Viral Pneumonia

Viral Pneumonia

Jud W. Gurney, MD, FACR

Axial NECT shows centrilobular nodules image with indistinct ground-glass edges. Note the faint tree-in-bud opacities in the left upper lobe image.

Axial NECT shows centrilobular nodules image admixed with ground-glass opacities image in this patient with community-acquired pneumonia from viral pneumonia.


Abbreviations and Synonyms

  • Cytomegalovirus (CMV), severe acute respiratory syndrome (SARS), Epstein-Barr virus (EBV)


  • Pulmonary infection with viral pathogen, typically affects respiratory epithelium from trachea to terminal bronchioles

    • Pneumonic (alveolar involvement) less common but often severe and rapidly progressive


General Features

  • Best diagnostic clue: Centrilobular nodules and ground-glass opacities in peribronchial distribution

  • Patient position/location: Peribronchial centrilobular nodules

  • Size: Centrilobular nodules 4-10 mm in diameter

  • Morphology: Centrilobular nodules in patchy distribution most helpful finding to distinguish infectious vs. noninfectious disease

CT Findings

  • Variable and nonspecific appearance

  • Bronchiolitis (small airways involvement)

    • Centrilobular nodules

      • 4-10 mm in diameter, may be miliary

      • Patchy peribronchial distribution

      • Ill-defined edges, may have ground-glass halos

      • Usually associated with background of ground-glass opacities

      • Pathologic correlate: Viral involvement of terminal airways

    • Mosaic attenuation (correlate of hyperinflation)

    • Tree-in-bud opacities less common than in bacterial pneumonia

  • Tracheobronchitis (larger airways involvement)

    • Bronchial wall thickening

    • Segmental consolidation

  • Pneumonic (lung involvement)

    • Consolidation and ground-glass opacities

      • Pathologic correlate: Noncardiogenic pulmonary edema or diffuse hemorrhage

    • Distribution: Focal or diffuse

    • Thickened interlobular septa

  • Course

    • Insidious: Slow development over 7-14 days

      • Primary pattern: Centrilobular nodules

    • Fulminant: Rapid progressive disease

      • Primary pattern: Diffuse ground-glass opacities and consolidation

    • Late: Bronchiolitis obliterans

      • Pathologic correlate: Healed response to damage of small airways

      • Uncommon, lung usually returns to normal

Radiographic Findings

  • Radiography

    • Variable and overlapping appearance

    • Tracheobronchitis

      • Often normal

      • Segmental opacities (from airway obstruction or pneumonia)

      • Atelectasis: Discoid to segmental atelectasis (from mucus plugs)

    • Bronchiolitis

      • Vague small nodular opacities, patchy distribution

      • Bronchial wall thickening

      • Hyperinflation (less common in adults than in children)

    • Pneumonia

      • Diffuse consolidation from noncardiac edema or hemorrhage, normal heart size

      • Pleural effusions, if present, small

    • Complications

      • Bacterial superinfection; consider if sudden worsening, development of cavitation, or enlarging pleural effusion

    • Uncommon findings

      • Hilar or mediastinal adenopathy: Measles (in children), EBV (infectious mononucleosis)

    • Splenomegaly

      • EBV (infectious mononucleosis)

    • Cardiac enlargement from pericardial effusion

      • Hantavirus

    • Pleural effusions

      • Rare except for adenovirus, measles, hantavirus, herpes simplex type 1

Imaging Recommendations

  • Best imaging tool

    • Chest radiography: Usually sufficient for documenting pattern and extent of disease and monitoring therapy

    • CT: More sensitive; important in immunocompromised patients to document disease and begin early treatment


Hypersensitivity Pneumonitis

  • Farmer’s lung often mistaken for pneumonia: Tends to be recurrent with repeated exposure to offending antigen

  • May also be febrile

Bacterial Pneumonia

  • Patchy centrilobular nodules more common in viral or atypical pneumonias

  • Culture required for management

Sep 20, 2016 | Posted by in RESPIRATORY IMAGING | Comments Off on Viral Pneumonia

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