruses, cause lower respiratory tract infections in adults.
- Viral pneumonia is categorized into atypical pneumonia in healthy individuals and pneumonia in immunocompromised hosts.
- Influenza viruses A and B are primary causes in immunocompetent adults, while cytomegalovirus and herpesviruses affect immunocompromised patients.
Purpose of the Study:
- To review the viral causes of lower respiratory tract infections in adults.
- To discuss the clinical classification and diagnostic features of viral pneumonia.
- To highlight the role of imaging and clinical information in diagnosing viral pneumonia.
Main Methods:
- Literature review of viral etiologies for lower respiratory tract infections.
- Analysis of clinical classifications of viral pneumonia.
- Examination of radiographic and computed tomographic (CT) findings.
- Correlation of radiologic findings with histopathologic features.
Main Results:
- Radiographic findings include patchy or diffuse ground-glass opacity, consolidation, and reticular opacities.
- CT scans show poorly defined nodules, ground-glass attenuation, consolidation, and thickened septa.
- Histopathology reveals diffuse alveolar damage, hemorrhage, and inflammatory infiltrates.
- Clinical factors like age, immune status, and symptom onset aid in diagnosis.
Conclusions:
- Viral pneumonia presents with variable and overlapping imaging findings.
- Accurate diagnosis requires integrating clinical information with radiologic evidence.
- Understanding viral pathogens and their associated pneumonia patterns is crucial for patient management.