Pracical Aproach to Interstitial Lung Diseases

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Pracical Aproach to Interstitial Lung Diseases

• By
• Nour-Eldin A. Nour-Eldin

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The Lung Interstitium
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 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.
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Patterns of Interstitial Lung Disease

• 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

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Patterns of Interstitial Lung Disease
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Linear Pattern
A linear pattern is seen when there is thickening
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
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 A lines
Kerley B 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 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)

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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 of multiple 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 predominant
  distribution, 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

• SHRIMP
• Sarcoidosis
• Histiocytosis (Langerhan cell histiocytosis)
• Hypersensitivity pneumonitis
• Rheumatoid nodules
• Infection (mycobacterial, fungal, viral)
• Metastases
• Microlithiasis, alveolar
• Pneumoconioses (silicosis, coal worker's,
  berylliosis)

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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.

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How To Approach a Practical Diagnosis?
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Rule no. 1

• An acute appearance suggests pulmonary edema or
  pneumonia

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Disseminated histoplasmosis and reticulonodular
ILD. A PA chest radiograph, close-up of right
upper lung, shows reticulonodular ILD. B CT
scan shows multiple circumscribed round pulmonary
nodules, 2 to 3 mm in diameter.
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Rule no. 2
Reticulonodular lower lung predominant
distribution with decreased lung volumes
suggests (APC) 1. Asbestosis 2. Aspiration
(chronic) 3. Pulmonary fibrosis
(idiopathic) 4.Collagen vascular disease
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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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Rule no. 3

• A middle or upper lung predominant distribution
  suggests (Mycobacterium Settle Superiorly in
  Lung)
• Mycobacterial or fungal disease
• Silicosis
• Sarcoidosis
• Langerhans Cell Histiocytosis

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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 the lungs and fine bilateral
reticular ILD. B CT scan shows multiple cysts
(solid arrow) and nodules (dashed arrow).
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Rule no. 4
Associated lymphadenopathy suggests
1.Sarcoidosis 2.neoplasm (lymphangitic
carcinomatosis, lymphoma, metastases) 3.
infection (viral, mycobacterial, or fungal) 4.
silicosis
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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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Rule no. 5
Associated pleural thickening and/or
calcification suggest asbestosis.
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Rule no. 6
Associated pleural effusion suggests
1.pulmonary edema 2.lymphangitic
carcinomatosis 3.lymphoma 4.collagen vascular
disease
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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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Rule no. 7
Associated pneumothorax suggests
lymphangioleiomyomatosis or LCH.
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Lymphangioleiomyomatosis (LAM). A PA chest
radiograph shows a right basilar pneumothorax and
two right pleural drainage catheters. The lung
volumes are increased, 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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Thank You