Case 23--Continued


Section 3

Gross Appearance

This slice of lung shows extensive, peripheral honeycombing (architectural distortion) in upper and lower lobes. The cystic spaces, which vary from 2 mm to 2 cm, represent traction bronchiectasis or bronchiolectasis. The dark brown areas in the upper lung represent normal lung parenchyma. This disease has a patchy distribution even at the end-stage.

The homogeneous, pale regions represent partially fibrotic lung parenchyma, some of which might show ground-glass opacity on HRCT. Note that the arterial walls are thickened as a result of the inflammation. Pulmonary hypertension may result.

In this closer view, find 2 areas of normal lung.

Find two examples of traction bronchiectasis.

Find an area of traction bronchiolectasis.

Find 2 thick-walled arteries.

Find an example of partly fibrotic lung parenchyma.

normal1normal2bronch1bronch2bronchiolarter1arter2fibrosis


Section 4: Histologic Findings

Early lesion: Here, a respiratory bronchiole is accompanied by its artery. An adjacent alveolus shows alveolitis, which consists of a thickened, edematous wall with chronic inflammatory cells, type II cell hyperplasia, and a collection of alveolar macrophages. This lesion progresses to alveolar collapse and fibrosis. It does not resolve.

 

 

Find the respiratory bronchiole.

Find the artery.

Find the alveolus with alveolitis.

rbarteryalveolitis

Fibroblast focus: A characteristic feature of the fibrosing stage is the presence of recent bluish granulation tissue next to an area of old pink scar, indicating temporal heterogeneity of the disease. Note that the granulation tissue (fibroblast focus) has already been epithelialized and incorporated into the interstitium. A few chronic inflammatory cells are present.

 

Find the granulation tissue (fibroblast focus).

Find the area of old scar.

grantisgrantisscar

Progression: As fibrosis proceeds, alveoli collapse and cause traction on small airways to eventually form honeycombed spaces with thickened walls. Note that normal alveoli are still present.

 

Find a dilated terminal bronchiole.

Find a dilated respiratory bronchiole.

Find a dilated alveolar duct.

Find a subpleural area of alveolar collapse and fibrosis.

termbronchrespbrrespbralvductcollapse

End stage, architectural distortion: This bronchiole has adjacent honeycombed spaces, some of which are filled with edema fluid. Some of the spaces are lined by bronchiolar epithelium (bronchiolization). Some of the interstitium is pink indicating fibrosis, but other parts still show fibroblast foci. Inflammatory cells are sparse. These changes constitute architectural distortion.

 

Find the bronchiole.

Find 2 honeycombed spaces with fibrotic walls.

Find a fibroblast focus.

bronchiolefibroblasthoneycomb1honeycomb2

Differential diagnosis of architectural distortion with honeycombing and traction bronchiectasis on HRCT: Idiopathic pulmonary fibrosis, collagen vascular disease (especially scleroderma), asbestosis, drug- or radiation-related fibrosis, sarcoidosis, and chronic hypersensitivity pneumonia

Histologic differential diagnosis: Usual interstitial pneumonia or end-stage disease caused by drug reaction, asbestosis, radiation, collagen vascular diseases, aspiration, or hypersensitivity pneumonia

Diagnosis: Advanced, irreversible pulmonary fibrosis consistent with usual interstitial pneumonia

Diagnostic features of usual interstitial pneumonia on HRCT

See Case Study 27 for another example of usual interstitial pneumonia.

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Normal lung

Return

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Traction bronchiectasis

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Area of traction bronchiolectasis (honeycombing)

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Thick-walled artery

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Partly fibrotic parenchyma

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Respiratory bronchiole

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Pulmonary artery

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Alveolus with alveolitis

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Granulation tissue

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Old scar

Return

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Dilated terminal bronchiole

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Dilated respiratory bronchiole

Return

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Dilated alveolar duct

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Subpleural fibrosis and collapse

Return

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Bronchiole

Return

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Honeycombed space with fibrotic walls

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Fibroblast focus

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Answers: b) Honeycomb lung, f) traction bronchiectasis. At the periphery of the lung, dilated bronchioles constitute traction bronchiolectasis.

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Honeycombing

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Traction bronchiolectasis

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Traction bronchiectasis

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