interstitial lung disease vs. alveolar lung disease

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Interstitial lung disease vs. alveolar lung
disease

• A practical approach for diagnosis

Prepared by Dr. Kosar K. ahmed
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Introduction
Lung disease can be arbitrarily divided into
Alveolar lung disease
Interstitial lung disease
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Introduction

• Opacities that are fluffy , cloud like or hazy
• Tend to be confluent
• Margins are fuzzy and indistinct
• / - air bronchograms
• Silhouette sign

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Introduction

• Discrete reticular , nodular or reticulonodular
  patterns
• Packets of disease separated by normally
  appearing lung
• Margins are sharp and discrete
• May be focal or diffuse
• No air-bronchograms

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Interstitial lung disease

• Pulmonary interstitium is the network that
  supports the lung , composed of
• Alveolar walls
• Interlobular septa
• Peribronchiolovascular interstitium

• In ILD pulmonary interstitium is thickened either
  by
• Fluid
• Cells
• Fibrosis

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Interstitial lung disease ( ILD )
This is a group of diseases that affect the
pulmonary interstitium and they show a various
patterns on HRCT

• Causes
• Idiopathic interstitial pneumonias
• Sarcoidosis
• Langerhans histeocytosis
• Lymphangiomyomatosis
• Connective tissue diseases
• Systemic vasculitides
• Drug-induced lung disease
• Occupational lung disease

• simply they can be
• Idiopathic
• Secondary

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Approach to ILD
As we can see they can be caused by a lot of
disease entities and so many changes occur
giving rise to different patterns

• The approach should combine
• clinical data ( history , physical examination ,
  lab. Investigation )
• radiologic findings
• histopathologic findings .

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Suggested form of history taking

• Onset of the disease
• Acute ( e.g. pulm. Edema , hypersensitivity
  pneumonitis )
• Chronic
• Associated illnesses
• Connective tissue diseases ( RA, SjS ,
  scleroderma , Dermatomyocitis/ poly myositis ,
  SLE , ankylosing spondylitis )
• Vasculitides ( wegners granulomatosis ,
  churg-strauss )
• Any known malignancies
• Convulsions
• Drug consumption
• Occupational history
• Smoking

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Suggested form of history taking continued

• Drugs known to cause ILD
• Chemotherapy
• NSIADs ( naproxen , indomethacin )
• Antibiotics ( ampicillin , tetracycline )
• Cardiology ( amiodarone ,
  propranolol , captopril , simvastatin ,
  sotalol anticoagulants )
• Anticonvulsants ( carbamazepine , phenytoin
  haloperidol )

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Radiologic findings encountered in ILD

• Reticular shadowing
• Nodular shadowing
• Reticulonodular shadowing
• Ground glass opacification
• Kerley lines
• Traction bronchiactasis
• Bronchial wall thickening
• Honey combing
• Cystic changes

• In practice any combination of these findings
  could be seen
• The rule is to see which pattern is the dominant
  one

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Reticular shadowing
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Nodular shadowing
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Ground glass opacification
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Kerley lines
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Traction bronchiectasis
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Bronchial wall thickening
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Honey combing
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Cystic changes
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Cyst vs. Cavity
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Approach to image interpretation

• Patterns of opacification
• Pattern of distribution
• Additional features ( LAP , Pl. thickening , Pl.
  effusion , pneumothorax , cavitation
• Cystic changes

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Idiopathic interstitial pneumonias
This is a group of diseases that are of unknown
etiology include
Usual interstitial pneumonia
NSIP
DIP
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Idiopathic interstitial pneumonias

• Patches of consolidation that tend to change
  location
• Dx. Is by histopathology

Creptogenic organizing pneumonia
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Idiopathic interstitial pneumonias

• Acute interstitial pneumonia
• Areas of consolidation , GGO traction
  bronchiectasis
• Is a grave disease and is regarded as idiopathic
  form of ARDS

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Idiopathic interstitial pneumonias
RB-ILD
Strong association with smoking
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Idiopathic interstitial pneumonias

• Associated with autoimmune diseases (e.g. SjS)
• Areas of GGO
• Centrilobular nodules
• Thickened septae
• Thin walled discrete cysts

Lymphoid interstitial pneumonia
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ILD secondary to other diseasesSarcoidosis
Sarcoidosis is a multisystem granulomatous
disorder of unknown etiology , characterized by
presence of non caseating granulomas Affecting
upper and mid zones

• CXR staging
• Stage 1 LAP
• Stage 2 LAP parenchymal opacity
• Stage 3 parenchyma opacity alone

• Other organs affected
• Skin
• P. Lymph node
• Eyes
• Spleen
• CNS
• Parotid glands
• Bones

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Sarcoidosis
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Radiologic findings of Sarcoidosis
Hilar LAP para tracheal
LAP egg shell calcification
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CT findings of Sarcoidosis
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Diagnosis is aided by
Clinical manifestations Associative features (
characteristic LAP on CXR , egg-shell
calcification If non present then
histopathology
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Hyper sensitivity pneumonitis
These are a group of disorders caused by exposure
to organic dust ( mouldy hay , tatami mats ,
paint sprays , bird feathers and others )
Characteristically symptoms develop after
approximately 6 hours of exposure ( fever , chill
, dyspnea and cough , wheeze is not prominent )
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Radiologic findings

• Ground glass opacifiction
• Centrilobular poorly defined nodules
• Reticulonodular pattern
• Upper lobe fibrosis

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Langerhans cell histiocystosis
lymphangiomyomatosis
Both cause cystic pattern on HRCT
Vs.
How to differentiate ?
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• LCH
• Occurs almost exclusively in smokers
• Associated with repeated pneumothoraces

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• LIP
• Occurs almost exclusively in women in child
  bearing age
• Associated with autoimmune diseases e.g. SJS

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Connective tissue diseases , systemic
vasculitides occupational lung disease
These cause variable disease patterns that may be
shared by two or more diseases

• Multiple pulmonary nodules
• Cavitary pulmonary nodule
• Miliary pulmonary nodules
• Lower lobe interstitial lung disease
• Upper lobe interstitial lung disease

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Multiple pulmonary nodules
DDx. Metastasis Granulomatous disease ( TB
fungi ) Septic emboli Wegners granulomatosis
Rheumatoid disease
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• Wegners granulomatosis
• Nodules tend to cavitate
• Associated with multiple sinus infections /-
  soft tissue mass in the upper air ways

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• Rheumatoid disease
• Rheumatoid nodule in the chest occurs in those
  who have skin nodules

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Lower lobe interstitial lung disease

• DDx.
• UIP
• Collagen vascular disease( RA , SLE scleroderma
  )
• Asbestos related
• Drug toxicity

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Collagen vascular disease
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Upper lobe interstitial lung disease

• DDx.
• Post primary TB
• Sarcoidosis
• Cystic fibrosis
• Silicosis
• LCH

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Drug induced ILD

• Non specific
• Almost any pattern

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Alveolar lung disease

• This is a non specific finding due to replacement
  of air in the alveoli by
• Fluid
• Transudate
• Exudate
• Blood
• Protein
• Cells
• Gastric juice

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Radiologic signs of air-space shadowing

• Nodular pattern
• Ground glass opacification
• Consolidation

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Pulmonary edema

• This is defined as excess extra vascular lung
  water
• It can be caused by
• Increased hydrostatic pressure ( cardiogenic )
• Increased vascular permeability ( non cardiogenic
  )

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Non cadriogenic causes
Blood Fluid over load IV contrast Drugs
(narcotics , NSAID ) Brain CVA Raised ICP chest
High altitude Drowning Re-expansion of a
collapsed lung
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CXR findings
Kerley B lines Kerley A lines Peribronchial
cuffing
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Alveolar edema

• The distribution of changes is variable and
  frequently random
• in general, there is sparing of the apices and
  extreme lung bases. Typically, there is bilateral
  opacification
• On occasion, the central lungs are more
  affected, producing the characteristic
  butterfly or bat's wing

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Is it possible to differentiate cardiogenic from
non cardiogenic radiologicaly ?

• Suggestive features
• Cardiomegaly
• Upper lobe Vs. lower lobe
• Peripheral Vs. central
• Width of the vascular pedicle

Differentiation of the cause of pulmonary edema
based on radiological features alone is un
reliable
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Pulmonary hemorrhage
Diffuse This is caused by many diseases that can
non be differentiated radiologicaly

• Localized
• Carcinomas
• Bronchiectasis
• Pneumonias

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Radiologic findings

• Ground glass opacification
• Consolidation

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Thank you