Approach to Interstitial Lung Diseases

7/31/2019 Approach to Interstitial Lung Diseases

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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

Approach to Interstitial Lung Diseases

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