Interstial lung disease
Chronic diffuse interstitial restrictive
lung disease
• Heterogenous group of diseases characterized by
Inflammation & fibrosis of most peripheral interstitial
connective tissue in the alveolar walls
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It concerns
alveolar epithelium,
pulmonary capillary endothelium,
basement membrane,
perivascular and perilymphatic tissues.
The Lung Interstitium
The interstitium of the lung is not normally visible radiographically; it becomes visible only when disease (e.g., edema,
fibrosis, tumor) increases its volume and attenuation.
The interstitial space is defined as continuum of loose
connective tissue throughout the lung composed of three
subdivisions:
(i) the bronchovascular (axial), surrounding the bronchi,
arteries, and veins from the lung root to the level of the
respiratory bronchiole
(ii) the parenchymal (acinar), situated between the alveolar
and capillary basement membranes
(iii) the subpleural, situated beneath the pleura, as well as in
the interlobular septae.
Patterns of Interstitial Lung Disease
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Interstitial lung disease may result in four
patterns of abnormal opacity on chest
radiographs and CT scans:
linear,
reticular,
nodular,
Reticulonodular
These patterns are more accurately and
specifically defined on CT
Patterns of Interstitial Lung Disease
Linear Pattern
A linear pattern is seen when there is
thickening of the interlobular septa,
producing Kerley lines.
Kerley A lines
Kerley B lines
Kerley A lines
The interlobular septa contain
pulmonary veins and lymphatics.
The most common cause of interlobular
septal thickening, producing Kerley A
and B lines, is pulmonary edema, as a
result of pulmonary venous
hypertension and distension of the
lymphatics.
Kerley B lines
DD of Kerly Lines:
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Pulmonary edema is the most common cause
Mitral stenosis
Lymphangitic carcinomatosis
Malignant lymphoma
Congenital lymphangiectasia
Idiopathic pulmonary fibrosis
Pneumoconiosis
Sarcoidosis
b. Reticular Pattern
A reticular pattern results from the summation
or superimposition of irregular linear
opacities.
The term reticular is defined as meshed, or in
the form of a network. Reticular opacities can be
described as fine, medium, or coarse, as the
width of the opacities increases.
A classic reticular pattern is seen with pulmonary fibrosis,
in which multiple curvilinear opacities form small
cystic spaces along the pleural margins and lung
bases (honeycomb lung)
This 50-year-old man presented with end-stage lung fibrosis
PA chest radiograph shows medium to coarse reticular
B: CT scan shows multiple small cysts (honeycombing) involving
predominantly the subpleural peripheral regions of lung. Traction
bronchiectasis, another sign of end-stage lung fibrosis.
c. Nodular pattern
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A nodular pattern consists of multiple round opacities,
generally ranging in diameter from 1 mm to 1 cm
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Nodular opacities may be described as miliary (1 to 2 mm,
the size of millet seeds), small, medium, or large, as the
diameter of the opacities increases
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A nodular pattern, especially with predominant
distribution, suggests a specific differential diagnosis
Disseminated histoplasmosis and nodular ILD.
CT scan shows multiple bilateral round circumscribed
pulmonary nodules.
Hematogenous metastases and nodular ILD. This 45-yearold woman presented with metastatic gastric carcinoma.
The PA chest radiograph shows a diffuse pattern of
nodules, 6 to 10 mm in diameter.
Differential diagnosis of a nodular pattern
of interstitial lung disease
SHRIMP
Sarcoidosis
Histiocytosis (Langerhan cell
histiocytosis)
Hypersensitivity pneumonitis
Rheumatoid nodules
Infection (mycobacterial, fungal, viral)
Metastases
Microlithiasis, alveolar
Pneumoconioses (silicosis, coal
worker's, berylliosis)
d. Reticulonodular pattern results
A reticulonodular pattern results from a
combination of reticular and nodular opacities.
This pattern is often difficult to distinguish from a
purely reticular or nodular pattern, and in such a
case a differential diagnosis should be developed
based on the predominant pattern.
If there is no predominant pattern, causes of both
nodular and reticular patterns should be
considered.
Diffuse parenchymal lung disease
Known cause
Drugs
Collagen vascular
Idiopathic
Interstitial
Pneumonia
Idiopathic Pulmonary Fibrosis
CFA/IPF
UIP
Granulomatous
Sarcoidosis
Others
AIP
Acute
Interstitial Pneumonia
DIP
Desquamative
Interstitial Pneumonia
RBILD
Pespiratory Bronchiolitis
Interstitial Lung Disease
COP
Cryptogenic
Organising Pneumonia
LIP
Lymphocytic
Interstitial Pneumonia
(NSIP)
Nonspecific
Interstitial Pneumonia
Other specific
LAM
Histiocytosis
Classification of interstitial / diffuse parenchymal lung
disease
Idiopathic pulmonary fibrosis/usual interstitial pneumonia
(IPF/UIP/CFA)
• Non-specific interstitial pneumonia (NSIP)
• Desquamative interstitial pneumonia (DIP)
• Respiratory bronchiolitis/interstitial lung disease (RB/ILD)
• Acute interstitial pneumonia (AIP)
• Lymphoid interstitial pneumonia (LIP)
• Cryptogenic organising pneumonia (COP)
Environmental and occupational diseases
• Pneumoconiosis eg asbestosis, silicosis
• Extrinsic allergic alveolitis (EAA), for example, bird fancier’s lung
Classification of interstitial / diffuse parenchymal lung
disease
Multisystem diseases
• Connective tissue diseases, for example, systemic sclerosis,
• Sarcoidosis
• Wegener’s granulomatosis
• Tuberose sclerosis ,lymphangioleiomyomatosis (LAM)
• Drug reactions, for example, amiodarone, methotrexate, bleomycin
Rare lung diseases
• Pulmonary alveolar proteinosis
• Pulmonary histiocytosis
• Pulmonary eosinophilia
• Idiopathic pulmonary haemosiderosis
Chronic diffuse interstitial lung diseases
• RESTRICTIVE (INFILTRATIVE)
• Dyspnea, tachypnea, end inspiratory crackles without airway
obstruction.
• ↓ CO diffusing capacity, ↓lung volume. ↓compliance.
• Honey-comb lung
• Secondary pulmonary hypertention
• Corpulmonale
Chronic diffuse interstitial lung diseases
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Restrictive (infiltrative)
Reduced compliance, reduced gas exchange)
Are also diffuse
Heterogeneous main categories of CILD
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FIBROSING
GRANULOMATOUS
EOSINOPHILIC
SMOKING RELATED
PAP (Pulmonary Alveolar Proteinosis)
1.FIBROSING
• Usual interstitial pneumonia-Idiopathic pulmonary fibrosis
(UIP-IPF-CFA).
• Nonspecific interstitial pneumonia / fibrosis
• Cryptogenic organizing pneumonia
• Connective tissue (Collagen vascular) diseases
• Pneumoconioses
• Drug reactions
• Radiation changes
IPF (UIP/CFA)
• Cobblestone pleural surface by retraction
scar along interlobular septa.
• Lower lobe subpleural & interlobular septal
fibrosis.
• Fibroblastic foci - honeycomb fibrosis
IPF (UIP/CFA)
NON-SPECIFIC INTERSTITIAL
PNEUMONIA
– Fibroblastic foci &
honey combing
absent.
– Cellular infiltrate
(lymphs & plasma
cells)
Cryptogenic organizing
pneumonia (cop)
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Idiopathic
“Bronchiolitis obliterans organizing peumonia” BOOP
Some alveolar spaces are filled by ball of fibroblast
(masson bodies) but alveolar walls are normal.
All lesion are of same age.
No intertstitial fibrosis or honeycomb lung.
Connective tissue “Collagen”
vascular diseases
• Rheumatoid Arthritis
• SLE (“Lupus”)
• Progressive Systemic Sclerosis
(Scleroderma)
Pneumoconioses
• Non-neoplastic lung reaction to inhalation of mineral dust
or chemicals or organic materials
• “Occupational”-“Coal miners lung”
• 1-5µm diameter particles can reach airsacs & settle in their
linning.
– Coal (anthracosis)
– Silica
– Asbestos
– Be, FeO, BaSo4, Tin oxide
– HAY, FLAX, Benzene, Insecticides, etc.
Pneumoconioses
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Coal workers peumoconiosis CWP
Asymtomatic anthracosis
Simple CWP
Complicated CWP or PMF
Silicosis
Hard collagenous scars in upper lobes of
lung
• Eggshell calcification of lymphnodes
Pneumoconioses
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Asbestos-related disease
Localized fibrous plaque
Pleural effusions
Interstitial fibrosis
Carcinoma lung
Mesothelioma
Laryngeal or colonic carcinomas
2.Granulomatous
• Sarcoidosis,
• Hypersensitivity peumonitis
Sarcoidosis
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By excluding other causes of non-caseating granulomas
Bilateral hilar LA or lung involvement in 90%.
Disordered immune regulation.
Intra-alveolar & interstitial CD4/CD8 ratio 5:1 →15:1
↑Th1 cytokine IL-2 ,IFNϫ, TNF,IL-8
-ve tuberculin test
Polyclonal hyper-ϫglobulinemia
Stellete inclusions Asteroid bodies & ,laminated calcium
concretion Schumann bodies in giant cells in 60%
NON-Caseating Granulomas are the RULE
“Asteroid” bodies within these granulomas
are virtually diagnostic
3-Hypersensitivity peumonitis
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(dusts, bacteria, fungi,)
farmer’s lung →thermophilic actinomycosis,
pigeon breeder’s lung →proteins derived from birds
Histology
Interstitial peumonitis
Non-caseating granulomas in 2/3rd patients
Interstitial fibrosis, honeycombing & obliterative
bronchiolitis
• Intra-alveolar infiltrate
4-Smoking related
Desquamative Interstitial
Pneumonia ( DIP )
– M>>F
– Cigarettes
– 100% Survival
Alveolar
Macrophages
4-Smoking related
• Respiratory Bronchiolitis-Associated Interstitial
Lung Disease
• Pigmented intraluminal macrophages within Resp.
bronchioles. Macrophages are similar to those in DIP.
5-PAP (Pulmonary Alveolar Proteinosis)
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Accumulation of intra-alveolar & intra-bronchial acellular
surfactant.
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Acquired (anti-GM-CSF Ab),
Congenital immediate onset neonatal respiratory distress ABCA3, SPB,SP-C
Secondary hemopoetic & inhalation syndrome
END