Chapter 17: Diffuse Lung Disease

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Differential for groundglass opacities:
-Allergic hypersensitivity
-All acute interstitial disease (AIP, DIP, active UIP, viral)
-PCP
-BOOP/COP
-Eosinophilic pneumonia
-Pulmonary edema

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Differential for lower lobe predominant disease:
"BADAS"
-Bronchiectasis
-Aspiration
-Drug reaction, DIP
-Asbestosis
-Scleroderma (other collagen vascular diseases)

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Differential for calcified pleural plaques?

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-Old Tuberculosis
-Old Hematoma
-Asbestos-related pleural plaques
-Talc pleurodesis

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Differential for lots of small cysts?

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Differential for lots of small cysts:
-EG
-LAM or tuberous sclerosis
-Cystic PCP
-Honeycombing in any end stage interstitial disease
-Emphysema (no cyst wall)

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Differential for crazy paving:

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Differential for crazy paving:
-Alveolar proteinosis
-ARDS
-PCP
-Lipoid pneumonia
-Hemorrhage
-BAC
-Pulmonary edema

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Describe the axial and peripheral interstitium:

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-The central interstitial compartment extending from the mediastinum peripherally and enveloping the bronchovascular bundles is termed the axial or bronchovascular interstitium.
-The axial interstitium is contiguous with the interstitium surrounding the small centrilobular arteriole and bronchiole within the secondary pulmonary lobule, where it is called the centrilobular interstitium.
-The most peripheral component of the interstitium is the subpleural or peripheral interstitium, which lies between the visceral pleura and the lung surface.
-Invaginations of the subpleural interstitium into the lung parenchyma form the borders of the secondary pulmonary lobules and represent the interlobular septa.
-Extending between the centrilobular interstitium within the lobular core and the interlobular septal/subpleural interstitium in the lobular periphery is a fine network of connective tissue fibers that support the alveolar spaces called the intralobular, parenchymal, or alveolar interstitium.

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Describe a secondary pulmonary lobule:

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-The secondary pulmonary lobule is defined as that subsegment of lung supplied by three to five terminal bronchioles and separated from adjacent secondary lobules by intervening connective tissue (interlobular septa)
-The centrilobular artery and preterminal bronchiole are located in the center of the secondary lobule.
-Pulmonary veins and lymphatics run at the margins of lobules within the interlobular septa, with lymphatics and connective tissue found within the contiguous subpleural interstitium.
-The secondary pulmonary lobule is typically polyhedral in shape, with each side ranging from 1.0 to 2.5 cm in length.

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What does interlobular septal thickening look like on plain films?

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Interlobular lines on HRCT are the equivalent of Kerley B lines seen in the inferolateral portions of the lungs on frontal radiographs.

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What does interlobular septal thickening look like on CT? What things can cause it?

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-Septal thickening is most often seen as thin, short, 1- to 2-cm lines oriented perpendicular to and intersecting the costal pleura.
-Although septa can be seen in normal individuals, these lines are thicker (>1 mm) and more numerous in patients with diseases primarily affecting the interlobular interstitium, such as interstitial pulmonary edema, idiopathic pulmonary fibrosis (and other forms of usual interstitial pneumonia [UIP]), sarcoidosis, and lymphangitic carcinomatosis

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What does intralobular septal thickening look like on CT? What sorts of things cause it?

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-In some patients, a lattice of fine lines is seen within the central portion of the pulmonary lobule radiating out toward the thickened lobular borders to produce a “spoke-and-wheel” or “spiderweb” appearance.
-These lines are not normally visible on HRCT and represent thickening of the intralobular or parenchymal interstitium.
-Intralobular lines usually represent fibrosis and are most commonly seen in idiopathic pulmonary fibrosis (IPF) and other forms of usual interstitial pneumonia (UIP).
-However, intralobular lines can also be seen in other infiltrative diseases such as pulmonary alveolar proteinosis (PAP), hypersensitivity pneumonitis (chronic), and asbestosis

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Why would the interlobar fissues be thickened in diffuse interstitial lung disease? What are the two types of fissural thickening? What sorts of diseases cause fissural thickening?

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-The apparent thickening of interlobar fissures in patients with interstitial lung disease is usually a direct extension of the thickening of interlobular septa to involve the subpleural interstitium of the lung.
-While such a process normally involves all pleural surfaces equally, the “thickening” is usually best appreciated on the fissures, where two layers of visceral pleura—and therefore two layers of subpleural interstitium—are seen outlined on either side by aerated lung.

-The fissural thickening can be smooth or nodular.
-Smooth fissural thickening is virtually indistinguishable from a small amount of pleural fluid within the fissure and is most commonly seen with pulmonary edema.
-Nodular fissural thickening is commonly seen in sarcoidosis and lymphangitic carcinomatosis, where the nodules lie within the subpleural lymphatics.

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What does peribronchovascular thickening look like? What causes it?

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-Thickened bronchovascular structures of the lung result from thickening of the peribronchovascular interstitium.
-This produces apparent enlargement of perihilar vascular structures and thickening of bronchial walls, which is the HRCT equivalent of peribronchial cuffing and tram tracking seen radiographically.
-While pulmonary edema causes smooth thickening of the peribronchovascular interstitium, nodular or irregular thickening can be seen in sarcoidosis or UIP.
-Lymphangitic carcinomatosis can result in either smooth or irregular peribronchovascular thickening, although the former is more common

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What does thickening of the centrilobular artery look like? What sorts of things cause it? What does thickening of the terminal bronchiole look like? What sorts of things cause it?

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-Thickening of the axial interstitium within the lobular core produces an abnormal prominence of the “dotlike” or branching centrilobular arteriole.
-Diseases that commonly produce this appearance include pulmonary edema, lymphangitic carcinomatosis, and UIP.
-The centrilobular bronchiole is not normally seen on HRCT but may be rendered visible as a result of luminal dilatation or thickening of the centrilobular interstitium.
-Small airways disease can produce centrilobular bronchiolar abnormalities, which are seen on HRCT as fluid-filled dilated branching Y-shaped structures that produce a “tree-in-bud” appearance.
-Ill-defined centrilobular nodules represent disease of the bronchiole and adjacent parenchyma and can be seen in subacute hypersensitivity pneumonitis, cryptogenic organizing pneumonia (COP), and respiratory bronchiolitis–associated interstitial lung disease (RB-ILD).

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What are subpleural lines? What should you try to distinguish them from? What sorts of diseases cause them?

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-These 5- to 10-cm-long curvilinear opacities are found within 1 cm of the pleura and parallel the chest wall.
-They are most frequent in the posterior portions of the lower lobes and remain unchanged on prone scans.
-This finding, which probably represents an early phase of lung fibrosis, should be distinguished from a similar line that is seen as a result of atelectasis in the dependent portion of the lungs in normal individuals.
-Subpleural lines are most often seen in patients with asbestosis and, less commonly, IPF.

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What are parenchymal bands? What sorts of diseases cause them?

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-Parenchymal bands are nontapering linear opacities, 2 to 5 cm in length, that extend from the lung to contact the pleural surface.
-These fibrotic bands can be distinguished from vessels and thickened septa by their length, thickness, course, absence of branching, and their association with regional parenchymal distortion.
-Parenchymal bands are usually seen in asbestosis, IPF, and sarcoidosis.

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What is honeycombing? What sorts of diseases cause it?

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-Honeycombing, seen as small (6 to 10 mm) cystic spaces with thick (1 to 3 mm) walls, most often in the posterior subpleural regions of the lower lobes, represents end-stage pulmonary fibrosis of various etiologies.
-Pathologically, the cysts are lined by bronchiolar epithelium and are the result of bronchiolectasis.
-Most patients show additional signs of interstitial disease, including thickened interlobular and intralobular lines, parenchymal bands, irregularity of lung interfaces, and areas of ground-glass opacification.
-Honeycombing is frequently seen in IPF (and other forms of UIP), chronic hypersensitivity pneumonitis, asbestosis, and occasionally sarcoidosis.

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How can you tell the difference between thin walled cysts and honeycombing? What sorts of diseases cause thin walled cysts?

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-Thin-walled cysts are a common manifestation of late stages of Langerhans cell histiocytosis of lung (LCH) and lymphangioleiomyomatosis (LAM).
-These cysts are slightly larger in diameter (10 mm) than honeycomb cysts, are more uniform in size, and have thinner walls.
-Honeycomb cysts usually have shared walls, while the cysts of LCH and LAM do not.
-The cysts of LCH and LAM are usually evenly distributed from central to peripheral portions of the upper lobes, with or without lower lobe involvement, while honeycombing tends to occur in the subpleural regions of the lower lobes.
-While normal lung may be found in the intervening spaces between the cysts of LCH and LAM, honeycombing uniformly destroys lung and produces distortion of lung interfaces and traction bronchiectasis, features not found in eosinophilic granulomatosis (EG) and LAM.
-Thin walled cysts can also be seen in lung disease related to tuberous sclerosis and neurofibromatosis.

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Define micronodule:
What do they represent on path?

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These 1- to 3-mm, sharply marginated, round opacities seen on HRCT represent conglomerates of granulomas or tumor cells within the interstitium.

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What entities cause a random distribution of micronodules?
What entities cause a perilymphatic distribution?

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Random:
-Miliary tuberculosis or histoplasmosis
-Hematogenous metastases
-Silicosis/coal worker's pneumoconiosis (CWP)
-EG

Perilymphatic:
-Sarcoidosis
-Lymphangitic carcinomatosis
-Silicosis/CWP

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Describe a perilymphatic distribution:

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Nodules predominating in the peribronchovascular, interlobular, and subpleural regions—those portions of the interstitium where the lymphatics lie—are said to have a “perilymphatic” distribution.

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What are the two types of alveolar opacities? How can you distinguish the two?

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-Ground-glass and consolidation
-Ground glass opacities often respect lobular borders, are distinguished from consolidation by their granular appearance with maintained visibility of pulmonary vessels and the absence of air bronchograms.

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What does ground glass opacity imply?

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-The presence of ground-glass opacities is important because it often implies an active inflammatory process or edema that is reversible and warrants aggressive treatment.
-However, ground-glass abnormality associated with a predominant pattern of honeycombing can represent microscopic pulmonary fibrosis.

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What entities can cause ground-glass opacities?

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-UIP
-Desquamative interstitial pneumonia
-Acute interstitial pneumonia (AIP)
-Hypersensitivity pneumonitis
-BOOP/COP
-RB-ILD
-Hemorrhage
-Pneumocystis jiroveci pneumonia
-Cytomegalovirus pneumonia
-Alveolar proteinosis

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What entities cause architectural distortion?

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-Processes that result in extensive parenchymal fibrosis can distort the normal architecture of the lung, creating irregularities of the lung–mediastinal, lung–pleural, and lung–vascular interfaces.
-Sarcoidosis and UIP are the diseases most commonly associated with architectural distortion.

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What entities cause traction bronchiectasis?

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-IPF/UIP
-Sarcoidosis
-Silicosis/CWP

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What interstitial lung diseases cause a conglomerate mass?

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-Sarcoidosis
-Silicosis
-CWP (esp with progressive massive fibrosis-PMF)
-Radiation fibrosis
-A similar finding is seen rarely in intravenous drug users when a granulomatous fibrosis results as a response to intravenous talc or starch mixed with narcotics.

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What interstitial lung diseases cause consolidation?

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-BOOP/COP
-Sarcoidosis
-AIP
-UIP
It can occur with any airspace filling process but occassionally occurs with these interstitial processes.

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What's your differential for interstitial lung disease with an upper lobe predominance?

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"CASSET P"
-Cystic fibrosis
-Ankylosing spondylitis
-Sarcoidosis
-Silicosis
-Eosinophilic granuloma
-Tuberculosis (postprimary)

-PCP
Also:
-Chronic fungal infection (histoplasmosis, coccidioidomycosis)
-Hypersensitivity pneumonitis (chronic)
-Radiation fibrosis from treatment of head and neck malignancy

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What your differential for interstitial lung disease with a lower lobe predominance?

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"SAD DAN"

-Scleroderma and other collagen vascular diseases (Rheumatoid, Dermatomyositis/polymyositis)
-Aspiration
-DIP

-Drug reaction
-Asbestosis
-Neurofibromatosis

Don't forget UIP!

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What's your differential for interstitial lung disease with normal or increased lung volumes?

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-Sarcoidosis
-Eosinophilic granuloma
-Lymphangioleiomyomatosis
-Tuberous sclerosis
-Interstitial disease superimposed on emphysema

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What your differential for interstitial lung disease with lots of honeycombing?

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-Idiopathic pulmonary fibrosis
-Sarcoidosis
-Eosinophilic granuloma
-Rheumatoid lung
-Scleroderma
-Pneumoconiosis
-Hypersensitivity pneumonitis
-Chronic aspiration
-Radiation fibrosis

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What's your differential for miliary nodules?

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-Tuberculosis
-Fungi (histoplasmosis, coccidioidomycosis, cryptococcosis)
-Silicosis
-Metastases (thyroid carcinoma, renal cell carcinoma, bronchogenic carcinoma, melanoma, choriocarcinoma)
-Sarcoidosis
-Eosinophilic granuloma

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What's your differential for interstitial lung disease with hilar/mediastinal lymphadenopathy?

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-Sarcoidosis
-Lymphangitic carcinomatosis
-Lymphoma
-Hematogenous metastases
-Tuberculosis
-Fungal infection
-Silicosis

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What's your differential for interstitial lung disease associated with pleural disease?

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-Asbestosis (plaques)
-Lymphangitic carcinomatosis (effusion)
-Rheumatoid lung disease (effusion/thickening)
-Lymphangioleiomyomatosis (chylous effusion)

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What's your differential for interstitial lung disease associated with skin nodules?

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Neurofibromatosis

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What's your differential for interstitial lung disease associated with skin calcifications?

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-Dermatomyositis
-Scleroderma

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What's your differential for interstitial lung disease associated with erosion of the distal clavicles?

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-Rheumatoid lung
-Scleroderma

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What's your differential for interstitial lung disease associated with erosion of the inferior rib margins? What about erosion of the superior rib margins?

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Inferior:
-Neurofibromatosis

Superior:
-Rheumatoid lung
-Scleroderma

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What's your differential for interstitial lung disease associated with kyphoscoliosis?

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Neurofibromatosis

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What's your differential for interstitial lung disease associated with lytic bone lesions?

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-Metastases
-Eosinophilic granuloma

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How does chronic pulmonary edema cause interstitial lung disease?
Which pts tend to have this?
What does it look like?
What findings is NOT associated with chronic interstitial pulmonary edema? What should you think of if you see it?

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-Chronic elevation of pulmonary venous pressure may lead to interstitial thickening is caused by distention of pulmonary lymphatics and chronic interstitial edema, which may lead to fibrosis.
-This is seen most commonly in patients with long-standing mitral stenosis or LV failure.
-Radiographically, peribronchial cuffing, tram tracking, poor definition of vascular markings, and linear or reticular opacities may be seen.
-Redistribution of blood flow to the upper lobes, a manifestation of pulmonary venous hypertension, and prominence of the fissures caused by subpleural edema and fibrosis are concomitant findings.
-Honeycombing is not a feature of chronic pulmonary venous hypertension; its presence in a patient with cardiac disease should suggest another cause of pulmonary fibrosis (e.g., amiodarone lung toxicity).

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Which pts tend to get rheumatoid lung disease?

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In contrast to the disease as a whole, which is more common in women, pulmonary involvement is more common in men.

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Describe the typical pattern of rheumatoid lung disease:

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-The most common radiographic manifestation of parenchymal lung involvement is an interstitial pneumonitis and fibrosis, which histologically is a form of UIP.
-This begins as an alveolitis (inflammation of the alveolar interstitium) that is seen radiographically as fine reticular or ground-glass opacities with a lower zone predominance.
-There is gradual progression to end-stage pulmonary fibrosis with the development of a bibasilar medium or coarse reticular or reticulonodular pattern (honeycombing)
-Less common parenchymal manifestations of rheumatoid disease are lung nodules and changes attributable to COP.
-Necrobiotic (rheumatoid) nodules in the lung can produce peripheral well-defined nodular opacities on chest radiographs
-The lung nodules commonly evolve into thick-walled cavities, which tend to wax and wane in parallel with the flares of arthritis.
-COP and bronchiolitis obliterans (constrictive bronchiolitis) are associated with rheumatoid disease.

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How do the following aspects of rheumatoid lung disease manifest on thoracic imaging?
1. Serositis
2. Interstitial pneumonitis
3. Necobiotic nodules
4. Bronchiolitis obliterans
5. Pulmonary arteritis
6. MSK manifestations

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1. Pleural effusion and thickening, pericardial effusion
2. Pulmonary fibrosis (basilar predominance)
3. Multiple peripheral cavitating nodules
4. Hyperinflation
5. Pulmonary arterial hypertension and right heart enlargement, pulmonary hemorrhage
6. Tapered erosion of the distal clavicles, rotator cuff atrophy with a high-riding humeral head, bilateral symmetric glenohumeral joint space narrowing with or without superimposed degenerative joint disease, and superior rib notching or erosion.

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What is Caplan syndrome?
How can you tell it apart from necrobiotic nodules?

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-Pulmonary nodules may develop in the lungs of coal miners and silica or asbestos workers with rheumatoid arthritis as a hypersensitivity response to inhaled dust particles.
-Caplan syndrome is usually indistinguishable radiographically from the necrobiotic nodules of simple rheumatoid disease, although the presence of the associated characteristic small nodular or irregular parenchymal opacities of simple pneumoconiosis helps make this distinction

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What are necrobiotic nodules?

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Necrobiotic (rheumatoid) nodules in the lung can produce peripheral well-defined nodular opacities on chest radiographs that are indistinguishable from the subcutaneous rheumatoid nodules seen on the extensor surfaces of the elbows and knees in these patients. The lung nodules commonly evolve into thick-walled cavities, which tend to wax and wane in parallel with the flares of arthritis.

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What is the most common thoracic manifestation of rheumatoid arthritis?

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-Pleuritis is the most common thoracic manifestation of rheumatoid disease and is found in 20% of patients.
-As with pulmonary involvement, there is a male predilection for pleural disease.
-Unilateral or bilateral pleural effusions may be seen that are exudative and have a characteristically low glucose concentration.

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Describe the pulmonary and thoracic manifestations of lupus:

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-The thoracic disease is often limited to the pleura and pericardium, although the lung, heart, diaphragm, and intercostal muscles are involved in as many as one third of patients.
-In the pleura and pericardium, a fibrinous serositis produces painful pleural and pericardial effusions that are exudative in nature.
-Pleural fibrosis, seen in a majority of patients with long-standing disease, results in diffuse pleural thickening.

-Pulmonary involvement may take the form of acute lupus pneumonitis or chronic interstitial disease.
-Acutely, these patients have pathologic changes that are indistinguishable from those seen in ARDS, with diffuse alveolar damage producing an exudative intra-alveolar edema with hyaline membrane formation.
-Radiographically, rapidly coalescent bilateral airspace opacities are seen, while the typical HRCT finding is one of ground-glass opacity.
-These findings are difficult to distinguish from those seen in diffuse alveolar hemorrhage associated with pulmonary vasculitis, severe pneumonia related to immunosuppressive therapy, or pulmonary edema secondary to renal failure.
-Radiographic evidence of IPF is distinctly uncommon in SLE
-When seen radiographically, the pattern is one of bibasilar reticular opacities that are indistinguishable from those seen in rheumatoid lung disease or scleroderma.
-Therefore, the presence of severe interstitial fibrosis in a patient with clinical features of SLE should prompt consideration of the diagnosis of an overlap syndrome (mixed connective tissue disease).
-Diaphragmatic elevation is present in as many as 20% of patients and is the result of diaphragmatic weakness from a primary myopathy
-Superior rib erosions may be seen that are indistinguishable from similar findings in rheumatoid arthritis or scleroderma.

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What should you think if you see UIP/IPF in a lupus patient?

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-Radiographic evidence of IPF is distinctly uncommon in SLE
-When seen radiographically, the pattern is one of bibasilar reticular opacities that are indistinguishable from those seen in rheumatoid lung disease or scleroderma.
-Therefore, the presence of severe interstitial fibrosis in a patient with clinical features of SLE should prompt consideration of the diagnosis of an overlap syndrome (mixed connective tissue disease).

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Which autoimmune disease is associated with an elevated hemidiaphragm?

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-Diaphragmatic elevation is present in as many as 20% of lupus patients and is the result of diaphragmatic weakness from a primary myopathy

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What percent of scleroderma patients have pulmonary involvement?
How does it present on imaging?

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-The lungs are involved pathologically in nearly 90% of patients, although only 25% of patients have respiratory symptoms or radiographic evidence of pulmonary involvement.
-Severe pulmonary involvement is reflected radiographically as a coarse reticular or reticulonodular pattern involving the subpleural regions of the lower lobes.
-The most common HRCT findings are interlobular septal thickening, ground-glass opacities, and honeycombing
-Progressive loss of lung volume is seen with advancing pulmonary fibrosis.
-The development of large (1 to 5 cm) subpleural lower lobe cysts may lead to spontaneous pneumothorax
-Pulmonary arterial hypertension with enlarged central pulmonary arteries and RV dilatation is seen and may be present in the absence of interstitial fibrosis.
-In these patients, thickening and obliteration of small muscular pulmonary arteries are responsible for the development of PAH
-Pleural effusions are significantly less common in scleroderma than in rheumatoid disease or SLE and may be a helpful distinguishing feature radiographically.
-Pleural thickening is more often attributable to extension of pulmonary interstitial fibrosis into the interstitial layer of the pleura than to pleuritis.
-Eggshell calcification of mediastinal lymph nodes has been reported, although it is more common in silicosis and sarcoidosis.
-A dilated air-filled esophagus may be identified on the upright chest radiograph and is a manifestation of esophageal dysmotility from smooth muscle atrophy
-An air–fluid level within a dilated esophagus suggests secondary distal esophageal stricture formation from chronic reflux esophagitis.
-The functional or anatomic esophageal obstruction may result in aspiration with the development of lower lobe pneumonia.
-Patients with scleroderma are at a greater risk for developing lung cancer, particularly bronchioloalveolar cell carcinoma
-Patients with CREST syndrome (subcutaneous calcification, Raynaud phenomenon, esophageal dysmotility, sclerodactyly, and telangiectasia) may have radiographically visible calcifications within the subcutaneous tissues of the chest wall.
-Superior rib notching or erosion may be seen.

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Describe pulmonary and thoracic manifestations of polymyositis and dermatomyositis:

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-A fine reticular interstitial pattern in acute disease leads to a chronic, coarse reticular or reticulonodular process that is predominantly basilar in distribution.
-Additional chest radiographic findings in polymyositis reflect the involvement of skeletal muscle.
-Small lung volumes with diaphragmatic elevation and basilar linear atelectasis are secondary to diaphragmatic and intercostal muscle involvement.
-Pharyngeal and upper esophageal muscle weakness predispose to aspiration pneumonia.
-The chest radiograph should be examined carefully for lung masses because bronchogenic carcinoma accounts for a significant percentage of the malignancies seen with a higher-than-normal frequency in patients with dermatomyositis or polymyositis

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Describe imaging manifestations of Sjorgen's syndrome:

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-The most common manifestation is interstitial fibrosis, which is indistinguishable from that seen with other collagen vascular disorders.
-Involvement of tracheobronchial mucous glands leads to thickened sputum with mucus plugging and recurrent bronchitis, bronchiectasis, atelectasis, and pneumonia.
-HRCT demonstrates both interstitial opacities and the presence of small airways involvement with bronchiolectasis and a “tree-in-bud” appearance.
-Pleuritis and pleural effusion are less common.
-Patients with Sjögren syndrome are at increased risk for developing lymphocytic interstitial pneumonitis (LIP) and non-Hodgkin pulmonary lymphoma.
-The radiographic appearance of LIP is lower lobe coarse reticular or reticulonodular opacities that are indistinguishable from interstitial fibrosis.
-HRCT shows ground-glass opacity with scattered, thin-walled cysts.
-The development of lymphoma in these patients should be suspected when nodular or alveolar opacities develop in the lung in association with mediastinal lymph node enlargement.

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Describe imaging manifestations of ankylosing spondylitis:
What condition does this simulate?

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-Approximately 1% to 2% of individuals with ankylosing spondylitis develop pulmonary disease in the form of upper lobe pulmonary fibrosis.
-The fibrotic changes are commonly associated with the development of bullae and cavities, which are prone to mycetoma formation with Aspergillus.
-The diagnosis should be suspected in a young to middle-aged man with characteristic spine changes (kyphosis, spinal ankylosis) seen in association with abnormally increased lung volumes and upper lobe fibrobullous disease, the latter of which simulates postprimary fibrocavitary TB.

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Name all the chronic idiopathic interstitial pneumonias:

Back 83

"All Chronic Interstitial Lung Diseases aRe Nonspecific"
-AIP
-COP
-IPF/UIP
-LIP
-DIP
-RB-ILD
-NSIP

Front 84

What does UIP/IPF look like on chest x-ray?

Back 84

-The earliest radiographic changes are bibasilar fine to medium reticular opacities or ground-glass density
-As the disease progresses, a coarse reticular or reticulonodular pattern is seen, which almost invariably leads to the formation of honeycomb cysts (3 to 10 mm in diameter) and progressive loss of lung volume.
-Extensive pulmonary fibrosis may be associated with findings of pulmonary arterial hypertension.
-Upper lobe bullae may be seen and predispose to the development of spontaneous pneumothorax.

Front 85

What does UIP/IPF look like on CT?

Back 85

-HRCT findings in UIP differ with the stage of the disease and vary from one lung region to another.
-Patients with active inflammatory areas of disease show areas of ground-glass density on HRCT.
-As fibrosis develops, findings include irregular septal or subpleural thickening (in contrast to the smooth septal thickening seen with edema or lymphangitic spread of carcinoma), intralobular lines, irregular interfaces, honeycombing, and traction bronchiectasis
-The changes are typically most severe in the peripheral and basal portions of the lungs, which can be helpful in differential diagnosis
-Mildly enlarged mediastinal lymph nodes are often seen.
-There is an increased incidence of bronchogenic carcinoma, with adenocarcinoma the most common histologic subtype.

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How do patients with AIP present clinically?

Back 86

-Patients with AIP typically present with a brief history of cough, fever, and dyspnea that progresses rapidly to severe hypoxemia and respiratory failure requiring mechanical ventilation.
-The pathologic manifestations of AIP are those of ARDS, and the disease has been termed idiopathic ARDS.
-As in other forms of ARDS, mortality rates range from 60% to 90%.

Front 87

Describe imaging manifestations of AIP:

Back 87

-Chest radiographs and HRCT scans show findings of ARDS, with diffuse ground-glass opacity and consolidation with air bronchograms
-On CT, there is often a gradient of increasing density from anterior to posterior lung.
-Linear opacities, honeycombing, and traction bronchiectasis are uncommon.
-Fibrosis can develop but tends to stabilize and does not progress beyond the recovery phase.

Front 88

What is COP also known as?

Back 88

Idiopathic bronchiolitis obliterans with organizing pneumonia (BOOP)

Front 89

Describe imaging manifestations of COP:

Back 89

-It is a disorder characterized by the widespread deposition of granulation tissue (fibroblasts, collagen, and capillaries) within peribronchiolar airspaces and bronchioles.
-Radiographs in patients with COP reveal patchy bilateral airspace or ground-glass opacities, with some patients showing scattered nodular opacities.
-The most common HRCT findings are patchy consolidation or ground-glass opacity with either a subpleural or peribronchial pattern of distribution
-Small ill-defined peribronchial nodules are seen less commonly.
-Bronchiectasis and bronchial wall thickening are commonly seen in the involved areas of lung.

Front 90

What sorts of things are associated with BOOP?

Back 90

Most cases of BOOP are idiopathic (i.e., COP), but a number of conditions have been associated with this disorder. These include viral infection (influenza, adenovirus, measles); toxic fume inhalation (sulfur dioxide, chlorine); collagen vascular disease (rheumatoid arthritis and SLE); organ transplantation (bone marrow, lung, and heart-lung); drug reactions; and chronic aspiration.

Front 91

Describe imaging manifestations of RB-ILD:

Back 91

-Respiratory bronchiolitis is a disorder seen only in cigarette smokers and is characterized by inflammation within and around the respiratory bronchioles.
-Some authors have suggested that RB-ILD is an early form of DIP.
-The chest radiograph is normal in up to 21% of cases of RB-ILD.
-Diffuse linear and nodular opacities are often seen, as is bibasilar atelectasis.
-The most common HRCT findings are scattered ground-glass opacities and small centrilobular nodules, often with an upper lobe–predominant distribution
-Linear opacities are rare and honeycombing is not seen.
-Emphysema is often a concomitant finding.

Front 92

Describe imaging manifestations of DIP:

Back 92

-DIP is like UIP but patients are younger, heavy smokers, and the disease is more responsive to steroids
-DIP cannot be reliably distinguished from UIP on x-ray
-The typical radiographic findings in DIP are bibasilar reticular opacities with normal or minimally diminished lung volumes.
-Ground-glass opacities are seen in only 33% of cases.
-Up to 22% of patients have a normal chest radiograph.
-HRCT shows ground-glass opacities, most often within the peripheral aspects of the bases
-Irregular linear opacities, honeycombing, and traction bronchiectasis can be seen but are much less common than in UIP.
-Ground-glass abnormalities often improve or completely resolve with corticosteroid therapy.

Front 93

What is NSIP?
What does it look like on imaging?

Back 93

-NSIP is a recently introduced entity, used to describe interstitial pneumonias that cannot be otherwise classified as UIP, AIP, COP, RB-ILD, or DIP.
-Many cases of NSIP are seen in association with collagen vascular disease or as drug reactions.
-Pathologists generally divide NSIP into cellular and fibrotic forms of disease, with correlative findings on HRCT.
-Those with cellular NSIP show areas of ground-glass and consolidation on HRCT in a peripheral and lower zone distribution
-Bronchial dilatation and linear opacities are more typical of the fibrotic form of NSIP, but in distinction to UIP, honeycombing is rare.
-While cellular NSIP is usually responsive to steroids, fibrotic NSIP has a poor prognosis, similar to that of UIP.

Front 94

Describe pulmonary manifestations of NF-1:

Back 94

-Parenchymal lung disease is seen in approximately 20% of patients with NF 1.
-The findings include diffuse interstitial fibrosis and bulla formation.
-The interstitial fibrosis is predominantly lower zonal and bilaterally symmetric.
-Bullae usually develop in the upper zones, with asymmetric involvement of the lungs.

Front 95

Describe pulmonary manifestations of tuberous sclerosis:

Back 95

-Pulmonary involvement in TS is rare and is seen in approximately 1% of cases.
-Patients with pulmonary TS tend to be older and have a lower incidence of seizures and mental retardation.
-The pulmonary involvement is indistinguishable clinically, pathologically, and radiographically from that seen in LAM.
-Radiographically, there are symmetric bilateral reticular or reticulonodular opacities.
-In the later stages of disease, a pattern of coarse reticular or small cystic opacities may be seen.
-The cysts are uniform in size and <1 cm in diameter.
-HRCT is best at depicting the presence of thin-walled pulmonary cysts and can help detect associated extrapulmonary abnormalities, including renal angiomyolipomas and periventricular tubera.
-A helpful feature in distinguishing TS from other chronic interstitial lung diseases is the normal to increased lung volumes in patients with TS caused by small airways obstruction and expiratory air trapping.
-In distinction to EG of lung and sarcoidosis, which have a predominant upper zone distribution of disease, pulmonary TS tends to affect the entire lung uniformly.
-Pneumothorax is common and results from the rupture of a subpleural cyst.
-Pleural effusions are uncommon.
-The pulmonary involvement often leads to pulmonary arterial hypertension and cor pulmonale, which are associated with a high mortality.

Front 96

How do patients with LAM present clinically?

Back 96

-The patient with LAM is typically a woman of childbearing age who presents with progressive dyspnea or a spontaneous pneumothorax.
-Hemoptysis may be seen in some patients, presumably related to pulmonary venous obstruction by the smooth muscle proliferation.

Front 97

Describe xray and CT findings in LAM:
What are the major differential considerations?

Back 97

-The chest radiograph may be normal early in the disease.
-Eventually, symmetric bilateral fine reticular or reticulonodular opacities are seen.
-The late radiographic pattern is one of cysts and honeycombing; the cysts tend to have thinner walls than those seen with IPF or NF
-As in TS, the lung volumes are typically normal or increased.
-Large, recurrent chylous pleural effusions may be unilateral or bilateral.
-Spontaneous pneumothorax is also a common finding and may be bilateral.

-HRCT demonstrates thin-walled cysts distributed throughout the lungs
-In less severely involved areas, the intervening lung is normal.
-Interlobular septal thickening is generally mild or absent.
-Although thin-walled cysts are seen in a variety of other diseases, most notably emphysema and EG, the HRCT findings, when seen in a patient with a characteristic history (a woman with dyspnea, spontaneous pneumothorax, and chylous pleural effusions) are diagnostic

Front 98

What are the three major patterns of amyloid deposition within the lungs and airways?

Back 98

There are three major patterns of amyloid deposition within the lungs and airways: tracheobronchial, nodular parenchymal, and diffuse parenchymal (alveolar septal). In most cases these patterns occur independently, but there can be overlap between them.

Front 99

Describe imaging findings in cases of chronic/recurrent aspiration pneumonia:

Back 99

-Patients who repeatedly aspirate may develop chronic interstitial abnormalities on chest radiographs.
-With repeated episodes of aspiration over months to years, a residuum of irregular reticular interstitial opacities may persist, probably representing peribronchial scarring.
-A reticulonodular pattern may be seen as the result of granulomas forming around food particles.
-These chronic interstitial abnormalities can be observed between episodes of acute aspiration pneumonitis.

Front 100

What is a pneumoconiosis?
How do they differ from the other inhalational lung diseases?

Back 100

-The term pneumoconiosis is used to describe the nonneoplastic reaction of the lungs to inhaled inorganic dust particles
-The inorganic dust pneumoconioses result from the inhalation and retention of asbestos, silica, or coal particles within the lung.
-With time, the accumulation of these particles leads to two types of pathologic reaction that may be seen alone or in combination: fibrosis, which may be focal and nodular or diffuse and reticular; and the aggregation of particle-laden macrophages.

-Organic dust inhalational syndromes are not associated with the retention and accumulation of particles within the lungs.
-Instead, the organic dusts induce a hypersensitivity reaction known as hypersensitivity pneumonitis or extrinsic allergic alveolitis.