1. CONGENITAL ABNORMALITIES OF THE LUNG
Damian Gimpel
Waikato Cardiothoracic Unit

2. Take home messages
Many of these lung lesions can be diagnosed in utero.
For some large cystic lung lesions it is possible to intervene prenatally
The clinical presentation of these congenital lesions varies considerably, from a neonate in extremis to an asymptomatic adult.
Resection of the affected portion of the lung nearly always will be necessary.
Long-term results are generally very good.

3. Embryology

4. embryology
The lung parenchyma and vascular supply develop initially separate from one another.
During the embryonic phase of pulmonary development, as early as the third week of gestation, the lung buds begin as outpouchings of the primitive foregut.

5. embryology
Over the next 3 weeks, the lungs develop five distinct components ultimately to become the lobes.
It is during this phase that the pulmonary arteries and veins become associated with the developing lung buds.
The pulmonary arteries arise from the right and left sixth aortic arches and extend toward the developing lung bud

6. embryology
The pulmonary veins begin as an outgrowth of the dorsal wall of the atrium
divides into right and left pulmonary veins that then extend into the lung at the same time as the arterial development
The common pulmonary vein then becomes incorporated into the atrial wall as it develops

7. The pulmonary arteries follow the bronchi, but the veins do not.
embryology
The pulmonary arteries follow the bronchi, but the veins do not.

8. embryology
canalicular phase, the basic components to air exchange beginto develop, and by 28 weeks of gestation this pattern is firmly in place.
development of type I and type II pneumocytes.
alveolar period, these distal air spaces become more complex and multiply in numbers, forming mature alveoli.
After birth, there is a continued increase in the number of alveoli until approximately age 8 years. From that point further, the alveolar size increases up to age 21.

9. FAILURE OF DEVELOPMENT OF THE LUNG BUD
Agenesis
Aplasia
hypoplasia

10. agenesis result of failure of the primitive lung bud to develop
This can be a bilateral process - universally fatal. The trachea ends in primitive lung tissue or just blindly
Unilateral pulmonary agenesis - associated with other congenital anomalies, particularly when the right lung is absent
No known chromosomal aberrations have been identified with this process. Prognosis

11. agenesis
The presence of esophageal atresia or tracheoesophageal fistula has a particularly poor prognosis
Many patients are asymptomatic because the total volume of lung tissue present can be almost normal due to compensatory growth of the contralateral lung
The diagnosis may be made antenatally with ultrasound

12. agenesis
Pulmonary function tests may demonstrate evidence of airway obstruction secondary to stretching of the main stem bronchus across the mediastinal structures.
the overall survival of infants born with unilateral agenesis of the lung is somewhat poor, presumably because of the other associated anomalies but also due to airway issues related to the mediastinal shift and risk of infections.

13. agenesis

14. Aplasia
Aplasia of the lung is essentially the same as agenesis from a functional standpoint
In this case, a bronchial stump is present
This may be a source for recurrent infections
In those cases, resection of this stump may be indicated

15. hypoplasia
Hypoplasia of the lung can occur as a primary process or be related to other conditions that compromise the thoracic space available for lung growth (i.e. diaphragmatic hernia)
It is defined as deficient or incomplete development of one or both lungs.

17. hypoplasia
Pulmonary hypertension frequently accompanies lung hypoplasia because of the diminished pulmonary vasculature
Clinical manifestations of pulmonary hypoplasia depend on the volume of lung present but can include severe respiratory distress and cyanosis

18. hypoplasia
This may occur in up to 20% of infants born after premature rupture of membranes at 15 to 28 weeks of gestation
It is suspected in an infant with respiratory insufficiency and small lungs on chest radiography
The lungs fail to develop to normal size but contain the usual distribution of bronchi. There are decreased numbers of alveolar ducts and alveoli for the number of bronchioles microscopically. The cause is unknown, and themortality rate is high

19. Congenital Lobar Emphysema
CLE occurs when there is an obstruction in the bronchial tree that produces overexpansion of the air spaces of a segment or lobe of the lung
In contrast to acquired chronic obstructive pulmonary disease seen in adults, the parenchyma itself is not destroyed, showing only air space enlargement

20. Congenital Lobar Emphysema
inadequate development of the cartilage in the bronchi during the 18th week of gestation
Almost half of the patients with this diagnosis have a distinct abnormality in the bronchus leading to the affected lobe
abnormal mucous folds, intrinsic webs, bronchial stenosis, bronchomalacia

21. Congenital Lobar Emphysema
It is also possible for CLE to develop from extrinsic compression of the bronchus by enlarged pulmonary arteries
large left-to-right shunt or tetralogy of Fallot  enlarged central pulmonary arteries.
This accounts for a small percentage of cases of CLE

22. Congenital Lobar Emphysema
At least half of patients with CLE have no obvious abnormalit in the bronchus
CLE may arise because of a so-called polyalveolar lobe. In this disease, there is a significant increase in alveolar number, outstripping the number of bronchi leading to them
Air may enter these alveoli via collaterals and have no way to get out, resulting in overdistention of the affected lobe and thus CLE

23. Congenital Lobar Emphysema
The upper lobes, particularly the left upper lobe, are affected more often than the lower lobes
These lesions occur in the left upper lobe approximately 40% of the time
in the right middle lobe in 35% of cases
the right upper lobe in 20%
males two or three times more frequently than in females

24. Congenital Lobar Emphysema
The diagnosis is seldom made prenatally by ultrasound
This anomaly has a variable clinical presentation
Most infants develop symptoms of tachypnea, cough, and/or wheezing within a few days after birth.
Symptoms usually progress and may lead to severe respiratory distress if the hyper expansion is sufficient to compress the trachea. Approximately half of patients with present within the first month of life. A few present as adults

25. Congenital Lobar Emphysema
Physical examination typically demonstrates diminished breath sounds on the affected side
chest may be significantly larger when viewed externally
The diagnosis is usually made on the basis of the chest radiograph
hyperlucency on the affected side with mediastinal shift to the opposite side, depression of the diaphragm, and compression atelectasis of the remaining normal lung

26. Congenital Lobar Emphysema
CT of the chest is often helpful to establish the diagnosis, detect a possible underlying cause, and rule out foreign body aspiration
Bronchoscopy may be helpful in defining extrinsic compression, but do not perform it if the infant is in severe respiratory distress

27. Congenital Lobar Emphysema
Patients with isolated CLE who are symptomatic undergo thoracotomy with resection of the affected lobe
Positive-pressure ventilation during the procedures can pose significant problems: worsening of the air trapping and further shift of the mediastinum with consequent hemodynamic instability
The surgical mortality rate for CLE is approximately 15% and depends on the associated anomalies, which are usually cardiac

28. Congenital Lobar Emphysema
It is clear that, in some patients with minimal or no symptoms, CLE can be managed conservatively
Closely monitor these patients with serial chest radiographs and ventilation perfusion lung scans

29. Congenital Lobar Emphysema

30. Congenital Cystic Adenomatoid Malformation
segmental bronchial atresia, perhaps resulting from primary disruption during fetal lung bud development or from disruption of the fetal bronchial circulation
Lung growth beyond the atretic segment becomes dysplastic and may take on one of three distinct types

31. Congenital Cystic Adenomatoid Malformation
Type I (55% of cases) consists of large cystic spaces within a single pulmonary lobe
Type II (40%) appears as numerous small cysts less than 20 mm in diameter
Type III (5%) has no cysts but is a solid mass of adenomatoid hyperplasia or bronchial structures

32. Congenital Cystic Adenomatoid Malformation

33. Congenital Cystic Adenomatoid Malformation

34. Congenital Cystic Adenomatoid Malformation
Some lesions regress, as noted earlier, complicating the decision about intervening
Regression has been noted both antenatally by ultrasonography and in the fi rst few months after birth

35. Congenital Cystic Adenomatoid Malformation
The malignancies reported in association with CCAM include pleuropulmonary blastoma, rhabdomyosarcoma, squamous cell carcinoma and bronchioloalveolar carcinoma.
Bronchioloalveolar carcinoma is the most common neoplasm to arise in a CCAM, and it almost always occurs in Stocker type I lesions.

36. Congenital Cystic Adenomatoid Malformation
Prenatal treatment of CCAM includes resection and drainage of the cysts
Drainage of cysts prenatally, using a pleuroamniotic shunt, may be performed if the mass is compromising contralateral lung development or causing hydrops
The mortality rate for this intervention is approximately 30% for the fetus

37. Congenital Cystic Adenomatoid Malformation

38. Sequestration
Pulmonary sequestration is typically separated into two types
extralobar and intralobar

39. The common element in these two distinct pulmonary lesions is:
Sequestration
The common element in these two distinct pulmonary lesions is:
absence of communication with the tracheobronchial tree and pulmonary arterial vasculature

40. Extralobar sequestration:
mass of abnormal lung tissue that is completely separate from the remaining lung and has its own pleural investment

41. Sequestration

42. Sequestration

43. Sequestration

44. Sequestration
Intralobar sequestration is considered a congenital lesion
The diagnostic features are abnormal pulmonary tissue with no direct bronchial communication and a systemic arterial supply

45. Bronchogenic Cysts

46. PULMONARY ARTERIOVENOUS MALFORMATIONS
an abnormal connection between a pulmonary artery and vein that bypasses the alveolocapillary complex
right-to-left shunting and, subsequently, a varying degree of cyanosis

47. Take home messages
Many of these lung lesions can be diagnosed in utero.
For some large cystic lung lesions it is possible to intervene prenatally
The clinical presentation of these congenital lesions varies considerably, from a neonate in extremis to an asymptomatic adult.
Resection of the affected portion of the lung nearly always will be necessary.
Long-term results are generally very good.