diagnostic imaging of diffuse lung lesions

ChestDiffuse Lung Lesions

Mohamed Zaitoun

Assistant Lecturer-Diagnostic Radiology Department , Zagazig University Hospitals

EgyptFINR (Fellowship of Interventional

Neuroradiology)-Switzerlandzaitoun82@gmail.com

Knowing as much as possible about your enemy precedes successful battle

and learning about the disease process precedes successful management

Diffuse Lung Lesionsa) Reticular Interstitial Patternb) Ground Glass Patternc) Nodular Patternd) Cystic Patterne) Mosaic Pattern

a) Reticular Interstitial Pattern :1-Definition2-Description3-Etiology

1-Definition :-Linear shadows (multiple lines) appearing

as mesh or net-It can either mean a plain film or HRCT/CT

feature

2-Description :-Interstitial lung disease -Diffuse lung pathology showing multiple

widespread reticular infiltrations+ Peribronchial cuffing (bronchial wall thickening +

perivascular wall thickening)+ Septal lines (Kerley B) : short lines

perpendicular to the pleura+ Honey combing : multiple peripheral and

subpleural cysts (mm-cm) , thick walls+ Traction bronchiectasis

-N.B. :Causes of septal (Kerley B) lines :a) Pulmonary Venous Engorgement :1-LVF2-MS3-PVODb) Lymphatic / Interstitial Infiltration :1-Lymphangitis carcinomatosis2-Pneumoconiosis3-Sarcoidosis4-Idiopathic bronchiectasis5-Erdheim-Chester disease (ECD) 6-Diffuse pulmonary hemorrhage7-Diffuse pulmonary lymphangiomyomatosis8-Congenital lymphangiectasia9-Alveolar proteinosis10-Alveolar microlithiasis11-Amyloidosis

Honeycombing + Traction Bronchiectasis

Honeycombing

-Interstitial lung disease sparing (e.g. apex , lower lobe , etc) :

*Pneumonia is mainly peripheral with clear center*Fibrosis (no sparing)-Interstitial pulmonary edema (enlarged cardiac

shadow mainly left ventricle)-Hilar lymph nodes + Interstitial lung disease, if :a) Symmetrical >>> Sarcoidosisb) Asymmetrical >>> Lymphangitis carcinomatosis

3-Etiology :1-Idiopathic Interstitial Pneumonia2-Interstitial Fibrosis (Asbestosis)3-Interstitial pulmonary Edema4-Drug Induced5-Collagen Vascular Disease6-Radiation Induced7-With Adenopathy (Sarcoidosis or Lymphangitis

Carcinomatosis)

1-Idiopathic Interstitial Pneumonia (IIP) :a) Usual Interstitial Pneumonia (UIP)b) Non-specific Interstitial Pneumonia (NSIP)c) Cryptogenic Organizing Pneumonia (COP) d) Respiratory bronchiolitis-interstitial lung disease

(RB-ILD)e) Desquamative Interstitial Pneumonia (DIP)f) Lymphocytic Interstitial Pneumonia (LIP)g) Acute Interstitial Pneumonia (AIP)

a) Usual Interstitial Pneumonia (UIP) : Honeycombing-Also known as Idiopathic pulmonary fibrosis (IPF)-Apicobasal gradient is even better seen on high-resolution

CT images-Together with subpleural reticular opacities and

macrocystic honeycombing combined with traction bronchiectasis, the apicobasal gradient represents a trio of signs that is highly suggestive of UIP

-Therefore, UIP should be considered in patients who present with low lung volumes, subpleural reticular opacities, macrocystic honeycombing, and traction bronchiectasis, the extent of which increases from the apex to the bases of the lungs

Distribution of UIP, the distribution is subpleural with an apicobasal gradient (red area in a), CT shows honeycombing (green areas in c), reticular opacities (blue areas in c), traction bronchiectasis (red area in c), and focal ground-glass opacity (gray area in c)

Honey combing-Defined by the presence of small cystic spaces

with irregularly thickened walls composed of fibrous tissue

-Honeycomb cysts often predominate in the peripheral and subpleural lung regions regardless of their cause

-Subpleural honeycomb cysts typically occur in several contiguous layers, this finding can allow honeycombing to be distinguished from paraseptal emphysema in which subpleural cysts usually occur in a single layer

Honeycombing & traction bronchiectasis in UIP

Honeycombing comprises reticular densities caused by the thick walls of the cysts.Whenever you see a chest film with long standing reticulation with a lower lobe and peripheral preference

A, Unenhanced axial high-resolution CT through left mid (A) and lower (B) lung show peripheral honeycombing, which is greatest in lower lobe, accompanied by traction bronchiectasis and scattered peripheral reticular opacities. Honeycombing is most prominent feature in this patient, typical for idiopathic pulmonary fibrosis

b) Non-specific Interstitial Pneumonia (NSIP) : Subpleural Ground-glass

-NSIP is less common than UIP -In non-smokers-High-resolution CT typically reveals a subpleural and

rather symmetric distribution of lung abnormalities-The most common manifestation consists of patchy

ground-glass opacities combined with irregular linear or reticular opacities and scattered micronodules

-In advanced disease, traction bronchiectasis and consolidation can be seen; however, ground-glass opacities remain the most obvious high-resolution CT feature in the typical patient with NSIP

 Distribution of NSIP, the distribution is subpleural with no obvious gradient

(red area in a), CT shows ground-glass opacity (gray areas in c), irregular linear and reticular opacities (blue areas in c), micronodules (red areas in c), and microcystic honeycombing (green areas in c)

NSIP in a 60-year-old woman with mild dyspnea and fatigue, high-resolution CT image of the lower lungs shows bilateral subpleural ground-glass opacities (arrowhead) and irregular linear opacities (arrow)

NSIP in a 53-year-old man with mild dyspnea, coronal CT image shows diffuse lung involvement consisting of peripherally located irregular linear opacities with ground-glass opacities (arrows), small cystic lesions are seen (arrowhead)

48-year-old woman with scleroderma, cough, and dyspnea and biopsy-proven nonspecific interstitial pneumonia, high-resolution CT through lower lungs shows scattered ground-glass opacities that are relatively symmetric in distribution, accompanied by bronchiectasis, honeycombing is absent, note dilated esophagus, finding associated with scleroderma

(a) UIP is characterized by heterogeneous lung abnormalities consisting of subpleural honeycombing (arrowhead), reticular opacities, and traction bronchiectasis, (b) NSIP demonstrates homogeneous lung involvement with predominance of ground-glass opacity combined with sub-pleural linear opacities and micronodules. The microcysts in NSIP (arrowhead) are much smaller than the honeycombing in UIP

c) Cryptogenic Organizing Pneumonia (COP) : Ground-glass (peribronchial, peripheral not subpleural) & Consolidation

-The lung abnormalities show a characteristic peripheral or peribronchial distribution, and the lower lung lobes are more frequently involved

-In some cases, the outermost subpleural area is spared-Typically, the appearance of the lung opacities varies from

ground glass to consolidation; in the latter, air bronchograms and mild cylindrical bronchial dilatation are a common finding

-In the appropriate clinical context, that is, consolidation that increases over several weeks despite antibiotics, the CT features of COP are often suggestive    

Distribution of COP, the distribution is peripheral or peribronchial with a basal predominance (red areas in a), CT shows consolidation with air bronchograms (dark gray areas in c), ground-glass opacities (light gray areas in c), linear opacities (blue areas in c), and mild bronchial dilatation (red areas in c)

COP in a 54-year-old woman, coronal CT image shows extensive bilateral peribronchial consolidation and ground-glass opacities (arrows). An endotracheal tube is present (arrowhead), indicating the need for mechanical ventilation

COP in a 69-year-old man, high-resolution CT image shows peripherally located consolidation with air bronchograms and sparing of the subpleural space (arrow)

d) Respiratory Bronchiolitis-Interstitial Lung Disease (RB-ILD) : Centrilobular nodules + ground-glass

-RB-ILD is a smoking-related interstitial lung disease and is thought to represent an exaggerated and symptomatic form of the histologically common and incidental finding of respiratory bronchiolitis

-Because of the significant overlap in clinical, imaging, and histologic features between RB-ILD and DIP, these entities are considered a pathomorphologic continuum, representing different degrees of severity of the same disease process

-The key high-resolution CT features of RB-ILD are centrilobular nodules in combination with ground-glass opacities and bronchial wall thickening

Distribution of RB-ILD, RB-ILD has an upper lung predominance (red area in a), CT shows ground-glass opacity (gray area in c) and centrilobular nodules (red areas in c)

RB-ILD in a 44-year-old woman with a 20 pack-year smoking history, high-resolution CT image of the upper lung lobes shows centrilobular nodules (white arrows) and patchy ground-glass opacities (black arrow), mild coexisting centrilobular emphysema is seen (arrowhead)

50-year-old man with long-standing history of heavy cigarette smoking, dyspnea, cough, and smoking-related interstitial lung disease, proven at biopsy, unenhanced axial CT image through mid to lower lungs shows diffuse centrilobular ground-glass nodules bilaterally

e) Desquamative Interstitial Pneumonia (DIP) : Diffuse ground-glass

-DIP is strongly associated with cigarette smoking and is considered to represent the end of a spectrum of RB-ILD

-At high-resolution CT, DIP is characterized by diffuse ground-glass opacities

-Usually, there is a peripheral and lower lung lobe predominance

-Other frequent CT findings include spatially limited irregular linear opacities and small cystic spaces, which are indicative of fibrotic changes

-Despite differences in the CT appearance of RB-ILD and DIP, imaging findings may overlap and may be indistinguishable from each other, to improve diagnostic accuracy, lung biopsy is required in all cases of suspected RB-ILD or DIP

 Distribution of DIP, DIP has a peripheral predominance (red areas in a),

CT shows ground-glass opacity (gray area in c), irregular linear opacities (blue areas in c), and cysts (green areas in c)

DIP in a 55-year-old man, high-resolution CT image of the lower lung lobes shows extensive bilateral ground-glass opacities (arrowhead), coexisting moderate bronchial wall thickening is present (arrow)

DIP in a 43-year-old man with a history of smoking, high-resolution CT image of the lower lung zones shows patchy ground-glass opacities in both lungs, predominantly in the subpleural region (arrowheads), small cystic spaces are present in these areas (arrow)

49-year-old woman with persistent and progressive cough, dyspnea, and hypoxemia, prompting biopsy of her lungs, which revealed chronic desquamative interstitial pneumonia (DIP) related to extensive cigarette smoking history, CT images through mid and lower lungs show patchy ground-glass opacities in all lobes of both lungs with peripheral predilection accompanied by lower lobe bronchial wall thickening, note small cysts scattered mostly in right lung in regions of ground-glass attenuation, finding that can occur in DIP

f) Lymphocytic Interstitial Pneumonia (LIP) : Female + Sjogren syndrome + ground-glass + perivascular cysts

-As an idiopathic disease, LIP is exceedingly rare-It is far more common as a secondary disease in association

with systemic disorders, most notably Sjögren syndrome, human immunodeficiency virus infection, and variable immunodeficiency syndromes

-More common in women than in men-The dominant high-resolution CT feature in patients with LIP

is ground-glass attenuation-Another frequent finding is thin-walled perivascular cysts, in

contrast to the subpleural, lower lung cystic changes in UIP, the cysts of LIP are usually within the lung parenchyma throughout the mid lung zones and presumably result from air trapping due to peribronchiolar cellular infiltration

-In combination with ground-glass opacities, these cysts are highly suggestive of LIP

Distribution of LIP, the distribution is diffuse (red area in a), CT shows ground-glass opacity (gray area in c) and perivascular cysts (green areas in c)

LIP in a 47-year-old woman, high-resolution CT image shows diffuse ground-glass opacity (arrow) with multiple perivascular cysts (arrowheads) and reticular abnormalities (*)

58-year-old woman with Sj??gren syndrome, persistent dyspnea, and biopsy-proven lymphoid interstitial pneumonia, unenhanced axial CT image through mid lungs reveals centrilobular ground-glass nodule

73-year-old woman with Sjogren syndrome symptoms, including dyspnea and arthralgias, and biopsy-proven lymphoid interstitial pneumonia (LIP), contrast-enhanced coronal reformatted image through lungs shows numerous thin-walled cysts mostly located adjacent to blood vessels, these perivascular cysts are identified in most patients with LIP

71-year-old woman with Sjogren syndrome, chest pain, cough, dyspnea, and biopsy-proven lymphoid interstitial pneumonia (LIP)., contrast-enhanced axial CT image shows both perivascular cysts and lower lobe ground-glass opacities, combination of findings that strongly supports diagnosis of LIP

g) Acute Interstitial Pneumonia (AIP) : Acute onset + early (ground-glass), late (fibrosis)

-AIP is the only entity among the IIPs with acute onset of symptoms, in most cases of AIP, the clinical and imaging criteria for acute respiratory distress syndrome are fulfilled

-High-resolution CT features of AIP are similar to those of acute respiratory distress syndrome; however, patients with AIP are more likely to have a symmetric, bilateral distribution with a lower lobe predominance

-The costophrenic angles are often spared-In the early phase of AIP (Exudative phase), ground-glass

opacities are the dominant CT pattern-In the late phase of AIP (Fibrotic phase), architectural

distortion, traction bronchiectasis, and honeycombing are the most striking CT features and are more severe in the nondependent areas of the lung

Distribution of AIP, AIP has a basal predominance (red area in a), CT shows airspace consolidation (dark gray areas in c), ground-glass opacities (light gray areas in c), and bronchial dilatation (red areas in c)

Exudative phase of AIP in a 22-year-old man, high-resolution CT image shows bilateral ground-glass opacities (arrowheads) and consolidation (arrow) in the dependent areas of the lungs, the anterior zones of the lungs are relatively spared

Fibrotic phase of AIP in a 53-year-old woman who survived the acute phase of the disease, CT image shows fibrotic changes with traction bronchiectasis and architectural distortion predominantly in the nondependent areas of the lungs (arrow), a coexisting right pleural effusion is seen (arrowhead)

2-Interstitial Fibrosis (Asbestosis) :-Asbestosis refers exclusively to asbestos-related interstitial

pulmonary fibrosis-The changes of asbestosis are more pronounced in the

lower lobes and subpleurally but often extend to involve the middle lobe and lingula, upper lobes can be involved in advanced cases

-Honeycombing, as in other fibrotic lung diseases, can occur in advanced disease

-Features on chest radiographs include ground-glass opacification, small nodular opacities, “shaggy” cardiac silhouette, and ill-defined diaphragmatic contours, it has been reported that 80% of patients with asbestosis have coexistent pleural disease at chest radiography, fibrous bands are sometimes seen to radiate inward from the pleura 

(a) PA radiograph of a patient with asbestosis shows “shaggy” mediastinal and diaphragmatic contours, (b) Localized view of the lung bases of the same patient further illustrates the diffuse interstitial opacification

PA radiograph shows diffuse fine nodular and reticular opacification with irregularity of mediastinal and diaphragmatic contours, the costophrenic angles are blunted because of pleural thickening

PA radiograph of an asbestos-exposed person shows parenchymal bands radiating in from the pleura in both mid zones (arrows), diffuse pleural thickening is predominantly left-sided

-HRCT :*An early feature is a subpleural curvilinear opacity, this

finding represents peribronchiolar fibrosis*Parenchymal band-shaped opacities project in from the

pleura and represent fibrosis along bronchovascular sheaths or interlobular septa

*Other features that have been reported include ground-glass opacification (due to mild alveolar wall fibrosis beyond the resolving power of CT, subpleural nodular or dotlike opacities, thickening of interlobular septa, and honeycombing  

Axial high-resolution CT scan shows a subpleural curvilinear opacity (arrows) thought to represent peribronchiolar fibrosis

High-resolution CT scan obtained with the patient in a prone position shows early subpleural curvilinear opacity (arrows)

HRCT scan shows bilateral parenchymal bands (arrows)

HRCT scan shows subpleural areas of ground-glass attenuation (arrows)

HRCT scan shows subpleural nodular and dotlike opacities (solid wide arrows) that coalesce to form subpleural curvilinear lines (open arrows), there are also interlobular (solid thin arrows) and intralobular (arrowheads) interstitial lines

HRCT scan shows interlobular septal thickening (arrowheads)

HRCT scan depicts subpleural honeycombing (open arrows), interlobular septal thickening (solid arrows), and subpleural nodular opacities (arrowheads)

HRCT scan shows subpleural honeycombing

-N.B. :Asbestos exposure causes a variety of

manifestations :a) Pleura :1-Pleural plaques (hyalinized collagen)2-Diffuse thickening3-Benign pleural effusion (most common

manifestation)4-Pleural calcification

PA radiograph shows extensive calcified pleural plaques (arrows) that affect the chest wall, diaphragm, and pericardium, the costophrenic angles and apices are spared

PA radiograph of an asbestos-exposed patient shows a right-sided pleural effusion (arrows)

(a) Axial CT scan of an asbestos-exposed person shows a left-sided pleural effusion (arrow), (b) Axial CT scan obtained 2 years later shows circumferential pleural thickening that extends into the major fissure (straight arrow) and contains flecks of calcification (curved arrow)

 (a) PA radiograph shows pleural thickening with obliteration of the left costophrenic angle (arrows), there are also some associated linear parenchymal opacities (arrowheads), (b) Axial CT scan of the same patient shows circumferential pleural thickening (arrows)

CT scans obtained with soft-tissue window settings show calcified anterior and paravertebral plaques (arrows)

b) Lung :1-Interstitial fibrosis (asbestosis)2-Rounded atelectasis with comet tail sign of

vessel leading to atelectatic lung3-Fibrous massesc) Malignancy :1-Malignant mesothelioma2-Bronchogenic carcinoma3-Carcinoma of the larynx4-GI malignancies

Round atelectasis, (a) PA radiograph shows an opacity in the right middle zone (arrows), (b) Axial CT scan of the same patient shows a peripheral mass that abuts thickened pleura, with comet tail distortion of the vascular structures (arrows)

Axial CT scan shows an ovoid mass, pleural thickening, and linear comet tail of rounded atelectasis

PA radiograph shows left-sided lobulated thickening (arrowheads) and pleural effusion (arrow), findings characteristic of malignant mesothelioma

Axial CT scan of a patient with a right-sided mesothelioma shows a benign pleural plaque (arrow) engulfed by tumor tissue

Axial CT scan shows a right-sided mesothelioma with extension along the major fissure (arrow) and chest wall invasion (arrowhead)

Axial CT scan of a patient with a left-sided malignant mesothelioma shows contraction of the hemithorax and chest wall invasion (arrow)

Axial CT scan of a patient with a right-sided mesothelioma shows invasion and encasement of the pericardium (arrowheads)

Axial CT scan shows a left-sided mesothelioma with mediastinal encasement and lymphadenopathy (arrowheads)

Axial CT scan shows a large left lower lobe carcinoma in a patient with asbestos-related plaques (arrows)

**N.B. : Fibrotic changesD.D. of lower lobe fibrotic changes :1-Idiopathic pulmonary fibrosis 2-End-stage asbestosis3-NSIP (nonspecific interstitial pneumonia)D.D. of upper lobe fibrotic changes :Although IPF is the most common cause of pulmonary

fibrosis, fibrosis is primarily affecting the upper lobe should raise concern for an alternative diagnosis, such as :

1-End-stage sarcoidosis2-Chronic hypersensitivity pneumonitis3-End-stage silicosis

3-Interstitial Pulmonary Edema :-Only in early stages-Late shows ground glass opacities

Increased hydrostatic pressure edema in a 33-year-old man with acute myelocytic leukemia who was admitted for fluid overload with renal and cardiac failure, successive chest radiographs demonstrate progressive lobar vessel enlargement, peribronchial cuffing (arrows in b), bilateral Kerley lines (arrowheads in c), and late alveolar edema with nodular areas of increased opacity, the fluid overload is confirmed by the increasing size of the azygos vein

4-Drug Induced Interstitial Disease :-Radiographic Features : as before

5-Collagen Vascular Disease :-The two thoracic manifestations with the greatest

clinical importance in patients with collagen vascular diseases are :

1-Interstitial Lung Disease2-Pulmonary Arterial Hypertension

1-Patterns of Interstitial Lung Disease :1-Usual interstitial pneumonia (UIP)2-Nonspecific interstitial pneumonia (NSIP)3-Cryptogenic organizing pneumonia (COP)4-Diffuse alveolar damage (DAD)5-Lymphocytic interstitial pneumonia (LIP)6-Apical fibrosis

2-Pulmonary Arterial Hypertension :a) Definitionb) Incidencec) Radiographic Features

a) Definition :-Pulmonary arterial hypertension is defined

by a mean resting pulmonary artery pressure of ≥25 mm Hg and a pulmonary capillary wedge pressure of ≤15 mm Hg

b) Incidence :-Patients with collagen vascular diseases are

considered to have a higher risk for pulmonary arterial hypertension which may occur in isolation or in combination with interstitial lung disease

-Pulmonary arterial hypertension is more common in patients with progressive systemic sclerosis and mixed connective tissue disease, it is less common in systemic lupus erythematosus and even rarer in patients with rheumatoid arthritis, polymyositis or dermatomyositis or Sjögren syndrome

c) Radiographic Features :-Increased diameter of the pulmonary arterial trunk

(>2.9 cm), the main pulmonary arteries and their segments and in more advanced cases , the right heart chambers and azygos-hemiazygos venous system

-Contrast material reflux into the inferior vena cava and hepatic veins , a result of elevated right heart pressures also may be seen

-Associated pericardial effusion is a common finding that portends a poor prognosis

(a) Frontal chest radiograph shows a prominent main pulmonary artery (arrow) , dilated right interlobar artery (arrowhead) and pruning of peripheral pulmonary vascularity , (b) Lateral chest radiograph shows filling of the retrosternal airspace (arrow) a result of right ventricular dilatation , the right ventricle is in contact with more than one-third of the distance from the sternodiaphragmatic angle (black arrowhead) to the point where the trachea meets the sternum (white arrowhead)

 Yellow arrow shows enlarged right main pulmonary artery , red arrow shows the enlarged left pulmonary artery

-Vascular signs of pulmonary hypertension

-Axial multidetector CT angiogram shows dilatation (29 mm or more) of the main pulmonary artery

-The ratio of the main pulmonary arterial diameter to that of the ascending aorta is also greater than or equal to 1, another useful sign of pulmonary hypertension

-(A) Markedly enlarged pulmonary arteries with tiny branching smaller vessels

-(B) Enlarged right ventricle and the smaller left ventricle , the septum is pushed towards the left ventricle due to very high pressure inside the right ventricle

Cardiac features of pulmonary hypertension. (a) CTA shows that the right ventricular myocardium (white arrow) is more than 4 mm thick , a finding consistent with right ventricular hypertrophy. Straightening of the interventricular septum (black arrow) also is seen. (b) CTA shows right ventricular dilatation which is defined as a diameter ratio (the ratio of the right ventricular diameter [black arrow] to the left ventricular diameter [white arrow]) greater than 1:1 at the midventricular level , Leftward bowing of the interventricular septum also is seen. (c) CTA shows reflux of contrast material into the inferior vena cava which is dilated and hepatic veins (arrow)

6-Radiation Induced Interstitial Lung Disease :

-Radiation induced pulmonary fibrosis-Radiographic Features : as before 

7-With Adenopathy (Sarcoidosis or Lymphangitis Carcinomatosis) :

a) Sarcoidosis :1-Incidence2-Classification3-Radiographic Features

1-Incidence :-Pulmonary manifestations are present in

approximately 90% of patients-Pulmonary sarcoidosis most commonly

affects patients between 20 and 40 years of age although it is seen essentially at any age

-There is a slight female predominance

2-Classification :-May be classified on a chest radiograph into 5

stages :Stage 0 : normal chest radiographStage I : hilar or mediastinal nodal enlargement

onlyStage II : nodal enlargement and parenchymal

diseaseStage III : parenchymal disease onlyStage IV : end-stage lung (pulmonary fibrosis)

Stage I

Stage II

Stage III

Stage IV

3-Radiographic Features :1-Lymph Node Enlargement2-Reticulonodular Opacities3-Air Space Like Opacities (Alveolar

Sarcoidosis)4-Peripheral Cavitation , atelectasis &

effusion5-End Stage Fibrosis

1-Lymph Node Enlargement :-The most common manifestation is bilateral

hilar and mediastinal nodal enlargement-Classically the distribution is of bilateral

hilar and right paratracheal nodal enlargement which is known as the 1-2-3 sign or Garland triad

- calcification of intrathoracic nodes is seen in 20% of cases after 10 years

2-Reticulonodular Opacities :-Most common : 75-90% of stage II and III

cases-Middle and upper zone distribution-Bilateral and symmetric-Nodularity may be prominent and appear

as miliary opacities

Nodular peribronchovascular interstitial thickening in a patient with sarcoidosis , numerous small nodules surround central bronchi and vessels

3-Air Space Like Opacities (Alveolar Sarcoidosis) :

-Simulating acute inflammatory disease4-Peripheral Cavitation , Atelectasis & Effusion:-Rare5-End Stage Fibrosis :-Permanent coarse linear opacities-Typically radiating laterally from the hilum into the

adjacent upper and middle zones

Stage I

Stage II

1-Lymphadenopathy and ground glass appearance of the lungs, 2-Lymphadenopathy, 1-2-3 sign, 3-Bulky lymphadenopathy, 4-1-2-3 sign, 5-Nodular lung pattern , no lymphadenopathy, 6-Hilar and paratracheal lymphadenopathy

b) Lymphangitis Carcinomatosis :1-Incidence2-Radiographic Features

1-Incidence :-Is the term given to tumor spread through the lymphatics

of the lung and is most commonly seen secondary to adenocarcinoma such as :

1-Breast cancer , most common2-Lung cancer (bronchogenic adenocarcinoma)3-Colon cancer4-Stomach cancer5-Prostate cancer6-Cervical cancer7-Thyroid cancer

2-Radiographic Features :-Typically the appearance is that

of interlobular septal thickening most often nodular and irregular although smooth thickening may also sometimes be seen

-Mediastinal and/or hilar lymphadenopathy-Peribronchovascular thickening -Pleural effusions

A central bronchogenic carcinoma (blue arrow) is producing unilateral interstitial edema (blue circles) characteristic of lymphangitic carcinomatosis with a pleural effusion(red arrow) , thickening and irregularity of the bronchovascular bundles (yellow arrow) and thickening of the interlobular septa (light blue arrow)

b) Ground Glass Pattern :1-Definition2-Description3-Etiology

1-Definition :-Air space filling disease-A hazy area of increased attenuation in the lung with

preserved bronchial and vascular markings-Filling of the alveolar spaces with pus , edema ,

hemorrhage , inflammation or tumor cells -Ground glass in itself is very unspecific , may be

diagnostic in ;a) AIDS + ground glass = Pneumocystitis cranii pneumoniab) Lung transplant + ground glass = CMV pneumonia or

rejection

2-Description :-Three presentations :a) Ground glass densityb) Nodules (few mm-1 cm)c) Confluent opacities ,frank consolidation

with air bronchogram

3-Etiology :a) Pneumoniab) Pulmonary Edemac) Pulmonary Hemorrhaged) Bronchoalveolar Carcinomae) Alveolar Proteinosis

a) Pneumonia :-Peripherally located lesion-See (Pulmonary Infections & Idiopathic

Interstitial Pneumonia)

b) Pulmonary Edema :-See pulmonary edema

Bat wing edema in a 71-year-old woman with fluid overload and cardiac failure, chest radiograph (a) and high-resolution CT scan (b) demonstrate bat wing alveolar edema with a central distribution and sparing of the lung cortex, the infiltrates resolved within 32 hours

c) Pulmonary Hemorrhage :1-Incidence2-Radiographic Features

1-Incidence :-Diagnosed when there are :1-Hemoptysis2-Anaemia3-Air space opacities on imaging-Divided into :1-Diffuse pulmonary hemorrhage2-Localized pulmonary hemorrhage

Localized Diffuse

2-Radiographic Features :-Appears rapidly and clear within few days-Spare the lung apex & peripheral zones-Looks like pulmonary edema but heart is

normal and no pleural effusion

d) Bronchoalveolar Carcinoma (BAC) :1-Incidence2-Clinical Picture3-Radiographic Findings

1-Incidence :-Sub-group of adenocarcinomas of the lung

accounting for 2-9% of primary lung lesions

-A disease presenting in the 6th and 7th decades with a 3:2 male predominance

2-Clinical Picture :-Nearly half of patients with BAC are asymptomatic

at presentation with cough , chest pain and weight loss most common among those with symptoms

-If the tumor is mucin secreting , a productive cough with abundant mucoid expectoration can be seen

-This classic finding of (marked) bronchorrhea is an uncommon and late finding

3-Radiographic Findings : 3 Patternsa) Solitary Noduleb) Consolidated Formc) Diffuse or Multicentric Form

a) Solitary Nodule :-Usually a well-circumscribed focal mass

located in the periphery of the lung with spiculated borders

-A pleural tag or "tail sign" is common and describes linear strands extending from nodule to pleura

Solitary peripheral nodule with pleural tags

Solitary peripheral nodule with bubblelike lucencies

b) Consolidated Form :-May be segmental or involve an entire lobe-The combination of growth along the air spaces

with the production of mucin may cause the features of airspace consolidation with air-bronchograms

-If a large amount of mucin is present it may cause consolidation of low attenuation and following the administration of I.V. , the vessels will be seen within the consolidation , this is referred to as the CT angiogram sign and is suggestive of BAC

-A characteristic finding of BAC is the presence of bubble like lucencies or pseudocavitation which corresponds to patent small bronchi or air-containing cystic spaces in papillary tumors

Isolated lobar consolidation with bulging of major fissure and cystic air spaces

Isolated lobar consolidation with the angiogram sign

c) Diffuse or Multicentric Form :-Widespread disease in multiple lobes of

both lungs*N.B. :-Classic radiographic findings in BAC

include a solitary spiculated mass with air bronchograms

-Airspace consolidation and a diffuse multicentric presentation are also common

Multinodular pattern with foci of calcifications within one of the nodules

Multinodular pattern with cavitation of some nodules

a) Solitary nodule , 2 cm , note the bubble like lucencies inside the nodule

b) Isolated lobar consolidation , 15 months later , note the angiogram inside the consolidation

c) Contralateral consolidation , 4 months later after left lower lobectomy

e) Alveolar Proteinosis :1-Etiology2-Radiographic Features

1-Etiology :-Alveoli filled by proteineus materiala) Idiopathic (90%)b) Occupationalc) Drug inducedd) Immune compromise

2-Radiographic Features :a) Plain radiography :-Non-specific-batwing pulmonary opacitiesb) HRCT :-Crazy Paving :A combination of ground glass opacity with

superimposed septal thickening-The distribution is typically central with

sparing of the periphery

**N.B. : D.D. of crazy paving :1-Alveolar proteinosis2-Pneumocystitis Jiroveci pneumonia3-Organizing pneumonia4-BAC (mucinous subtype)5-Lipid pneumonia 6-ARDS7-Pulmonary hemorrhage

c) Nodular Pattern :1-Definition2-Description3-Etiology

1-Definition :-Multiple rounded opacities 1-10 mm (miliary

= 1-2 mm)

2-Description :-In most cases small nodules can be placed

into one of three categories : (PCR)a) Random distributionb) Centrilobular distributionc) Perilymphatic distribution

1-Random distribution , nodules are randomly distributed relative to structures of the lung and secondary lobule , nodules can usually be seen to involve the pleural surfaces and fissures but lack the subpleural predominance often seen in patients with a perilymphatic distribution

2-Centrilobular distribution , unlike perilymphatic and random nodules , centrilobular nodules spare the pleural surfaces , the most peripheral nodules are centered 5-10mm from fissures or the pleural surface

3-Perilymphatic distribution , nodules are seen in relation to pleural surfaces , interlobular septa and the peribronchovascular interstitium , nodules are almost always visible in a subpleural location particularly in relation to the fissures

3-Etiology :a) Miliary T.B.b) Fungal Infectionc) Miliary Metsd) Pneumoconiosise) Wegner’s Granulomatosisf) Pulmonary Alveolar Microlithiasis

a) Miliary Pulmonary Tuberculosis :-It represents hematogenous dissemination

of an uncontrolled tuberculous infection-It is seen both in primary and post-primary

tuberculosis-Miliary deposits appear as 1-3 mm diameter

nodules which are uniform in size and uniformly distributed (no calcification)

-Differential Diagnosis of multiple micronodules (0.5-2 mm) :

1-Miliary TB2-Fungal Infection 3-Coal Miner’s Pneumoconiosis4-Sarcoidosis5-Hemosiderosis6-Silicosis7-Siderosis8-Stannosis9-Barytosis

b) Fungal Infection :-Two broad categories :a) Endemic human mycoses (prevalent

only in certain geographic areas) :1-Histoplasmosis2-Coccidioidomycosis3-Blastomycosis

b) Opportunistic mycoses (worldwide in distribution) occur primarily in immunocompromised patients (aspergillosis and cryptococcosis may also occur in immunocompetent hosts)

1-Aspergillosis (invasive)2-Candidiasis3-Cryptococcosis4-Mucormycosis

c) Miliary Mets :1-Thyroid carcinoma2-Renal cell carcinoma3-Breast carcinoma4-Malignant melanoma5-Pancreatic neoplasms6-Osteosarcoma7-Trophoblastic disease

d) Pneumoconiosis :1-Etiology2-Radiographic Features

1-Etiology :-Caused by inhalation of inorganic dust

particles that overwhelm the normal clearance mechanism of the respiratory tract :

1-Silica >>Silicosis2-Coal workers' pneumoconiosis (CWP)3-Asbestose >>Asbestosis

2-Radiographic Features :a) Nodulesb) Progressive Massive Fibrosis c) Other features : with asbestosisPleural thickening , plaquesPleural calcification , diffuse

a) Nodules :-Dense multiple nodules sparing the apex

and the base-Calcification may occur-Egg shell calcification of lymph nodes-Hilar lymph nodes

b) Progressive Massive Fibrosis :-Nodules enlarge and coalesce to form

masses >>progressive massive fibrosis-Bilateral almost symmetrical , almost

always in the upper half of the lung

c) Other features : with asbestosisPleural thickening, plaques (See before)

Calcified plaque

Calcified plaque

Non-calcified plaque

e) Wegner’s Granulomatosis :1-Incidence2-Radiographic Features

1-Incidence :-Systemic granulomatous process with

destructive angiitis involving lung , upper respiratory tract and kidney (necrotizing glomerulonephritis) , Type IV immune mechanism

2-Radiographic Features :-Interstitial lung disease + multiple nodules

with cavitation (common)

f) Pulmonary Alveolar Microlithiasis :1-Incidence2-Radiographic Features3-Differential Diagnosis 

1-Incidence :-Is a rare idiopathic condition characterised

by widespread intra alveolar deposition of spherical calcium phosphate microliths

2-Radiographic Features :-Typically demonstrates sand like

calcification distributed throughout the lungs

-Distribution is bilateral with middle to lower zone predilection

-Black pleura sign (pleura appear as a lucent line lying between the pulmonary infiltrate & the adjacent ribs)

Nearly uniform distribution of typical fine, sandlike mottling in the lungs

The tangential shadow of the pleura is displayed along the lateral wall of the chest as a dark lucent strip (arrows)

Multiple calcific densities in both lungs with thickening and increased density along the fissure and along the mediastinal margin , a black pleural line is noted

3-Differential Diagnosis of multiple small (pin point) micronodules :

1-Post lymphangiography2-Silicosis3-Stannosis (inhalation of tin oxide)4-Barytosis (inhalation of barytes)5-Limestone & marble workers6-Alveolar microlithiasis

d) Cystic Pattern :1-Definition2-Description3-Etiology

1-Definition :-Defined as radiolucent areas with a wall

thickness of less than 4mm

2-Description :-Multiple thin walled air containing lesions 1

cm or more (Not seen by x-rays except for bronchiectasis)

3-Etiology :a) Langerhan’s Cell Histiocytosis (LCH)b) Lymphangioleiomyomatosis (LAM)c) Tuberous Sclerosis (TS)d) Emphysemae) Cystic Bronchiectasisf) Lymphocytic Interstitial Pneumonia (LIP)

a) Langerhan’s Cell Histiocytosis :1-Incidence2-Types3-Radiographic Features4-Differential Diagnosis

1-Incidence :-Is a rare multi-system disease with a wide

and heterogeneous clinical spectrum and variable extent of involvement

-The disease is more common in the pediatric population with a peak incidence between 1 and 3 years of age

2-Types :-Langerhan’s cell histiocytosis consists of three

clinical syndromes :a) Letterer-Siwe disease :-Acute disseminated formb) Hand-Schuller-Christian disease (HSC) :-Chronic disseminated formc) Eosinophilic Granuloma (EG) :-Solitary bone lesion + small cystic spaces in lung

parenchyma

3-Radiographic Features : EG-Solitary bone lesion-Small cystic spaces in lung parenchyma

(spares the lower lung zones)-3 to 10 mm pulmonary nodules-Apical reticulonodular pattern-Pneumothorax , 30 %

4-Differential Diagnosis :-From diffuse lung diseases with preserved lung

volumes :1-LCH2-LAM / Tuberous sclerosis complex3-Cystic fibrosis4-Sarcoidosis5-Idiopathic pulmonary fibrosis with emphysema

b) Lymphangioleiomyomatosis (LAM) :1-Incidence2-Radiographic Features

1-Incidence :-It almost exclusively affects women of child

bearing age

2-Radiographic Features :-Numerous cystic spaces , 90%Size of cysts usually <5 to 10 mmThin walledSurrounded by normal lung-Recurrent pneumothorax , 70%-Chylous pleural effusions , 25%

c) Tuberous Sclerosis (TS) :-Pulmonary involvement of TS includes

Lymphangioleiomyomatosis (LAM) and multifocal micronodular pneumocyte hyperplasia (MMPH)

-AML of the kidney & liver may help in the diagnosis

Pulmonary LAM in a 29-year-old woman, thin-section CT scan demonstrates multiple lung cysts with well-defined thin walls, these cysts are distributed randomly throughout the lung

Pulmonary LAM in a 37-year-old woman, thin-section CT image shows bilateral numerous cysts associated with reticular opacities

Pneumothorax associated with pulmonary LAM in a 37-year-old woman, CT image of the chest demonstrates multiple lung cysts, suggesting pulmonary LAM, pneumothorax can be seen in the right thoracic cavity (arrows)

MMPH in a 19-year-old man, CT scan demonstrates multiple tiny nodules (arrows), with random distribution in the lungs

d) Emphysema :-See Air way diseases

Centrilobular Emphysema

Panlobular Emphysema

Paraseptal Emphysema

Bullous Emphysema

e) Cystic Bronchiectasis :-See Bronchiectasis-More in the lower lobes-Diseases causing cystic bronchiectasis :1-Tracheobronchomegaly :-The trachea is involved2-Cystic Fibrosis :-Upper lung predominance-N.B. : Cystic bronchiectasis always seen with

tubular bronchiectasis

Cystic bronchiectasis

Cystic bronchiectasis

f) Lymphocytic Interstitial Pneumonia (LIP) :

-See before

N.B. : Differential Diagnosis of Pulmonary Cysts

a) Diffuse Lung Diseasesb) Congenitalc) Post-infectived) Hydatid Cyste) Post-traumaticf) Neoplastic

a) Diffuse lung diseases :1-Langerhan’s Cell Histiocytosis2-Lymphangioleiomyomatosis (LAM)3-Tuberous Sclerosis (TS)4-Emphysema5-Cystic Bronchiectasis6-Lymphocytic Interstitial Pneumonia (LIP)

b) Congenital : (See congenital pulmonary lesions)

1-Congenital Pulmonary Adenomatoid Malformation

2-Bronchogenic cyst

c) Post-infective :-Cysts can appear during the first 2 weeks of the

pneumonia and may resolve over several months

1-Staphylococcus aureus : a characteristic feature of childhood staphylococcal pneumonia , developing in 40-60 % of cases

2-Streptococcus pneumonia3-E.Coli4-Klebsiella pneumonia5-Haemophilus influenza

Post infectious pneumatocele, the initial chest x-ray shows consolidation in the right lung, follow up chest done, when the patient was asymptomatic, shows multiple thin walled lucencies in the right lung

(a) Initial CXR shows a dense right upper lobe consolidation, (b) CXR a week later shows a round cyst with thin walls in the right upper lobe

d) Hydatid Cyst :-See Infection

e) Post-traumatic :-Lung laceration, cyst measuring up to 5 cm

in diameter, resolution over time

Air meniscus in the superior aspect of the lesion as a result of the enlarging cyst communicating with an adjacent bronchiole

Water Lilly

f) Neoplastic :1-Following treatment of pulmonary metastases ,

bladder cancer and germ cell tumors , may be visible only on CT

2-Hyalinazing Granulomas :-Rare disorder of unknown etiology but possible

association with infection and autoimmunity-Multiple ill-defined / well-defined nodules & cysts3-Metastatic epithelioid sarcoma

e) Mosaic Pattern :1-Definition2-Description3-Etiology

1-Definition :-Used to describe density differences

between affected and non-affected lung areas , there are patchy areas of black and white lung

2-Description :-Is the description given to the appearance

at CT where there is a patchwork of regions of differing attenuation

-It is a non-specific finding

3-Etiology :a) Obstructive Small Airway Diseaseb) Occlusive Vascular Diseasec) Parenchymal Disease

a) Obstructive Small Airway Disease :-Low attenuation regions are abnormal and

reflect decreased perfusion of the poorly ventilated regions

-e.g. bronchiectasis ,cystic fibrosis & constrictive bronchiolitis (See airway disease)

b) Occlusive Vascular Disease :-Can be termed a mosaic perfusion pattern

in this setting , low attenuation regions are abnormal and reflect relative oligaemia , e.g. chronic pulmonary embolism (See pulmonary embolism)

c) Parenchymal Disease :-High attenuation regions are abnormal and

represent ground-glass opacity

Mosaic pattern with pulmonary embolism

-Occluded contracted left lower lobe pulmonary artery (arrowhead) , there is decrease in lung attenuation of left lower and right upper lobes and more normally perfused lung contributes to mosaic pattern of lung attenuation (arrows) , incidental note is made of centrilobular emphysema