PULMONARY SEQUESTRATION

1. PULMONARY
SEQUESTRATION
-DR. PRAPULLA CHANDRA

2. • INTRODUCTION
• PATHOGENESIS
• TYPES
• PATHOLOGY
• CLINICAL PRESENTATION
• ASSOCIATED ANOMALIES
• EVALUATION
• DIFFERENTIAL DIAGNOSIS
• TREATMENT
• SUMMARY

3. INTRODUCTION
• Bronchopulmonary sequestration (BPS) or sequestration is a
rare congenital abnormality of the lower respiratory tract.
• It consists of a non-functioning mass of lung tissue that lacks
normal communication with tracheobronchial tree and receives
its arterial blood supply from systemic circulation.
- UPTODATE 2016

4. • Bronchopulmonary sequestrations constitute approximately
0.15-6.4% of all congenital pulmonary malformations.
• Anatomically classified as
- Intra lobar Sequestration (ILS) – M/C
- Extra lobar Sequestration (ELS)

5. • INTRALOBAR SEQUESTRATION (ILS) : - 75%
- Located within the normal lobe and does not have its
own visceral pleura.
• EXTRALOBAR SEQUESTRATION (ELS) : - 25%
- Located outside the normal lung and has its own visceral
pleura.

6. INTRALOBAR (75%)
Visceral pleura
Adults (recurrent pneumonia)
15% congenital anomalies
associated.
EXTRALOBAR (25%)
Own pleural covering
First six months
50% congenital anomalies associated
(diaphragmatic hernia, cardiac, hybrid
forms CPAM/sequestration)

7. • Rare types :-
- Hybrid BPS/CPAM lesions :- BPS occurs in combination
with CPAM. These hybrid lesions have histological features of
CPAM and blood supply from a systemic artery.
- Bronchopulmonary-foregut malformation (BPFM)-
A Rare variant of sequestration where sequestrated lung tissue
is connected to the gastrointestinal tract.

8. PATHOGENESIS
• The most frequently supported theory of sequestration
involves formation of accessory lung bud that develops from
the ventral aspect of the primitive foregut.
• The pleuripotent tissue from this additional lung bud migrates
in a caudal direction with the normally developing lung.

9. • The accessory lung bud receives its blood supply from
vessels that connect to the aorta and cover the primitive
foregut.
• These attachments to the aorta remain to form the
systemic arterial supply of the sequestration.

10. • Early embryologic development of the accessory lung bud in
pseudoglandular stage (5-17weeks of gestation) results in
formation of the sequestration within normal lung tissue. This
sequestration is encased within the same pleural covering of
normal lung resulting in the Intrapulmonary OR Intralobar
sequestration
• Later development of the accessory lung bud results in the
Extralobar OR Extrapulmonary type that may give rise to
communication with the GI tract.

11. INTRALOBAR SEQUESTRATION
• ILS are located within a normal lobe and lack their own
visceral pleura.
• Accounts for 75% of BPS.
• Males and females are equally affected.
• Most occur in lower lobes, 60% located in posterior basal
segment of left lower lobe.

12. • The right lower lobe may be affected in approximately one-
third of cases
• Generally do not have communication with tracheobronchial
tree.
• Intralobar sequestration usually present in late childhood or in
young adults.
• Arterial blood supply is by lower THORACIC AORTA or
upper Abdominal aorta and Venous drainage is usually via the
pulmonary veins

13. • Infrequently, in 10% - 15% bronchopulmonary
foregut malformations and skeletal anomalies
(like scoliosis and rib anomalies) may be
associated.

14. • Within visceral pleura
of normal lobe
• Arterial supply by
thoracic aorta
• Venous drainage into
Pulmonary veins

15. EXTRALOBAR SEQUESTRATION
• Extra pulmonary sequestrations are located outside the
normal lung and have their own visceral pleura, with a
pedicle that contains the vascular connections.
• Accounts for 25% of BPS.
• Male predominance.
• ELS are more common on the left side, m/c between the left
lower lobe and hemi diaphragm (80%).
• They may also be found within or below the diaphragm or in
retroperitoneum.

16. • They are associated with other congenital malformations in
more than 50% of cases.
• They may connect to the gastrointestinal tract or rarely to
intrapulmonary structures.
• As intrapulmonary connections are uncommon in ELS,
infectious complications are also uncommon.

17. • Extralobar sequestration is typically supplied by a systemic
artery arising directly from the THORACIC aorta. The vessel
is usually small with low flow.
• Its venous drainage is usually through azygos–hemiazygos
system.

18. • Accessory lung tissue
surrounded by its own pleura
• Arterial supply by thoracic aorta
• Venous drainage into systemic
veins

19. PATHOLOGY
• On cut sections, the INTRALOBAR sequestration
comprises fibrotic and consolidated lung parenchyma that
frequently contains multiple cystic areas.
• The cysts may contain fluid, infected purulent material or
may be predominantly air filled – in which case, the cysts
have partial communication with the tracheobronchial tree.

21. • Histologically, intralobar sequestration is characterized by
changes of chronic inflammation and fibrosis with cystic
changes.
• Superimposed changes of acute infection may be present.
The alveoli that border the sequestered lung may be
emphysematous.

23. Fig. 1. Postoperative histopathology of a patient with intralobar sequestration
(haematoxylin–eosin stain, 40 magnification). The alveolar spaces are
filled with haemorrhage, oedema and chronic inflammatory infiltrate. Few
thick-walled blood vessels and areas of bronchial dilatation are also seen.

24. PATHOLOGY…
• EXTRALOBAR SEQUESTRATION is typically a single,
well circumscribed lesion covered by a mesothelial layer
(pleural envelope).
• Its surface may show a reticular pattern due to presence of
dilated subpleural lymphatics.
• On cut section the lesion is firm and homogenous.

25. • Microscopically, extralobar sequestration resembles normal
lung tissue, except for dilatation of bronchioles and alveolar
ducts and alveoli within the lesion.
• A well formed bronchus is identifiable in approximately half
the cases, typically located at one edge of the lesion.

26. CLINICAL PRESENTATION
• The clinical features of BPS are variable and depends upon
the type, size and location of the lesion.
• Most infants are asymptomatic at birth.
• If symptomatic, may present with respiratory distress at birth
or in the neonatal period, usually due to large lesions that
limit the volume of normal lung.

27. • The most common symptomatic presentation after neonatal
period is with pulmonary infection, typically presenting as
fever and cough, sometimes hemoptysis or chest pain, in pts
with ILS.
• Pts with ELS unlikely to develop infection.
• Rarely may present with heart failure due to excessive flow
through aberrant artery.

28. ASSOCIATED ANOMALIES
• More than half ( 50–65%) of patients with extralobar
sequestration have associated congenital anomalies, the most
common congenital diaphragmatic hernia seen in 20–30%.
• Various other anomalies have been reported in association
including bronchogenic cyst, foregut duplication, ectopic
pancreas and vertebral anomalies.
• Infants with large BPS may have pulmonary hypoplasia due to
mass effects in utero.

30. EVALUATION
PRENATAL :
-on prenatal ultrasound, BPS appears as homogenous
echogenic thoracic mass, usually solid appearing, triangular
and often located in lower hemithorax adjacent to the
diaphragm.
POSTNATAL :
- First step is chest radiograph.

31. • CHEST RADIOGRAPH :
-Sequestrations typically appear as a uniform dense mass
within the thoracic cavity or lung parenchyma.
- recurrent infections in ILS can lead to cystic areas within
the mass.
- Air-fluid levels in case of bronchial communication.

33. a) shows a cavitary lesion in right lower zone, in
the retrocardiac location (arrows).

34. • Computed tomography (CT) :
- Most common appearance is a solid mass that may be
homogenous or heterogenous, sometimes with cystic changes.
- Less frequently, a large cavitary lesion with an air-fluid
level, a collection of many small cystic lesions with air or
fluid.
- Emphysematous changes at the margin of the lesion ar
characteristic.

37. The CTaxial image in lung window (b) shows a
large thin-walled cavity with multiple
septations and an air-fluid level in the medical
basal segment of right lower lobe (arrow).

38. The CT shows presence of a large abnormal artery arising from the
thoracic descending aorta (c) and supplying a portion of the left lower lobe
including the posterior basal segment. Lung window (d)
shows an area of emphysema in the left lower
lobe, around the abnormal vessel.

39. A 31-year-old man presented with recurrent
chest infection. Chest radiograph shows a subtle nodular opacity in the right lower
zone (arrow in a). Axial CT sections (b,c) show a aberrant systemic artery arising
from the descending thoracic aorta supplying a sequestered segment in right
lower lobe.

40. MRI
• This is a safe and non-invasive alternative imaging method,
which may be useful.
• MRI provides an excellent observation of the supplying
systemic arterial anatomy.
• MR imaging can also depict the pulmonary venous return of
the lesion and the relationship of the draining vein to the
cardiac chambers.

41. ANGIOGRAPHY
• Traditionally, Angiography has been considered as the gold
standard for diagnosis of pulmonary sequestration by virtue
of its excellent depiction of the arterial and venous anatomy
but now it is replaced by
multidetector CT or MRI angiography

42. • Invasive catheter angiography may be helpful as a diagnostic
procedure in those select cases where the clinical and
radiological suspicion for sequestration is high, but a
supplying systemic vessel cannot be shown using CT or MR
angiographic techniques.

43. DSA of the patient shows blush within the sequestered lung segment
on the descending thoracic
aorta run (arrow in f). On selective cannulation of the supplying artery
arising from the thoracic aorta (g), the aberrant vessel is better seen

45. CT ANGIOGRAPHY
• Multidetector CT angiography has emerged as the imaging
technique of choice for preoperative evaluation of pulmonary
sequestration in both the paediatric and in the adult
population.
• Computed tomography has the advantage of being able to
show the pulmonary parenchymal abnormality as well as the
arterial and venous anatomy all in a single examination.

46. Computed tomographic angiography images of a 7-year-old male show the origin of an
aberrant systemic artery from the aorta (single arrow in a) supplying a sequestered
segment in the right lower lobe and venous drainage of the lesion through the
pulmonary vein into left atrium (double arrows in b) –classical features of intralobar
sequestration

47. CT sagital view showing
a feeding artery arising
from the aorta and
irrigating the pulmonary
mass

49. Maximum intensity projection (a) and surface-shaded display (b) images
of the patient shown in Figure 4; the aberrant vessel (arrow) is
seen arising from the descending thoracic
aorta.

50. Contrast-enhanced MR angiography maximum intensity projection
image (c) also shows the abnormal systemic artery supplying the
left lower lobe (arrow) with venous drainage into the left
hemiazygos system (arrow in d).

51. NUCLEAR SCAN
• Radionuclide angiography is a non-invasive technique that
has been used to show the systemic arterial supply to a
pulmonary sequestration.
• The sequestration may be seen as an area of lung having a
relative lack of perfusion during the pulmonary arterial phase
followed by perfusion during the systemic phase

52. 99Tc pertechnetate scan of the patient shown in Figure 9. An aberrant vessel is seen running
parallel to the descending aorta in the blood pool phase of 99Tc pertechnetate scan (arrow in
a). Perfusion scan shows a defect in the posteromedialbasal segment of right lower lobe (b).

53. PROTOCOL FOR EVALUATION
• Immediate advanced imaging with CT/MRI for pts with high risk :
- Any symptoms (respiratory distress)
- Large BPS ( >20% of lobe involved)
- B/l or multifocal cysts, pneumothorax or a pleuropulmonary
blastoma
• The purpose of the advanced imaging is to make the diagnosis and
identify the aberrant artery and to help with surgical planning.

54. • Advanced imaging may help to distinguish among ILS, ELS
and hybrid lesions, but is not completely reliable in making
these distinctions.
• The final definitive diagnosis is made only by
PATHOLOGICAL EXAMINATION after surgical
resection.

55. DIFFERENTIAL DIAGNOSIS
• Congenital pulmonary airway malformations (CPAM)
- CPAM can be differentiated from BPS by the presence of
connection to tracheobronchial tree and blood supply from
pulmonary circulation.

56. MANAGEMENT
• SYMPTOMATIC PTS :
• - All pts require surgical excision which is curative and
associated with minimal morbidity.
• In ILS, complete excision requires lobectomy or segmental
resection where as for ELS, simple resection is sufficient.
• All vascular connections to the lesion must be identified and
ligated.
• Thoracoscopic lobectomy can be done.

57. Large aberrant artery (thick arrow) is seen arising from the aorta
(A), which is exposed after retracting the heart (H), and left
hemidiaphragm (D). The draining vein (thin arrow) is seen medial
to the abnormal segment of lung (L).

58. • ASYMPTOMATIC PTS :
• - In high risk pts, early surgical resection to be done.
• - In low risk pts, surgical resection or observation.

60. SUMMARY
• Bronchopulmonary Sequestration is a rare congenital
abnormality of lower respiratory tract.
• It consists of a non-functioning mass of lung tissue that lacks
normal communication with tracheobronchial tree and
receives it blood supply from the systemic circulation.
• An intralobar sequestration (ILS) is located within a normal
lobe and lacks its own visceral pleura whereas An extralobar
sequestration (ELS) is located outside the normal lung with
its own visceral pleura.

61. • Clinical presentation depends on type, size and location of the
lesion.
• BPS can be detected by prenatal ultrasound & they may regress
during gestation in most cases or may progress.
• The affected newborn is usually asymptomatic, sometimes may
present with respiratory distress.
• On chest x-ray, typically appears as a uniformly dense mass
within the pulmonary parenchyma. Recurrent infections can lead
to cystic areas within the mass, and air-fluid levels if
communicates with a bronchus.

62. • Infants presenting with respiratory distress are treated with
surgical excision.
• For asymptomatic pts of any age with high risk for
developing complications, surgical resection rather than
observation.
• Without high risk characteristics, conservative management
with observation.

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