approach to interstitial lung diseases
TRANSCRIPT
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By:Nour-Eldin A. Nour-Eldin
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The interstitium of the lung is not normally visible radiographic-ally; 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 threesubdivisions:
(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.
The Lung Interstitium
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Interstitial lung disease may result in
four patterns of abnormal opacity on
chest radiographs and CT scans: linear,
reticular, nodular, and reticulonodular These patterns are more accurately and
specifically defined on CT
Patterns of Interstitial Lung
Disease
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Patterns of Interstitial Lung
Disease
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Linear Pattern
A linear pattern is seen when there isthickening of the interlobular septa,
producing Kerley lines.
Kerley B lines
Kerley A lines
The interlobular septa contain
pulmonary veins and lymphatics.
The most common cause of interlobularseptal 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
Kerley A lines
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DD of Kerly Lines:
Pulmonary edema is the most common cause
Mitral stenosis
Lymphangitic carcinomatosis
Malignant lymphoma
Congenital lymphangiectasia
Idiopathic pulmonary fibrosis
Pneumoconiosis
Sarcoidosis
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b. Reticular Pattern
A reticular pattern results from the summationor 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)
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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.
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c. Nodular pattern
A nodular pattern consists ofmultiple round opacities,
generally ranging in diameter from 1 mm to 1 cm
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
A nodular pattern, especially with predominantdistribution, suggests a specific differential diagnosis
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Disseminated histoplasmosis and nodular ILD.
CT scan shows multiple bilateral round circumscribed
pulmonary nodules.
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Hematogenous metastases and nodular ILD. This 45-year-
old woman presented with metastatic gastric carcinoma.
The PA chest radiograph shows a diffuse pattern of
nodules, 6 to 10 mm in diameter.
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Differential diagnosis of a nodular
pattern of interstitial lung disease
SHRIMPSarcoidosis
Histiocytosis (Langerhan cell
histiocytosis)Hypersensitivity pneumonitis
Rheumatoid nodules
Infection (mycobacterial, fungal, viral)
Metastases
Microlithiasis, alveolar
Pneumoconioses (silicosis, coalworker's, berylliosis)
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d. Reticulonodular pattern
resultsA reticulonodular pattern results from acombination of reticular and nodular opacities.
This pattern is often difficult to distinguish from a
purely reticular or nodular pattern, and in such acase a differential diagnosis should be developedbased on the predominant pattern.
If there is no predominant pattern, causes of bothnodular and reticular patterns should beconsidered.
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How To Approach
a PracticalDiagnosis?
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An acute appearance suggests pulmonary
edema or pneumonia
Rule no. 1
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Disseminated histoplasmosis and reticulonodular ILD.
A: PA chest radiograph, close-up of right upper lung, shows reticulonodularILD.
B: CT scan shows multiple circumscribed round pulmonary nodules, 2 to 3
mm in diameter.
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Reticulonodularlower lung predominant
distribution with decreased lung volumes
suggests: (APC)1.Asbestosis
2.Aspiration (chronic)
3. Pulmonary fibrosis (idiopathic)
4.Collagen vascular disease
Rule no. 2
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Asbestos-related
pleural disease and
asbestosis
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Pulmonary fibrosis and rheumatoid arthritis.
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Systemic sclerosis.A: PA chest radiograph shows a bibasilar and subpleural distribution of fine
reticular ILD. The presence of a dilated esophagus (arrows) provides a clue
to the correct diagnosis.
B: CT scan shows peripheral ILD and a dilated esophagus (arrow).
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A middle or upper lung predominant distribution
suggests: (Mycobacterium Settle Superiorly in
Lung)
1. Mycobacterial or fungal disease
2. Silicosis3. Sarcoidosis
4. Langerhans Cell Histiocytosis
Rule no. 3
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Complicated silicosis. PA chest radiograph shows multiple
nodules involving the upper and middle lungs, with coalescence
of nodules in the left upper lobe resulting in early progressive
massive fibrosis
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Sarcoidosis. CT scan shows nodular thickening of the bronchovascular
bundles (solid arrow) and subpleural nodules (dashed arrow), illustrating the
typical perilymphatic distribution of sarcoidosis.
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Langerhan cell histiocytosis.
This 50-year-old man had a
30 pack-year history of
cigarette smoking.
A: PA chest radiograph
shows hyperinflation of thelungs and fine bilateral
reticular ILD.
B: CT scan shows multiplecysts (solid arrow) and
nodules (dashed arrow).
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Associated lymphadenopathy suggests :
1.Sarcoidosis
2.neoplasm (lymphangitic carcinomatosis,lymphoma, metastases)
3. infection (viral, mycobacterial, or fungal)
4. silicosis
Rule no. 4
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Simple silicosis.
A: CT scan with lung windowing shows numerous
circumscribed pulmonary nodules, 2 to 3 mm in diameter
(arrows).
B: CT scan with mediastinal windowing shows densely
calcified hilar (solid arrows) and subcarinal (dashed arrow)
nodes.
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Associated pleural thickening and/orcalcification suggest asbestosis.
Rule no. 5
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Associated pleural effusion suggests :1.pulmonary edema
2.lymphangitic carcinomatosis
3.lymphoma
4.collagen vascular disease
Rule no. 6
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Cardiogenic pulmonary edema.
PA chest radiograph shows enlargement of the cardiac
silhouette, bilateral ILD, enlargement of the azygos vein
(solid arrow), and peribronchial cuffing (dashed arrow).
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Lymphangitic carcinomatosis. This 53-year-old man
presented with chronic obstructive pulmonary disease and
large-cell bronchogenic carcinoma of the right lung.
CT scan shows unilateral nodular thickening (arrows) and a
malignant right pleural effusion.
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Associated pneumothorax suggestslymphangioleiomyomatosis or LCH.
Rule no. 7
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Lymphangioleiomyomatosis
(LAM).
A: PA chest radiograph shows a
right basilar pneumothorax and
two right pleural drainage
catheters. The lung volumes areincreased, which is
characteristic of LAM, and there
is diffuse reticular ILD.
B: CT scan shows bilateral thin-walled cysts and a loculated
right pneumothorax (P).
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Tell me the rules
again?
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1. Acute
P.Edema
Pneumonia
2. Pleural effusion
1.pulmonary edema
2.lymphangitic carcinomatosis
3.lymphoma4.collagen vascular disease
3.Pneumothorax
lymphangioleiomyom
atosisLCH
4.Predominantly Below withreduced volume
1.Asbestosis
2.Aspiration (chronic)
3. Pulmonary fibrosis (idiopathic)4.Collagen vascular disease
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5. A middle or upper lung predominant
1. Mycobacterial or fungal disease
2. Silicosis
3. Sarcoidosis4. Langerhans Cell Histiocytosis
6. Associated lymphadenopathy
1.Sarcoidosis
2.neoplasm (lymphangitic
carcinomatosis, lymphoma,
metastases)3. infection (viral, mycobacterial, or
fungal)
4. silicosis
7. Pleural Thickening
and or Calcification
Asbestosis
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Thank You