ChestAirway Diseases

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

Airway Diseasesa) Tracheal Diseases b) Chronic bronchial Diseasesc) Upper Airway Obstruction in Children

a) Tracheal Diseases :1-Neoplastic Diseases2-Non-Neoplastic Diseases

1-Neoplastic Diseases :a) Benignb) Malignant

a) Benign :1-Incidence2-Types

1-Incidence :-Only 10% of tracheobronchial tumors are

benign-Benign tumors are typically < 2 cm

2-Types :a) Papilloma :-Common laryngeal tumors in childrenb) Hamartoma :-Fat density is diagnostic-Often calcified (popcorn pattern)c) Lipoma :-Rounded homogeneous fat attenuation lesion-90 % in males d) Adenoma :-Rare

Papilloma

Small and well-defined posterolateral lesion projecting into tracheal lumen , Papilloma

Hamartoma

Lipoma

CT+C (a) shows a low-attenuation (-5 HU) endobronchial nodule (black arrow) in the bronchus intermedius , post-obstructive atelectasis of the right lower lobe can be seen (white arrow) , CT (b) obtained at the level of the left brachiocephalic vein shows a low attenuation (-95 HU) nodule in the trachea

b) Malignant :1-Incidence2-Types

1-Incidence :-90 % of all tracheobronchial tumors are

malignant

2-Types :a) Primary :-SCC (most common)-Adenoid cystic carcinoma (2nd common)-Mucoepidermoid-Carcinoid

Chest X-ray showing lobulated lesion at the level of the carina (red arrow)

CT+C shows nearly complete central tracheal obstruction with the tumor

Rounded mass at the level of carina causing significant reduction of the lumen of both bronchi , Squamous cell carcinoma

CT shows the tracheal mass extending and obliterating the right main bronchus

CXR (a) shows an upper right paratracheal opacity narrowing the tracheal lumen (arrow) , CT+C (b) confirms the eccentric lobulated soft tissue mass that origins from the right anterolateral tracheal wall and narrows the lumen of the upper trachea , coronal MPR image at mediastinal window setting (c) better depicts the entire extent of the lesion

Mediastinal mass arising from the posterolateral wall of the trachea (a characteristic feature) with invasion of mediastinal fat and esophagus , Cystic adenoid carcinoma

Adenoid Cystic Carcinoma

CT (a) shows an irregular thickening of the left tracheal wall with a lobulated mass protruding into the tracheal lumen (arrow) , CT (b) shows irregular thickening of the left posterolateral tracheal wall with nodular intraluminal extension of tumor (arrow)

Carcinoid

b) Mets :1-Local Extension (common) :-Thyroid cancer-Esophageal cancer-Lung cancer2-Hematogeneous Mets (rare) :-MelanomaBreast cancer

Direct extension to the tracheal lumen of anaplastic thyroid cancer

CT shows a large proximal esophageal mass with asymmetric impression on the posterior tracheal wall suggestive of invasion

Irregular right lateral wall of the trachea secondary to direct extension from small cell carcinoma of the lung 

Tracheal and bronchial metastases from melanoma 

2-Non-Neoplastic Diseases :1-Saber Sheath Trachea2-Tracheopathia Osteoplastica (TPO)3-Tracheobronchomalacia4-Tracheobronchomegaly5-Relapsing Polychondritis6-Post-intubation Tracheal Stenosis

7-Post-infectious Tracheal Stenosis & T.B.8-Tracheobronchial Diverticula9-Bronchial Anthracofibrosis10-Amyliodosis11-Wegner’s Granulomatosis12-Tracheal / Bronchial Narrowing ,

Stenosis or Occlusion

1-Saber Sheath Trachea :a) Pathologyb) Radiographic Features

a) Pathology :-Refers to diffuse coronal narrowing of the

intrathoracic portion of the trachea with concomitant widening of the sagittal diameter , extrathoracic segment of the trachea is always preserved

-It is pathognomonic for COPD-More common in males

b) Radiographic Features :-Marked decrease in the coronal diameter of

the intrathoracic trachea associated with an increase in its sagittal diameter

-Tracheal ring calcification is common

Saber-sheath trachea , notice sparing of extrathoracic trachea and coronal narrowing of the intrathoracic segment

2-Tracheopathia Osteoplastica (TPO) :a) Pathologyb) Radiographic Features

a) Pathology :-Foci of cartilage and bone develop in the

submucosa of the tracheobronchial tree-Benign , rare condition-Only affects the anterior and lateral walls

with sparing of the posterior membranous portion

b) Radiographic Features :-Calcified tracheobronchial tree , nodules ,

osteocartilaginous growth-Thickening of tracheal cartilage-Narrowed lumen-Distal three fourths of the trachea and the

proximal bronchi are most commonly involved

Diffuse stricture of the tracheal lumen due to an irregular thickening of the lateral walls

3-Tracheobronchomalacia :a) Pathologyb) Radiographic Features

a) Pathology :-Refers to weakening of tracheal and bronchial walls -May be primary or secondary :1-Primary (uncommon) :-Occurs in children-May be associated with laryngomalacia2-Secondary (more common) :-Ageing-Prolonged intubation , especially in those with tracheostomy-COPD-Chronic or recurrent infection

b) Radiographic Features :-Collapsed walls of trachea and bronchi-Inspiratory only CT is unable to make the

diagnosis-Diagnosis usually requires airway assessment

after a forced expiration (Dynamic Expiration)-A hallmark of TM is the frown sign, a crescent

bowing of the posterior membranous tracheal wall at expiratory CT scans

On inspiration On expiration

Axial inspiratory CT (a,b) show a normal shape of the tracheal and bronchial lumen , Expiratory CT (c,d) show a severe collapse of the airways with an inward bowing of the posterior wall (frown sign) , mild air-trapping is also evident in both lungs

Tracheomalacia in COPD patient , notice collapse of more than 50% of the tracheal lumen in expiratory image on the right

Significant collapse on expiratory images (below) of trachea and main bronchi , Tracheobronchomalacia 

Significant collapse on expiratory images (below) of trachea and main bronchi

4-Tracheobronchomegaly :a) Pathologyb) Radiographic Features

a) Pathology :-Also known as Mounier-Kuhn syndrome-Rare condition characterized by markedly

dilated airways leading to recurrent infections

-It appears in young patients (third and fourth decade) 

b) Radiographic Features :-Tracheobronchomegaly is diagnosed when

the tracheal diameter is bigger than 3 cm

Markedly enlarged trachea and main bronchi in asymptomatic man

CT shows severe dilatation of the trachea (a) and the right main stem bronchus (b) associated with fibrotic consolidations and traction bronchiectasis in the upper lobes , more evident on the right (a)

5-Relapsing Polychondritis :a) Pathologyb) Radiographic Features

a) Pathology :-Recurrent inflammation of cartilaginous

structures including tracheal cartilages-The etiology is unknown but it is likely

immune-mediated-Tracheal involvement is present in half of

patients with a slightly higher prevalence in women

b) Radiographic Features :-Wall thickening with increased attenuation that

may range from a subtle increase to clear calcifications

-A key fact for diagnosis is the preservation of the posterior wall of the trachea formed by muscular and fibrous tissue and lacking cartilaginous rings , this particular appearance allows diagnosis with a high degree of confidence

Tracheal wall thickening with calcifications involving anterior and lateral walls with preservation of the posterior wall. Notice moderate and diffuse stenosis of the tracheal lumen on the MIP image

Axial CT show smooth tracheal (a) and bronchial (b) wall thickening with calcifications , the typical sparing of the posterior membranous walls of the airways can be seen (arrows) 

6-Post-intubation Tracheal Stenosis :-The placement of endoluminal tubes in the

large airways may cause a reparative fibrotic process at the cuff site (in tracheal intubation) or at the stoma site (in tracheostomy) leading to a tracheal narrowing

CT (a) shows an eccentric stenosis of the subglottic tracheal lumen on the right (arrow) , external VR image (b) along the long axis of the trachea better depicts the stricture extent and the typical appearance of “hourglass” of the trachea

7-Post-infectious Tracheal Stenosis & T.B. :-Central airways may be involved in 10-40% of

cases of pulmonary parenchymal tuberculosis by lymphatic spread or local invasion from mediastinal affected lymph nodes

-The most frequent site of stenosis is the lower third of the trachea and the main stem bronchi

CT (a,b) show enlarged lymph nodes (arrows) in the right paratracheal region and subcarinal region that infiltrate distal trachea and right main bronchus walls determining airway lumen narrowing , coronal CT reformation (c) and VR image (d) better illustrate the extension of the lesions throughout the tracheobronchial tree

8-Tracheobronchial Diverticula :-May be congenital or acquired-Congenital usually very small with a very

narrow communication with the airway , whereas the acquired is bigger and usually have a wide communication with the airway

Congenital diverticulum , Axial CT (a) show an air-filled right paratracheal cyst (arrow) at the cervico-thoracic junction , coronal MPR (b) better depicts the apparent communication (arrow) with the tracheal lumen by a narrow neck.

Acquired diverticulum , Axial CT (a) and oblique MPR image (b) show a large air-filled paratracheal cyst (arrow) at the cervico-thoracic junction , the large dimension and the broad base are consistent with an acquired diverticulum

Right paratracheal diverticulum , notice narrow connection between diverticulum and tracheal lumen

9-Bronchial Anthracofibrosis :-Benign condition affecting more

frequently elderly women-The term refers to the bronchoscopic

finding of dark anthracotic pigments in the bronchial wall with subsequent bronchial narrowing or obliteration in patients without a relevant history of pneumoconiosis or smoking

-The most commonly reported finding on CT scans is lobar or segmental post-obstructive atelectasis , multifocal stenoses of lobar and segmental bronchi with peribronchial soft tissue thickening and calcified or noncalcified lymph nodes may also be seen

CT+C (a) shows partial atelectasis of right upper lobe with smooth narrowing of right main bronchus and obstruction of right upper lobe bronchus , an enlarged lymph node (arrow) adjacent to involved bronchus can be seen , axial non-enhanced CT (b) shows obstructed right middle lobe bronchus resulting in partial atelectasis of right middle lobe , calcified lymph nodes adjacent to right middle lobe bronchus are also present (black arrows) , lingular segmental bronchus is thickened with adjacent enlarged lymph nodes containing calcification (white arrow)

10-Amyliodosis :-Diffuse involvement of the tracheobronchial

tree beginning from the trachea and large bronchi extending sometimes to segmental bronchi

-CT shows multifocal , nodular or circumferential wall thickening of soft-tissue density with a smooth surface and possible concentric calcifications

Axial CT (a,c) show diffuse circumferential and smooth wall thickening with mild calcifications of the trachea , main stem bronchi and lobar bronchi bilaterally , axial CT (b) shows an almost complete occlusion of the right upper lobar bronchus with a distal chronic post-obstructive atelectasis of the anterior segment of the right upper lobe (arrow)

Circumferential thickening of the tracheal wall with irregular appearance in virtual bronchoscopy image

11-Wegner’s Granulomatosis :-Late complication of the disease-CT shows focal or more often diffuse

circumferential wall thickening

Smooth subglotic wall thickening , Wegener granulomatosis

Asymmetric thickening of the tracheal wall progressing to significant lumen stenosis of subglotic position , Wegener granulomatois

12-Tracheal / Bronchial Narrowing , Stenosis or Occlusion :

a) In the Lumenb) In the Wallc) Outside the Wall

a) In the Lumen :1-Foreign body2-Mucus plug3-Misplaced endotracheal tube4-Broncholithiasis

b) In the Wall :-See Before + Bronchial Atresia

c) Outside the Wall :1-Lymph nodes2-Mediastinal tumors 3-Enlarged left atrium4-Aortic aneurysm5-Anomalous origin of left pulmonary artery from right

pulmonary artery :-Producing compression of the right main bronchus as it

passes over it between the trachea and esophagus to reach the left hilum

-PA CXR shows the right side of the trachea to be indented and the vessel is seen end-on between the trachea and esophagus on the lateral view

Aberrant left pulmonary artery , aberrant artery extends between trachea & esophagus indenting both (arrows)

b) Chronic Bronchial Diseases :1-COPD2-Emphysema3-Bronchial Asthma4-Bronchiectasis5-Cystic Fibrosis6-Bronchiolitis Obliterans

1-COPD :a) Pathologyb) Clinical Picturec) Radiographic Features

a) Pathology :-Represents a spectrum of obstructive airway diseases-It includes two key components which are chronic

bronchitis and emphysema-In contrast to asthma , the histologic changes of COPD

are irreversible and gradually progress over time-In chronic bronchitis , there is diffuse hyperplasia of

mucous glands with associated hypersecretion and bronchial wall inflammation

-Emphysema involves the destruction of alveolar septa and pulmonary capillaries leading to decreased elastic recoil and resultant air trapping

b) Clinical Picture : More in smokers1-Blue Bloaters : Bronchitis-Bronchitis , tussive type of COPD-Episodic dyspnea due to exacerbation of bronchitis-Young patients-Cyanosis2-Pink Puffers : Emphysema-Emphysematous type of COPD-Progressive exertional dyspnea due to the emphysema-Elderly patients

c) Radiographic Features :1-Plain Radiography2-CT

1-Plain Radiography :-Findings of chronic bronchitis are

nonspecific and include increased bronchovascular markings (dirty lung sign) and cardiomegaly

CXR shows increased bronchovascular markings

Dirty Lung sign

-Emphysema manifests as lung hyperinflation with flattened hemidiaphragms , a small heart and possible bullous changes , on the lateral radiograph, a "barrel chest" with widened AP diameter may be visualized , the "saber-sheath trachea" sign refers to marked coronal narrowing of the intrathoracic trachea (frontal view) with concomitant sagittal widening (lateral view)

CXR shows the signs of hyperinflation of the lungs (flattening of hemidiaphragms , widening of retrosternal and retrocardiac spaces green and yellow stars respectively) and loss of regular vascular branching pattern

Bullous changes

Saber sheath trachea

2-CT :-In chronic bronchitis , bronchial wall

thickening and increased lung markings (dirty lung appearance) may be seen , repeated inflammation can lead to scarring with bronchovascular irregularity and fibrosis

CT shows bronchial wall thickening

CT in patient with chronic bronchitis showing thickening of the bronchial walls (red arrows) and mucous within the bronchi (yellow arrows)

-Emphysema is diagnosed by alveolar septal destruction and airspace enlargement which may occur in a variety of distributions

-Centrilobular emphysema is predominantly seen in the upper lobes

-Panlobular emphysema predominating in the lower lobes-Paraseptal emphysema tends to occur near lung

fissures and pleura-Formation of giant bullae may lead to compression

of mediastinal structures while rupture of pleural blebs may produce spontaneous pneumothorax / pneumomediastinum

Centrilobular Emphysema

Panlobular Emphysema

Paraseptal Emphysema

Bullous Emphysema

CT shows a focal area of emphysema (yellow arrow) , pneumothorax (red arrow)

2-Emphysema :a) Pathologyb) Clinical Picturec) Radiographic Featuresd) Differential Diagnosis

a) Pathology :-Abnormal enlargement of distal airspaces with destruction

of alveolar walls with or without fibrosis-More in smokers-There are three morphologic sub types of emphysema

which are named according to their relationship to the secondary pulmonary lobule :

1-Centrilobular Emphysema :-Is the most frequently encountered type and affects the

proximal respiratory bronchioles-More in the upper zones-It is strongly associated with smoking 

2-Panlobular Emphysema :-Affects the entire secondary pulmonary lobule ,

more in the lower zones-Seen particularly in alpha-1-antitrypsin (AAT)

deficiency (exacerbated by smoking) 3-Paraseptal Emphysema :-Affects the peripheral parts of the secondary

pulmonary lobule near lung fissures and pleura-It is also associated with smoking and can lead to

the formation of subpleural bullae and spontaneous pneumothorax 

Centrilobular Panlobular Paraseptal

Centrilobular Panlobular Paraseptal

b) Clinical Picture :-The clinical features of emphysema should be

distinguished from the signs and symptoms of chronic bronchitis

-Patients with emphysema often referred to as pink puffers

-Patients with chronic bronchitis often referred to as blue blotters

-However in clinical practice features of these two syndromes coexist as chronic obstructive pulmonary disease

c) Radiographic Features :1-Plain Radiography2-CT

1-Plain Radiography :a) Hyperinflation :-Flattened hemidiaphragm(s) : most reliable sign , highest

level of the dome is <1.5 cm above a straight line drawn between the costophrenic and the vertebrophrenic junctions

-Increased and usually irregular radiolucency of the lungs-Increased retrosternal airspace-Increased AP diameter of chest-Widely spaced ribs-Sternal bowing-Tenting of the diaphragm-Saber sheath trachea

Normal Diaphragm Flattened Diaphragm

Normal Flattening of the diaphragm

Increased radiolucency , increased AP diameter of chest

Normal retrosternal space Increased

Normal Widely spaced ribs

b) Vascular changes :-Decreased number of vessels in areas of

abnormal lung-Absence of peripheral pulmonary vessels-Fewer arterial branches-Central pulmonary artery increased in size

Hyperlucency of the lungs with fewer vascular markings and prominence of the pulmonary arteries (arrows)

2-CT : In all three sub types, the emphysematous spaces are not bounded by any visible wall

a) Centrilobular Emphysema :-It is predominantly located in the upper zones of

each lobe (i.e. apical and posterior segments of the upper lobes and superior segment of the lower lobes) has a patchy distribution

-It appears as focal lucencies  (emphysematous spaces) which measure up to 1cm in diameter located centrally within the secondary pulmonary lobule often with a central or peripheral dot representing the central bronchovascular bundle

b) Panlobular Emphysema :-Predominantly located in the lower lobes ,

has a uniform distribution across parts of the secondary pulmonary lobule which are homogeneously reduced in attenuation

c) Paraseptal Emphysema :-Located adjacent to the pleura and septal lines

with a peripheral distribution within the secondary pulmonary lobule , the affected lobules are almost always sub-pleural and demonstrate small focal lucencies up to 10mm in size

-Any larger than 10mm and they should be referred to as subpleural blebs or subpleural bullae

Bullous Emphysema

Emphysema with pneumothorax

Emphysema with superimposed infection

d) Differential Diagnosis :-Cystic lung disease , all have visible walls1-Lymphangiomyomatosis (LAM)2-Pulmonary Langerhans cell histiocytosis

(LCH)3-Honeycomb lung : usually reduced lung

volumes

3-Bronchial Asthma :a) Pathologyb) Radiographic Features

a) Pathology :-Hyperirritability of airways causes reversible

airway obstruction (bronchial smooth muscle contraction , mucosal edema , hypersecretion of bronchial secretory cells : bronchospasm)

-The etiology is unknown (IgE participation)

b) Radiographic Features :1-Plain Radiography2-CT

1-Plain Radiography :-Plain films can be normal in upto 75% of

patients with asthma-Severe or chronic asthma :Air trapping , hyperinflation : flattened

diaphragm , increased retrosternal airspace

Gloved finger sign , finger like projections from hilum from bronchial mucoid impaction in allergic bronchopulmonary aspergillosis or asthma

2-CT :-CT is usually used to detect the presence of

complicated associated conditions such as allergic bronchopulmonary aspergillosis and not to directly diagnose asthma

-Bronchial wall thickening , tramlines (also seen in chronic bronchitis , cystic fibrosis , bronchiectasis & pulmonary edema)

Mild bronchial thickening and dilatation

Central bronchiectasis , a hallmark of allergic bronchopulmonary aspergillosis (right arrow) and the peripheral tree-in-bud appearance of centrilobular opacities (left arrow) which represent mucoid impaction of the small bronchioles

4-Bronchiectasis :a) Pathologyb) Clinical Picturec) Radiographic Featuresd) Differential Diagnosis

a) Pathology :-Refers to irreversible abnormal dilatation of the

bronchial tree-Types :1-Cylindrical bronchiectasis :-Bronchi have a uniform caliber , do not taper and

have parallel walls (tram track sign when viewed in a sagittal section and signet ring sign when viewed in a coronal section)

-Commonest form 

2-Varicose bronchiectasis :-Beaded appearances where dilated bronchi have

interspersed sites of relative narrowing-Uncommon3-Cystic bronchiectasis : More in lower lobes-Severe form with cyst-like bronchi that extend to the

pleural surface , air-fluid levels are commonly present4-Traction bronchiectasis :-Bronchiectasis which result from the traction of fibrotic lung

surrounding an airway

Cylindrical bronchiectasis

Cylindrical Bronchiectasis

Varicose bronchiectasis

Cystic bronchiectasis

Cystic bronchiectasis

Traction bronchiectasis

b) Clinical Picture :-Bronchiectasis typically presents with

recurrent chest infections , production of copious amounts of sputum and hemoptysis

-Hemoptysis is often the only symptom and is encountered in up to 50% of case

c) Radiographic Features :1-Plain Radiography2-CT

1-Plain Radiography :-Tram-track opacities (horizontal , parallel lines

corresponding to thickened , dilated bronchi) are seen in cylindrical bronchiectasis

-Air-fluid levels may be seen in cystic bronchiectasis

-Bronchial wall thickening (best seen end-on)-Increase in bronchovascular markings

Thin-walled, cystic structures in right lower lobe (white arrow) , some with air-fluid levels (yellow arrows)

CXR (a) shows thickening of the bronchial walls and “tramlines” in the middle and lower regions of the lungs suggestive of bronchiectasis, confirmed on CT (b,c)

2-CT :a) Increased bronchoarterial ratio :-Bronchi appear larger than accompanying vesselsb) Bronchial wall :-Thickened wall (normally wall of bronchus should

be less than half the width of the accompanying pulmonary artery branch)

-Signet ring sign , focally thickened bronchial wall adjacent to pulmonary artery branch

-Tram track sign , tube like parallel lines representing thickened bronchial walls

Signet ring

Tram Track sign

Cystic bronchiectasis with air fluid level

d) Differential Diagnosis :Conditions that may mimic cystic bronchiectasis include :1-Langerhans cell histiocytosis (LCH)2-Lymphangiomyomatosis (LAM)3-Lymphocytic interstitial pneumonitis (LIP)4-Pulmonary manifestations of AIDS5-Pneumocystis pneumonia (PCP)6-Emphysema (To distinguish emphysema from

bronchiectasis, expiratory scans will show air trapping in bullae while cystic bronchiectasis will collapse)

7-Cystic pulmonary metastases

5-Cystic Fibrosis :a) Pathologyb) Clinical Picturec) Locationd) Radiographic Featurese) Differential Diagnosis

a) Pathology :-Caused by an abnormality in the cystic fibrosis

transmembrane conductance regulator protein (CFTR) which regulates the passage of ions through membranes of mucus-producing cells

-Dysfunction of exocrine glands causing thick tenacious mucus that accumulates and causes bronchitis and pneumonia

-Reduced mucociliary transport : airway obstruction with massive mucus plugging

b) Clinical Picture :1-Pulmonary, 100% :-Chronic cough-Recurrent pulmonary infections : colonization of plugged airways by

Staphylococcus and Pseudomonas-Progressive respiratory failure-Finger clubbing : hypertrophic osteoarthropathy from hypoxemia2-GI tract :-Pancreatic insufficiency , 85% : steatorrhea , malabsorption-Liver cirrhosis-Rectal prolapse-Neonates : meconium ileus, meconium peritonitis, intussusception3-Other :-Sinusitis : hypoplastic frontal sinus, opacification of other sinuses-Infertility in males

c) Location :-Predominantly upper lobes , superior

segments of lower lobes and central (perihilar) distribution

d) Radiographic Features :1-Plain Radiography2-CT

1-Plain Radiography :-Chest x-rays are insensitive to the early changes of cystic

fibrosis, with changes seen on HRCT in 65% of patients with CF and normal CXR

-Later changes include :1-Bronchiectasis2-Hyperinflation3-Lobar collapse4-Pulmonary arterial enlargement due to pulmonary arterial

hypertension is seen in patients with long standing disease

CXR shows diffuse interstitial disease with bronchiectasis and nodular densities of mucoid impaction

CXR shows hyperinflation and predominantly upper lobe bronchiectasis

2-CT :a) Bronchiectasis :*Progresses with time from cylindrical to varicose to cystic*Severity :-Mild: lumen equal to adjacent blood vessels-Moderate: lumen 2 to 3 times the size of adjacent blood

vessels-Severe : lumen >3 times the size of adjacent blood vessels*Peribronchial wall thickening , wall thickness > the

diameter of adjacent blood vessels

b) Mosaic attenuation pattern :-Due to air trapping-Best seen on expiratory scansc) Mucus plugging within bronchi :-Finger in glove appearance

e) Differential Diagnosis :1-Allergic bronchopulmonary aspergillosis (ABPA) 2-Tracheobronchomegaly (Mounier-Kuhn

syndrome)3-Williams-Campbell syndrome4-Langerhans cell histiocytosis (LCH)5-Lymphangiomyomatosis (LAM)6-Congenital cystic bronchiectasis

6-Bronchiolitis :a) Pathologyb) Radiographic Featuresc) Swyer-James syndrome

a) Pathology :-Inflammatory and fibrotic types :a) Inflammatory Bronchiolitis :1-Infectious :-Acute or chronic infection (viral ,

mycoplasma & mycobacterial)2- Hypersensitivity Penumonitis :-Organic or inorganic inhaled agents

3-Respiratory Bronchiolitis :-Cigarette smoking4-Follicular and Lymphocytic :-Sjögren's syndrome , rheumatoid arthritis &

immunodeficiency5-Panbronchiolitis :-Idiopathic6-Bronchiectasis :-Cystic fibrosis & previous infection

b) Fibrotic (Constrictive) Bronchiolitis :-Postinfectious , toxic fumes ,

transplantation , cryptogenic , collagen vascular diseases & drugs

b) Radiographic Features :1-Plain Radiography2-CT

1-Plain Radiography :-Can be normal or non specific , some

associated features include :a) Hyperinflationb) Attenuation of vascular markingsc) Occasionally : reticular or reticulo-nodular

markings

Lung hyperinflation with a flattened diaphragm and bilateral atelectasis in the right apical and left basal regions in a 16-day-old infant with severe bronchiolitis

Nonspecific hyperinflation with flattening of the hemidiaphragms on lateral CXR , as well as increased AP diameter and prominent size of retrosternal clear space , mild bilateral symmetric perihilar peribronchial prominence

2-CT :a) Direct Signs :-Thickening of the bronchiolar wall by inflammatory cells

results in centrilobular nodules and V- or Y-shaped branching linear opacities that represent the tree-in-bud pattern

-Inflammatory cellular infiltration in the peribronchiolar alveoli results in poorly defined centrilobular nodules that often have an attenuation less than that of soft tissue

-Bronchiolectasis is a less common direct sign of bronchiolitis and is found most commonly in chronic forms of bronchiolitis , the dilated bronchioles are identifiable close to the pleural surface 

Multiple poorly defined centrilobular nodules, many of which connect to branching linear structures (arrows) , tree-in-bud pattern

Diffuse fine poorly defined centrilobular nodules (arrows) with more patchy ground-glass opacity posteriorly

Centrilobular nodules with tree-in-bud pattern (arrowheads), bronchiolectasis (arrow), and cylindric bronchiectasis

b) Indirect Signs :-Air trapping is an indirect sign of obstructive

small airways disease and may be identified by the presence of mosaic attenuation on inspiratory CT that is accentuated with expiratory imaging

Multiple patchy areas of low attenuation in both lungs , note mild bronchial wall thickening and cylindric bronchiectasis

Expiratory high-resolution CT image shows accentuation of areas of decreased attenuation , confirming presence of air trapping

c) Swyer-James Syndrome (Mcleod) :1-Pathology2-Radiographic Features

1-Pathology :-The late sequela of bronchiolitis in

childhood-Is a rare lung condition that manifests

as unilateral hemithorax lucency as a result of post-infectious obliterative bronchiolitis

-The condition typically follows a viral respiratory infection (adenovirus) in infancy or childhood

2-Radiographic Features :a) Plain Radiographyb) CT

a) Plain Radiography :-It is generally characterized on radiographs

by a unilateral small lung with hyperlucency and air trapping

b) CT :-CT shows the affected lung as being

hyperlucent with diminished vascularity , the size of the majority of the affected lobes are smaller although occasionally they can be normal

- Bronchiectasis may be present although this is not a universal finding

c) Upper Airway Obstruction in Children :(i) Approach(ii) Causes of Upper Airway Obstruction

(i) Approach :-Inspiratory stridor is the most common

indication for radiographic upper airway evaluation

-Obtain 3 films :*Lateral neck : full inspiration , neck

extended*AP & lateral chest : full inspiration , include

upper airway

-Primary diagnostic considerations : a) Congenital abnormalities (webs , malacia)b) Infection (epiglottitis , croup , abscess)c) Foreign body (airway or

pharyngoesophageal)d) Masses (lymphadenopathy , neoplasms)

-If upper airway is normal , consider : 1-Pulmonary causes (foreign body ,

bronchiolitis)2-Mediastinal causes (vascular rings ,

slings)3-Congenital heart disease (CHD)

-Normal Appearance :*Three anatomic regions : 1-Supraglottic region2-Glottic region : ventricle and true cords3-Subglottic region*Epiglottis and aryepiglottic folds are thin structures*Glottic shoulders are seen on AP view*Adenoids are visible at 3 to 6 months after birth*Normal retropharyngeal soft tissue thickness (C1-

C4) = three-fourths vertebral body width

(ii) Causes of Upper Airway Obstruction :a) Congenital Abnormalities (webs ,

malacia)b) Infection (epiglottitis , croup , abscess)c) Foreign Body (airway or

pharyngoesophageal)d) Masses (lymphadenopathy , neoplasms)

a) Congenital Abnormalities :1-Laryngomalacia2-Tracheomalacia3-Webs4-Tracheal Stenosis5-Subglottic Stenosis6-Choanal Atresia

1-Laryngomalacia :-Common cause of stridor in the 1st year of

life and usually resolves by 2 years -Immature laryngeal cartilage leads to

supraglottic collapse during inspiration-Diagnosis is established by fluoroscopy

(laryngeal collapse with inspiration)

2-Tracheomalacia :-Weakness of tracheal wall which may be primary or

secondary :a) Primary :-Premature infants -Cartilage disorders (polychondritis , chondromalacia &

MPS)b) Secondary :-Following prolonged intubation-With TOF / osophageal atresia-With vascular ring or other extrinsic vascular compression-With long standing external compression by tumor

3-Webs :-Most common in larynx

4-Tracheal Stenosis :-Diffuse hypoplasia , 30%-Focal ringlike stenosis , 50%-Funnel-like stenosis , 20%

5-Subglottic Stenosis :-Fixed narrowing at level of cricoid-Failure of laryngeal recanalization in utero

6-Choanal Atresia :-Most common congenital nasal abnormality-Bilateral in 33 % or unilateral (R>L)-Bony (90 %) or membranous , complete or incomplete-Diagnosis is done by failure to pass a catheter through the

nose

b) Infection :1-Epiglottitis2-Croup3-Retropharyngeal Abscess4-Edema5-Retropharyngeal Hemorrhage

1-Epiglottitis :a) Incidenceb) Clinical Picturec) Radiographic Featuresd) Differential Diagnosis

a) Incidence :-Life threatening bacterial infection of the

upper airway-Most commonly caused by Haemophilus

influenzae-Age : 3 to 6 years

b) Clinical Picture :-Fever-Dysphagia-Drooling-Sore throat

c) Radiographic Features :-Key radiographic view : lateral neck-Thickened epiglottis-Thickened aryepiglottic folds (hallmark)-Subglottic narrowing due to edema , 25% :

indistinguishable from croup on AP view-Distention of hypopharynx

d) Differential Diagnosis :-Other causes of enlarged epiglottis or

aryepiglottic folds : 1-Caustic ingestion2-Hereditary angioneurotic edema3-Omega-shaped epiglottis (normal variant

with normal aryepiglottic folds)4-Stevens-Johnson syndrome

2-Croup :a) Incidenceb) Clinical Picturec) Radiographic Features

a) Incidence :-Age : 6 months to 3 years (younger age

group than epiglottitis)-Most commonly caused by parainfluenza

virus-Subglottic laryngotracheobronchitis

b) Clinical Picture :-Barking cough-Upper respiratory tract infection-Self limited

c) Radiographic Features :-Key view : AP view-Subglottic narrowing (inverted “V” or

“steeple sign”)-Steeple sign : loss of subglottic shoulders-Lateral view should be obtained to exclude

epiglottitis

3-Retropharyngeal Abscess :a) Incidenceb) Clinical Picturec) Radiographic Featuresd) Differential Diagnosis

a) Incidence :-Typically due to extension of a suppurative

bacterial lymphadenitis , most commonly S. aureus , group B streptococci , oral flora

-Age : <1 year-Other causes include foreign body

perforation and trauma

b) Clinical Picture :-Fever-Stiff neck-Dysphagia-Stridor (uncommon)-Most cases present as cellulitis rather than

true abscess

c) Radiographic Features :-Widened retropharyngeal space (most

common finding)-Air in soft tissues is specific for abscess-May contain air fluid level-Straightened cervical lordosis-CT : rim enhancement

d) Differential Diagnosis :-Retropharyngeal hematoma-Neoplasm (i.e. rhabdomyosarcoma)-Lymphadenopathy

4-Edema : (Laryngeal)-Caused by :a) Angioedema (allergic , anaphylactic or

hereditary)b) Inhalation of noxious gasesc) Trauma

5-Retropharyngeal Hemorrhage :-Due to :1-Trauma2-Neck surgery3-Direct carotid arteriography4-Bleeding disorders-Widening of the retropharyngeal soft tissue

space

c) Foreign Body :1-Incidence2-Location3-Radiographic Features

1-Incidence :-Common cause of respiratory distress-Age : 6 months to 4 years

2-Location :-right bronchi > left bronchi > larynx ,

trachea

3-Radiographic Features :a) Bronchial foreign body :-Unilateral air trapping causing hyperlucent

lung , 90%-Only 10% of foreign bodies are radiopaque-Expiratory film or lateral decubitus makes

air trapping more apparent

b) Tracheal foreign body :-CXR is usually normal-Foreign body usually lodges in sagittal

plane

d) Masses :1-Grossly Enlarged Tonsils & Adenoids2-Nasal Angiofibroma3-Antrochoanal Polyp4-Subglottic Hemangioma5-Respiratory Paplillomatosis6-External Compression

1-Grossly Enlarged Tonsils & Adenoids :a) Incidenceb) Radiographic Features

a) Incidence :-The tonsils consist of lymphoid tissue that

encircles the pharynx-Three groups : pharyngeal tonsil (adenoids) ,

palatine tonsil and lingual tonsil-Tonsils enlarge secondary to infection and may

obstruct nasopharynx and/or eustachian tubes-Rarely , bacterial pharyngitis can lead to a

tonsillar abscess (quinsy abscess), which requires drainage

-Specific causes include :1-Mononucleosis (Epstein-Barr virus)2-Coxsackievirus (herpangina , hand-foot-

mouth disease)3-Adenovirus (pharyngoconjunctival fever)4-Measles prodrome (rubeola)5-β-Hemolytic Streptococcus (quinsy

abscess)

b) Radiographic Features :-Mass in posterior nasopharynx (enlarged

adenoids)-Mass near end of uvula (palatine tonsils)-CT is useful to determine the presence of a

tonsillar abscess

2-Nasal Angiofibroma

3-Antrochoanal Polyp

4-Subglottic Hemangioma :-The most common subglottic soft tissue mass in

infancy-Occurs before 6 months of age-Produces asymmetrical narrowing of the

subglottic airway

5-Respiratory Paplillomatosis :-Occur anywhere from the nose to the lungs-Irregular soft tissue masses which may

cavitate around the glottis or in the trachea

6-External Compression :-From Other Mediastinal Structures

(lymphadenopathy)