1. Radiographics. 2003;24:e17 Presented by Int. 吳建霆 Dec. 20th, 2005
Congenital Anomalies of the Tracheobronchial Tree, Lung, and Mediastinum
Radiographics. 2003;24:e17
Presented by Int. 吳建霆
Dec. 20th, 2005

2. Outline Tracheobronchial Anomalies Anomalies of the Lung
Tracheomalacia
Tracheal Stenosis
Tracheal Bronchus
Bronchial Atresia
Bronchogenic Cyst
Anomalies of the Lung
Pulmonary Underdevelopment
Scimitar Syndrome
Congenital Cystic Adenomatoid Malformation
Congenital Lobar Emphysema
Pulmonary Sequestration
Esophageal Anomalies
Esophageal Atresia and Tracheoesophageal Fistula
Esophageal Duplications

3. Tracheobronchial Anomalies
Tracheomalacia
Tracheal Stenosis
Tracheal Bronchus
Bronchial Atresia
Bronchogenic Cyst

4. Tracheomalacia
Defined as tracheal wall softening due to an abnormality of the cartilaginous ring and hypotonia of the myoelastic elements
Primary tracheomalacia
Congenital immaturity of the tracheal cartilage
Secondary tracheomalacia
Previously normal cartilage undergoes degeneration

5. Tracheomalacia Symptoms are similar to those of asthma
wheeze, cough, stridor, dyspnea, tachypnea, cyanosis, and recurrent respiratory tract infections
Associated with other developmental defects such as a vascular ring or tracheoesophageal fistula
Congenital diffuse malacia of the airway improves by age 6~12 months

6. Tracheomalacia Lateral fluoroscopy and esophagography
An exaggerated decrease in the caliber of the trachea during expiration

7. Tracheal Stenosis
Characterized by the presence of focal or diffuse complete tracheal cartilage rings, resulting in a fixed tracheal narrowing
50% focal, 30% generalized, and 20% funnel-shaped
Symptoms are variable
Length of stenosis does not appear to be as critical as degree of stenosis
Focal congenital tracheal stenosis consists of a simple local narrowing of the trachea, usually in the lower third
Symptoms are variable, depending on the age of the child, the degree of stenosis, and the potential presence of associated anomalies
airway resistance is only linearly proportional to length of stenosis, whereas resistance increases fourfold relative to luminal radius decrease

8. Tracheal Stenosis In isolation or in conjunction with other anomalies
The most common is the pulmonary artery sling complex
The left pulmonary artery originates from the right pulmonary artery and encircles the right mainstem bronchus and distal trachea

9. Tracheal Stenosis Frontal and lateral radiographs Combined with
ecause of ionizing radiation, CT should be used only in selected cases
If necessary, helical CT or electron-beam CT can be useful for evaluating dynamic changes in the airway
Magnetic resonance (MR) imaging is valuable for demonstrating the relationship of the airway to adjacent blood vessels without injection of intravascular contrast medium
Frontal and lateral
radiographs
Combined with
barium esophagography

10. Tracheal Bronchus
Described as a variety of bronchial anomalies arising in the trachea or main bronchus and directed toward the upper-lobe territory
Usually exits the right lateral
wall of the trachea less than
2 cm above the major carina
Right tracheal bronchus has a prevalence of 0.1%ﾁV2% and left tracheal bronchus a prevalence of 0.3%ﾁV1% in bronchographic and bronchoscopic studies

11. Tracheal Bronchus Displaced Supernumerary Tracheal diverticula
If the anatomic upper-lobe bronchus is missing a single branch
Supernumerary
If the right upper-lobe bronchus has a normal trifurcation into apical, posterior, and anterior segmental bronchi
Tracheal diverticula
If the supernumerary bronchi end blindly
Apical accessory lungs or tracheal lobes
If they end in aerated or bronchiectatic lung tissue
The displaced type of tracheal bronchus is more frequent than the supernumerary type

12. Tracheal Bronchus Patients are usually asymptomatic
Persistent or recurrent upper-lobe pneumonia, atelectasis or air trapping, and chronic bronchitis
Bronchiectasis, focal emphysema, and cystic lung malformations may coexist

13. Tracheal Bronchus Chest CT
A small area of hypoattenuation arising directly from the trachea

14. Tracheal Bronchus
Bronchography and bronchoscopy allow the direct visualization of the ectopic bronchus

15. Bronchial Atresia
Results from focal obliteration of a proximal segmental or subsegmental bronchus that lacks communication with the central airways
The bronchi distal to the stenosis become filled with mucus and form a bronchocele
The alveoli are ventilated by collateral pathways and show features of air-trapping
The upper-lobe is more frequently affected
May be acquired postnatally owing to traumatic or postinflammatory insult to the bronchus
Most often affects segmental bronchi at or near their origin; however, lobar or subsegmental bronchi may also be involved
The abnormality is an incidental finding in approximately 50% of cases, mostly in young men

16. Bronchial Atresia In the newborn period Later in childhood In adults
Bronchial atresia is seen as a water-density mass
Later in childhood
Bronchial atresia is found because of focal air trapping
In adults
Bronchial atresia is seen as a solitary pulmonary nodule due to a mucus plug
The mass is fetal lung liquid trapped behind the atresia
The short atretic segment leads to accumulation of mucus within the distal bronchi to form a bronchocele, and underventilation of the affected part of the lung occurs

17. Bronchial Atresia CT is a sensitive modality
It shows a round opacity at the site of the atresia, medial to the air trapping
The characteristic chest radiographic finding consists of a bronchocele, seen as rounded, branching opacities radiating from the hilum. The bronchocele may contain an air-fluid level. The distal lung is emphysematous and produces an area of hyperlucency around the affected bronchi. In newborns, the affected segment may be seen as a fluid-filled mass

18. Bronchogenic Cyst Originate from the primitive ventral foregut
Location
Mediastinal: paratracheal (usually right-sided), carinal, or hilar
Intrapulmonary: medial third of the lung, lower lobes
Lower neck
Account for 40%~50% of all congenital mediastinal cysts
There is a slight male predominance
Approximately two-thirds are within the mediastinum, and one-third are intraparenchymal
The carinal location is most frequent

19. Bronchogenic Cyst
The cysts contain mucoid material and are lined by ciliated columnar or cuboidal epithelium
Their walls contain smooth muscle and cartilage
Do not initially communicate with the tracheobronchial tree
Two-thirds of the patients are symptomatic
Caused by compression of the trachea or bronchi
Infection occurs in 20% of patients with intraparenchymal cysts
Instrumentation of the cyst or infection may lead to air-filled cyst or an air-fluid level
However, most bronchogenic cysts in children are found incidentally when imaging is performed for other reasons

20. Bronchogenic Cyst
In infants and children, the chest radiograph is diagnostic
Appear as water-density mass lesions
Show no contrast enhancement

21. Bronchogenic Cyst
Intrapulmonary cysts may show air or an air-fluid level
When they become infected they may show wall enhancement

22. Anomalies of the Lung Pulmonary Underdevelopment Scimitar Syndrome
Congenital Cystic Adenomatoid Malformation
Congenital Lobar Emphysema
Pulmonary Sequestration

23. Pulmonary Underdevelopment
Classified into three groups
Group 1, bronchus and lung are absent (agenesis)
Group 2, a rudimentary bronchus is present and limited to a blind-end pouch without lung tissue (aplasia)
Group 3, there is bronchial hypoplasia with variable reduction of lung tissue (hypoplasia)
The abnormality is usually unilateral
The contralateral lung is normal in structure but has compensatory hypertrophy

24. Pulmonary Agenesis
Ocasionally, the agenesis may be confined to one lobe (left upper lobe)
More than 50% have associated congenital anomalies
Cardiovascular (PDA and patent foramen ovale), gastrointestinal, skeletal, and genitourinary systems
Patients with right-lung agenesis have a shorter life expentancy
The etiology of lung agenesis is unknown, although genetic, teratogenic, and mechanical factors have been proposed as possible causes
there is no side or gender predominance
Most of the limb and spinal anomalies are ipsilateral to the pulmonary agenesis, whereas the rib anomalies are variable
this suggests that the right-lung agenesis has a greater frequency of an associated shift of the heart and mediastinum, with corresponding distortion of bloods vessel and bronchi

25. Pulmonary Agenesis
A small, completely opaque hemithorax with displacement
of the mediastinal structures and diaphragm
CT angiography and MR angiography are currently the
imaging modalities of choice

26. Pulmonary Hypoplasia
Caused by factors compromising the thoracic space available for lung growth
Extrathoracic causes: oligohydramnios
Intrathoracic causes: congenital diaphragmatic hernia
Extralobar sequestration: agenesis of the diaphragm, large pleural effusion
Other causes: decreased pulmonary vascular perfusion (tetralogy of Fallot, unilateral absence of the pulmonary artery)
(Potter syndrome: renal agenesis, abnormal fasciae, limb anomalies, and bilateral pulmonary hypoplasia)
Jeune syndrome (asphyxiating thoracic dystrophy)

27. Pulmonary Hypoplasia
In cases of premature rupture of membranes at 15~28 weeks gestation, the reported prevalence of pulmonary hypoplasia ranges from 9% to 28%
Manifestation
Early respiratory distress after birth, cyanosis, tachypnea, hypoxia, hypercapnea, and acidosis
Pneumothorax and pulmonary hypertension are common serious complications
Pneumothorax often develops spontaneously or secondary to mechanical ventilation

28. Pulmonary Hypoplasia Plain radiographs
Decreased aeration of the affected hemithorax (more frequent in the right lung) and a small thoracic cage
Displacement of the mediastinum to the side of the hypoplasia
In some cases, a cystic appearance is encountered, which could be due to a developmental defect at the bronchioloalveolar junction (congenital bronchiectasis)

29. Scimitar Syndrome
Also called venolobar syndrome and hypogenetic lung syndrome
Anomalous systemic arterial supply to the lower lobe of the right lung from the subdiaphragmatic aorta or its main branches
Ipsilateral anomalous pulmonary drainage of part or all of the right lung into the inferior vena cava
Hypoplasia or other malformation of the right pulmonary artery
Dextrorotation of the heart
Hypoplasia of the right lung
is a congenital cardiovascular anomaly involving the right lung

30. Scimitar Syndrome Three forms
The infantile form: a large shunt between the abnormal artery that supplies the lower lobe of the right lung and the subdiaphragmatic aorta
In the adult form: a small shunt between the right pulmonary veins and inferior vena cava
The third form: additional cardiac and extracardiac malformations
Associated with abnormal bronchial anatomy, abnormal diaphragm, hemivertebrae, and anomalies of the genitourinary tract

31. Scimitar Syndrome At least 40% of patients are asymptomatic
The clinical symptoms usually manifest in the 2nd to 3rd decade of life
Fatigue and dyspnea with exertion
Recurrent pulmonary infection
In the infantile group, a higher prevalence of pulmonary hypertension has been reported
The clinical significance and prognosis depend to a large extent on the amount of the resulting left-right shunt

32. Scimitar Syndrome
The pulmonary vein descending along the right cardiac border (scimitar sign)

33. Congenital Cystic Adenomatoid Malformation
An overgrowth of bronchioles, with almost complete suppression of alveolar development between the 7th and 10th weeks of embryonic life
Characterized by a multicystic mass of pulmonary tissue with an abnormal proliferation of bronchial structures
It usually involves a single lobe

34. Congenital Cystic Adenomatoid Malformation
Classified into three histologic types
Type I: variable-size cysts, with at least one dominant cyst (>2 cm in diameter), most common (75%)
Type II: smaller, more uniform cysts less than 1 cm in diameter (10% to 15%)
Type III: a solid mass composed of bronchoalveolar microcysts, often causes death at birth

35. Congenital Cystic Adenomatoid Malformation
Type II
Type I
In older patients, cysts have an inflammatory component; this is due to the respiratory-lining and mucin-secreting cells
In severe cases, the lung may be hyperexpanded, with mediastinal shift, a flat hemidiaphragm, and herniation of the lung to the contralateral side
Type III
Type I

36. Congenital Cystic Adenomatoid Malformation
Symptoms
Prenatal: broad variation, ranging from an incidental finding to severe hydrops with mass effect and mediastinal shift
Postnatal: 1/2~2/3 will have some form of respiratory distress or compromise, including tachypnea, retractions, and cyanosis
Older patients: recurrent pulmonary infections

37. Congenital Lobar Emphysema
Result from a check-valve mechanism at the bronchial level that causes progressive hyperinflaction of the lung
Characterized by progressive overdistention of a lobe, sometimes two lobes
The most commonly affected lobe is the left upper lobe (42.2%), followed by the right middle lobe (35.3%), the right upper lobe (20.7%), and in each lower lobe (0.9%)

38. Congenital Lobar Emphysema
It is more common among males
May be associated with other anomalies (cardiovascular system is involved in 12%~14%)
Most patients become symptomatic during the neonatal period, most before 6 months of age
Respiratory distress is the most common
It becomes symptomatic in infancy (type I), in older children (type II), or is an incidental finding in asymptomatic patients (type III)
In 50%~55% of cases, the cause of congenital lobar emphysema is unknown
Areas of malacia or stenosis of the bronchial cartilage were found

39. Congenital Lobar Emphysema
Congenital lobar emphysema may be confused with pneumothorax or with a simple lung cyst or acquired cyst
Ipsilateral and contralateral atelectasis may occur
If the affected lobe is large and markedly expanded, the ipsilateral ribs may be separated and the hemidiaphragm depressed
There are bronchovascular markings within the overdistended lobe, and the adjacent lobe collapses are either caudad or cephalad but not medial, toward the hilum

40. Pulmonary Sequestration
Defined as an aberrant lung tissue mass that has no normal connection with the bronchial tree or with the pulmonary arteries
Arterial blood supply arises from the systemic arteries, usually the thoracic or abdominal aorta
Venous drainage is via the azygous system, the pulmonary veins, or the inferior vena cava
Divided into two types:
extralobar and intrapulmonary

41. Intralobar Sequestration
Contained within the lung and has a visceral pleura covering
It is located within the lower lobe in 98% of cases
It usually contains air within cystic lung tissue or air-fluid levels when infections are present
It is usually considered an acquired abnormality of the lung, due to recurrent infections and bronchial obstruction

42. Extralobar Sequestration
It is a mass of abnormal lung tissue that is surrounded by its own separate pleura
It is usually located in the posterior lower chest, and 90% are located on the left side
It is more common
Associated with diaphragmatic hernia, congenital heart disease, and congenital cystic adenomatoid malformation
Male : Female = 4 : 1

43. Pulmonary Sequestration
It has the appearance of a soft-tissue opacity in the posterior basal segment of the lung, with smooth or lobulated margins
Brochiectasis, subsegmental atelectasis, mediastinal shift, and prominence of the ipsilateral hilum are additional radiographic findings

44. Pulmonary Sequestration
CT scans show a soft-tissue cystic mass containing air or fluid, focal emphysema, and a hypervascular focus of lung tissue

45. Esophageal Anomalies Esophageal Atresia and Tracheoesophageal Fistula
Esophageal Duplications

46. Esophageal Atresia and Tracheoesophageal Fistula
It is the most common congenital malformation of the esophagus
It is thought to be due to a developmental disorder in formation and separation of the primitive foregut into trachea and esophagus
Intrauterine anoxia or stress with resulting vascular compromise may produce focal necrosis of the esophagus

47. Esophageal Atresia and Tracheoesophageal Fistula
In 25% of cases, it is associated with other gastrointestinal malformations such as imperforate anus, pyloric stenosis, duodenal atresia, annular pancreas
The "VACTERL" complex (vertebral, anal, cardiovascular, tracheoesophageal, renal, radial, and limb malformations)

48. Esophageal Atresia and Tracheoesophageal Fistula
It is generally suspected on the basis of polyhydramnios, inability to swallow saliva or milk, aspiration during early feedings, or failure to successfully pass a catheter into the stomach
Atelectasis and pneumonia involving the upper right lobe are seen in up to 50% of cases

49. Esophageal Atresia and Tracheoesophageal Fistula
A blind pouch of the proximal esophagus, distended with air
Include the abdomen to look for the presence of air in the gastrointestinal tract

50. Esophageal Duplications
It is the second most common duplications of the gastrointestinal tract after those of the ileum
The duplicated segment has a thick wall of smooth muscle and is lined with alimentary tract mucosa
Complete duplication is a rare malformation, often associated with gastric duplication
In the newborn and infant, symptoms are due to pressure on the adjacent lung or esophagus
The aberrant luminal recanalization theory proposed by Bremer is an adequate explanation for duplications in those portions of the gastrointestinal tract that go through the "solid stage," such as the esophagus, small bowel, and colon

51. Esophageal Duplications
Most often, duplications are
spherical cysts and are
usually located in the right
hemithorax
On plain chest radiographs,
they are usually seen as
posterior mediastinal
masses
In cystic esophageal duplication, the esophagogram shows the esophagus to be displaced to the side opposite the cystic mass or an intramural extramucosal mass

52. Esophageal Duplications
A duplication is sharply
marginated, has a homogeneous
near-water density, and is not
enhanced after intravenous
contrast material injection
Endoscopic sonography has proved to be a reliable method because it can demonstrate contiguity of the muscularis propria of the esophagus with the muscle layer of the cyst wall