Nonspecific Interstitial Pneumonia

Nonspecific Interstitial Pneumonia

Jud W. Gurney, MD, FACR

Tan-Lucien H. Mohammed, MD, FCCP

Axial NECT shows peribronchial peripheral ground-glass opacities image, which exceed reticular opacities. Note the subpleural sparing image.

Coronal NECT shows basilar fan-shaped image ground-glass and reticular opacities extending along the bronchovascular pathways. Subpleural sparing image is noted in this patient with NSIP.


Abbreviations and Synonyms

  • Nonspecific interstitial pneumonia (NSIP)


  • 1 of the idiopathic interstitial pneumonias, less common than idiopathic pulmonary fibrosis (IPF), but with better prognosis than IPF

    • Distinguished by temporal and spatial uniformity of histologic findings


General Features

  • Best diagnostic clue: Traction bronchiectasis out of proportion to reticular opacities

  • Patient position/location: Peribronchovascular basilar distribution

  • Size: Generally involves 25-35% of lung volume

  • Morphology: Ground-glass opacities > reticular opacities

CT Findings

  • Morphology

    • Reticular opacities (85%)

      • Often admixed with ground-glass opacities

      • Ground-glass opacities, when present, usually exceed reticular opacities

      • Combined ground-glass opacities and reticular opacities may result in crazy-paving pattern

    • Traction bronchiectasis (80%)

      • Often out of proportion to degree of reticular opacities

      • Usually associated with considerable lobar volume loss

      • Mean 20% of total lung volume

    • Ground-glass opacities (75%)

      • Ground-glass opacities often exceed reticular opacities, especially early

      • Mean 25-35% of lung volume with ground-glass opacities

      • May have mosaic perfusion pattern (5%)

    • Peribronchial thickening (5%)

    • Honeycombing rare (5%) (so uncommon, should suggest usual interstitial pneumonitis [UIP])

      • May have fine honeycombing: Microcystic honeycombing

      • Isolated enlarged airspaces may be present (not clustered together like honeycombing)

    • Consolidation less common, mean 10% of lung volume

  • Distribution

    • Symmetry common

    • Craniocaudad

      • Lower (92%)

      • Diffuse (8%)

    • Axial

      • Diffuse (60%)

      • Peripheral (35%)

    • Subpleural sparing (20%)

      • Very thin rim

    • Bronchovascular distribution, often fan-shaped from hilum to lung periphery

  • Evolution

    • Up to 30% over 3-year period evolve to more UIP pattern

    • Reversible findings: Ground-glass opacities, reticular opacities, traction bronchiectasis

  • Adenopathy (80%)

    • Mediastinal lymph node enlargement < 2 cm short axis diameter

    • Most common location right paratracheal nodal station (American Thoracic Society [ATS] region 4) or subcarinal (ATS region 7)

    • Direct positive correlation between extent of parenchymal involvement and presence of lymphadenopathy

  • Accuracy

    • Should make confident diagnosis in 80% of cases

    • Positive predictive value of confident diagnosis = 70-80%

Radiographic Findings

  • Radiography

    • Radiography: Nonspecific, abnormal (90%)

    • Bibasilar interstitial thickening (“lace-like” honeycombing)

Imaging Recommendations

  • Best imaging tool: HRCT to detect and characterize interstitial lung disease


Idiopathic Pulmonary Fibrosis (IPF)

  • Honeycombing more common

  • Subpleural peripheral location, more common

    • No subpleural sparing

  • Ground-glass extent less common

  • Histopathology: Temporal inhomogeneity of lung injury

  • Poorer prognosis than NSIP

Hypersensitivity Pneumonitis

  • May have NSIP pattern

  • Occupational and home environmental history extremely important to discover known antigens

  • Mosaic perfusion pattern more common

  • Chronic disease usually more severe in mid and upper lung zones, honeycombing more common

Cryptogenic Organizing Pneumonia (COP)

  • Consolidation usually more prominent than in NSIP

  • May have multiple pulmonary nodules or single mass, uncommon with NSIP

  • Reverse halo sign not seen with NSIP

  • Reticular opacities uncommon but similar to NSIP

Desquamative Interstitial Pneumonia (DIP)

  • Smokers; smoking less common in NSIP

  • Diffuse ground-glass opacities with scattered cysts

  • Traction bronchiectasis uncommon

Pulmonary Alveolar Proteinosis (PAP)

  • “Crazy-paving” appearance, less common with NSIP

  • Central and geographic distribution, not bronchovascular or peripheral

  • No traction bronchiectasis


  • Nodules: Most common pattern follows lymphatic pathways

    • Centrilobular, bronchovascular, and subpleural

  • Occasionally have predominant ground-glass opacities

    • Would not be associated with traction bronchiectasis if ground-glass opacities were predominant pattern

  • Adenopathy more common and nodes larger, especially in early disease

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

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