Interstitial Pneumonias

General

  • There are 3 levels when we talk about the IP

    • The actual pattern we see on imaging (morphological pattern) - i.e. UIP

    • The diagnosis that we give that pattern (clinical diagnosis) - i.e. IPF

    • And the conditions we need to be aware of that may present this way (associated conditions) - i.e. Scleroderma

  • Morphologic patterns

    • Usual IP

    • Nonspecific IP

    • Desquamative IP

    • Lymphoid IP

  • UIP ~ 50% of all IP cases

  • Types

    • Fibrosing

      • Usual Interstitial Pneumonia

      • Nonspecific Interstitial Pneumonia

      • Chronic hypersensitivity pneumonitis

      • Idiopathic pleuropulmonary fibroelastosis

    • Smoking Related Diseases

      • Respiratory Bronchoiolitis

      • Respiratory Bronchiolitis-ILD

      • DIP

      • IPF

  • UIP and fibrotic NSIP have worse prognosis with 5 year survival ~ 50%

  • Respiratory bronchiolitis

  • Pleuroparencymal fibroelastosis

  • Diffuse alveolar damage

UIP

  • If idiopathic then called IPF

  • If secondary cause then UIP secondary to “X”

  • All features but not honeycombing - “Possible” UIP

  • Imaging features

    • Patchy fibrosis

    • Honeycombing

    • Paraseptal/Subpleural + Basal distribution

  • Findings inconsistent with diagnosis of UIP

    • Multifocal areas of ground glass or mosaic attenuation

    • Consolidation

    • Cysts

  • Complications

    • Rapid progression of IPF

      • Development of dyspnea over 1 month + new diffuse opacities on imaging

    • Lung Cancer

  • Associations

    • Rheumatoid Arthritis

    • Hypersensitivity pneumonitis

NSIP

  • Basal predominant

  • Peribronchovascular pattern

  • Rarely has honeycombing

  • Findings overlap with many other of the IPs

  • Highly correlated with secondary caused such as

    • Drug or environmental exposure

      • Asbestos

      • Nitrofurantoin

    • Collagen vascular disorders

      • Scleroderma

      • Polymyositis/Dermatomyositis

      • Hypersenitivity pneumonities

Chronic Hyprsenitivity Pneumonitis

  • Anywhere in lung

  • Imaging Characteristics

    • Mosaic attenuation

    • Centrilobular nodules

  • May be able to have some reversal with treatment

Respiratory Bronchiolitis

  • Most common form of smoking related lung injury

  • Imaging findings

  • GGO + Centrilobular nodules

  • RB-ILD = basically RB but imaging findings are worse/more prominent

DIP

  • GGO + cysts in affected area

  • Basal and peripheral preference

AIP

  • GGO + consolidative opacities - typically patchy

  • Resembles ARDS

LIP

  • Associations

    • Sjogrens

    • RA

    • Pediatric AIDS

  • GGO + peribronchovascular cysts

Idiopathic Pleuropulomary Fibroelastosis

  • Upper lobe

  • Fibrosis with volume loss and architectural distortion

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