AJR 2000; 175:1005-1012
© American Roentgen Ray Society
Noninvasive Imaging of Bronchopulmonary Sequestration
Sheung-Fat Ko1,
Shu-Hang Ng1,
Tze-Yu Lee1,
Yung-Liang Wan1,
Chi-Di Liang2,
Jui-Wei Lin3,
Wei-Jen Chen3 and
Ming-Jeng Hsieh4
1
Department Radiology, Chang Gung Memorial Hospitals at Kaohsiung and Linkou,
Chang Gung University, 123 Ta-Pei Rd., Niao-Sung Hsiang, Kaohsiung Hsien 833,
Taiwan.
2
Department of Pediatrics, Chang Gung Memorial Hospital at Kaohsiung, Chang
Gung University, Kaohsiung Hsien 833, Taiwan.
3
Department of Pathology, Chang Gung Memorial Hospital at Kaohsiung, Chang Gung
University, Kaohsiung Hsien 833, Taiwan.
4
Department of Cardiovascular and Thoracic Surgery, Chang Gung Memorial
Hospital at Kaohsiung, Chang Gung University, Kaohsiung Hsien 833,
Taiwan.
Received February 14, 2000;
accepted after revision March 21, 2000.
Address correspondence to S-F Ko.
Introduction
Bronchopulmonary sequestration is an uncommon pulmonary disorder consisting
of a segment of nonfunctioning lung parenchyma that has no communication with
the tracheobronchial tree and receives its blood supply via an aberrant
systemic artery
[1,2,3,4].
Conventionally, bronchopulmonary sequestration has been categorized into
intralobar and extralobar forms. Intralobar bronchopulmonary sequestration
(75% of the cases) (Fig.
1A,1B,1C,1D,1E,1F)
is characterized by investment within the visceral pleura, a large aberrant
systemic artery, venous drainage via the pulmonary vein, and older age of
presentation and is uncommonly associated with other anomalies. Extralobar
bronchopulmonary sequestration (25% of the cases) (Fig.
2A,2B,2C,2D)
is characterized by separate pleural investment, a small aberrant systemic
artery, venous drainage via the azygos system, and neonatal presentation and
is commonly associated with other anomalies
[1,
2]. Various imaging techniques
have been used in the evaluation of bronchopulmonary sequestration
[2,3,4,5,6,7,8].
Bronchography and scintigraphy have now been abandoned, but chest radiography
remains an important screening tool
[1,2,3,4,5,6,7].
Traditionally, definitive diagnosis of bronchopulmonary sequestration relies
on invasive arteriographic display of the aberrant systemic artery
[1,2,3,4]
(Fig. 1D). Sonography, CT, and
MR imaging are noninvasive techniques that have been reported to be well
suited for evaluating bronchopulmonary sequestration
[2,3,4,5,6,7,8].
This pictorial essay seeks to highlight the appearance of the aberrant
systemic artery and to review the perplexing manifestations found on
noninvasive imaging techniques of surgically proven bronchopulmonary
sequestration encountered at our hospital.
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Fig. 1A. —15-year-old girl with intralobar bronchopulmonary sequestration who
presented with chronic left lower chest discomfort. Frontal chest radiograph
shows large well-defined homogeneous opacity (arrowheads) in left
lower lung field.
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Fig. 1B. —15-year-old girl with intralobar bronchopulmonary sequestration who
presented with chronic left lower chest discomfort. Helical CT scan with 3-mm
reconstruction interval shows mass with cystic components
(arrowheads) in left lower lobe. Note aberrant systemic artery
(arrow) originating from descending thoracic aorta.
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Fig. 1C. —15-year-old girl with intralobar bronchopulmonary sequestration who
presented with chronic left lower chest discomfort. CT angiogram with
maximum-intensity-projection reconstruction shows aberrant systemic artery
extending from descending thoracic aorta.
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Fig. 1D. —15-year-old girl with intralobar bronchopulmonary sequestration who
presented with chronic left lower chest discomfort. Digital subtraction
angiogram confirms findings (arrowhead) seen on C. Note venous
drainage via left inferior pulmonary vein (arrows).
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Fig. 1E. —15-year-old girl with intralobar bronchopulmonary sequestration who
presented with chronic left lower chest discomfort. Gross specimen of excised
left lower lobe reveals large mass (arrowheads) with numerous cystic
spaces. Mass and normal lung parenchyma are enclosed within visceral
pleura.
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Fig. 1F. —15-year-old girl with intralobar bronchopulmonary sequestration who
presented with chronic left lower chest discomfort. Photomicrograph of
histopathologic section shows multiple cystic spaces with mucin content or
intracystic hemorrhage. Cystic spaces are lined with respiratory epithelium,
intervening connective tissue, and acute and chronic inflammatory cells. (H
and E, x250)
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Fig. 2A. —1-month-old female infant with extralobar bronchopulmonary
sequestration between left lower lobe and left hemidiaphragm, who presented
with marked hypoglycemia as result of nesidioblastosis of pancreas and ectopic
pancreatic tissues in duodenum and small intestine. Chest radiograph shows
mild flattening of left hemidiaphragm (arrowheads) and blunting of
left costophrenic angle.
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Fig. 2B. —1-month-old female infant with extralobar bronchopulmonary
sequestration between left lower lobe and left hemidiaphragm, who presented
with marked hypoglycemia as result of nesidioblastosis of pancreas and ectopic
pancreatic tissues in duodenum and small intestine. Sonogram for screening for
pancreatic or other abdominal abnormalities incidentally reveals echogenic
mass with multiple cystic components (arrows) above left
hemidiaphragm. No abnormal vessel is seen.
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Fig. 2C. —1-month-old female infant with extralobar bronchopulmonary
sequestration between left lower lobe and left hemidiaphragm, who presented
with marked hypoglycemia as result of nesidioblastosis of pancreas and ectopic
pancreatic tissues in duodenum and small intestine. Helical CT scan with 1-mm
reconstruction interval shows inhomogeneous mass in posterior part of left
lower chest with small aberrant systemic artery (arrows) from
thoracolumbar aorta. Cystic components are less apparent on CT than on
sonography.
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Fig. 2D. —1-month-old female infant with extralobar bronchopulmonary
sequestration between left lower lobe and left hemidiaphragm, who presented
with marked hypoglycemia as result of nesidioblastosis of pancreas and ectopic
pancreatic tissues in duodenum and small intestine. Cut section of gross
specimen shows pyramid-shaped mass with multiple cysts invested with its own
pleura.
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Radiographic Appearance
Bronchopulmonary sequestration has a wide spectrum of imaging findings on
chest radiographs
[1,2,3,4,5,6,7].
Intralobar bronchopulmonary sequestration affects the lower lobes in 95% of
cases and the middle or upper lobes in 2% of cases
[1]. On a chest radiograph,
intralobar bronchopulmonary sequestration most commonly presents as either a
well-defined homogeneous opacity in the lung base
(Fig. 1A) or a solitary lung
nodule (Fig. 3A)
[1,2,3,4].
Air-fluid levels (Fig. 4A),
caused by bronchial communication, can be seen in 26% of cases
[1]. Pneumothorax may also
occur when cysts rupture into the pleural cavity
(Fig. 4A). Other findings
include recurrent pneumonia (Fig.
5A) or focal bronchiectasis
[1,2,3,4].
Intralobar bronchopulmonary sequestration appears as an irregular lesion
mimicking a malignant lung tumor (Fig.
6A) in 1.5% of cases
[1]. On rare occasions,
bronchopulmonary sequestration appears as an area of hyperradiolucency
(Fig. 7A). On the other hand,
extralobar bronchopulmonary sequestration is most commonly located between the
diaphragm and the lower lobe
[1]. It may be incidentally
found as a homogeneous mass or a small bump on the posterior medial
hemidiaphragm [1,
2] that may be subtle on a
chest radiograph (Fig. 2A).
Extralobar bronchopulmonary sequestration may communicate with the esophagus
or stomach. Barium esophagography is useful to display the presence of a
fistula and to detect any associated thoracic vascular anomalies
[1,
2].
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Fig. 3A. —Asymptomatic 46-year-old man with intralobar bronchopulmonary
sequestration. Chest radiograph incidentally reveals ovoid mass
(arrows) in posteromedial part of right lower lung field.
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Fig. 4A. —20-year-old woman with intralobar bronchopulmonary sequestration who
presented with chronic cough and acute right chest pain. Chest radiograph
shows cavitary lesion with air-fluid level in right middle lung field.
Pneumothorax (arrows) is also noted.
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Fig. 5A. —20-year-old woman with intralobar bronchopulmonary sequestration who
presented with recurrent fever and intractable cough with purulent sputum.
Chest radiograph shows lobar consolidation in left lower lung field.
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Fig. 7A. —1-year-old boy with intralobar bronchopulmonary sequestration who
presented with persistent cough. Chest radiograph shows focal hyperradiolucent
area (arrowheads) in right lower lung field.
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Sonographic Appearance
Hang et al. [4] have
advocated the use of sonography as a screening tool for bronchopulmonary
sequestration after chest radiography. On sonography, bronchopulmonary
sequestration usually appears as a well-defined or irregular homogeneous
echogenic solid mass, characteristically with an aberrant systemic artery
originating from the aorta [2,
4,
5]
(Fig. 8A). Occasionally,
bronchopulmonary sequestration exhibits a cystic or complex character
(Fig. 2B). Color and duplex
Doppler sonograms are helpful in analyzing the flow of the arterial supply
(Fig.
8A,8B)
and venous drainage [2,
4]. However, sonographic
detection of a small aberrant systemic artery may be difficult
(Fig. 2B), and the bony thorax,
normally aerated lung, or air in the cysts may limit the adequacy of
sonographic study
[2,3,4,5].
Nevertheless, sonographically guided fine-needle biopsy is useful in
diagnosing subdiaphragmatic bronchopulmonary sequestration if respiratory
epithelium is retrieved
[2].
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Fig. 8A. —18-year-old man with intralobar bronchopulmonary sequestration who
presented with cough. Left longitudinal color Doppler sonogram (in
black-and-white photograph) shows homogeneous echogenic mass with aberrant
vessel (arrow) originating from aorta (arrowheads).
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CT Appearance
Among various noninvasive imaging techniques, CT provides the best display
of the parenchymal abnormalities in bronchopulmonary sequestration
[2,3,4,
6]. Histologically, the
parenchymal changes of bronchopulmonary sequestration can easily be
differentiated into a common cystic-bronchiectatic form
(Fig. 1F) and a rare
pseudotumorous form [1,
6]. However, the number, size,
shape, and content of the cysts vary. This variation, coupled with the
presence of connective tissue, inflammatory cells, tracheobronchial
communication, and adjacent collateral air drift, result in various CT
appearances [1,
6]. Bronchopulmonary
sequestration most commonly appears as a homogeneous or inhomogeneous solid
mass, with or without definable cystic changes (Figs.
1B and
2C). It may also manifest as an
aggregate of multiple small cystic lesions with air or fluid content, a
well-defined cystic mass, or a large cavitary lesion with air-fluid level
(Figs. 3B,
4B, and
5B). Emphysematous changes at
the margins are a characteristic CT finding of bronchopulmonary sequestration
produced by collateral air drift (Fig.
9A,9B).
Occasionally, bronchopulmonary sequestration manifests as focal emphysema
generated by markedly hyperinflated alveoli
[6]
(Fig. 7B).
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Fig. 3B. —Asymptomatic 46-year-old man with intralobar bronchopulmonary
sequestration. CT scan shows well-defined, thin-walled cystic lesion with mild
focal thickening in posterior wall (arrow). Note atelectatic change
of posterobasal segment of right lower lobe (arrowheads).
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Fig. 4B. —20-year-old woman with intralobar bronchopulmonary sequestration who
presented with chronic cough and acute right chest pain. CT scan shows
multiple air-containing thin-walled cysts in right upper lobe, with air-fluid
level in largest one. Note pneumothorax compressing right upper lobe
(arrows).
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Fig. 5B. —20-year-old woman with intralobar bronchopulmonary sequestration who
presented with recurrent fever and intractable cough with purulent sputum. CT
scan shows numerous small air-containing and fluid-filled cysts in left lower
lobe.
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Fig. 9A. —36-year-old man with intralobar bronchopulmonary sequestration who
presented with intermittent hemoptysis. CT scan shows focal atelectatic change
in medial part of right lower lobe (arrows) with emphysematous
changes at border (arrowheads).
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Fig. 9B. —36-year-old man with intralobar bronchopulmonary sequestration who
presented with intermittent hemoptysis. Photomicrograph of histopathologic
section shows emphysematous change (arrows) of peripheral part of
bronchopulmonary sequestration and adjacent lung parenchyma. (H and E,
x250)
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Fig. 7B. —1-year-old boy with intralobar bronchopulmonary sequestration who
presented with persistent cough. CT scan shows multiple thin-walled cysts with
air-trapping appearance (arrowheads) in right lower lobe.
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The pseudotumorous bronchopulmonary sequestration form may appear as a
spiculated mass mimicking a malignant tumor
(Fig. 6B)
[1]. Preoperative
identification of the aberrant systemic artery in bronchopulmonary
sequestration is crucial to avoid accidental incision and catastrophic
hemorrhage [1,
2]. The aberrant systemic
artery may not consistently be seen on conventional CT. Ikezoe et al.
[6] reported that the aberrant
systemic artery was not visible in eight of 24 cases, probably because of the
small size of the arteries and unfavorable orientation. Because helical CT
offers faster scanning, multiplanar and CT angiographic display, and
retrospective data reconstructions with narrow intervals, it can facilitate
the display of the aberrant artery, which may be as small as 1 mm (Figs.
1B,
1C, and
2C). Furthermore, helical CT
allows simultaneous evaluation of the associated lung parenchyma and the
airway abnormalities [3]. The
venous drainage of bronchopulmonary sequestration may not be clearly shown on
CT [4,
6]. However, an obviously
enlarged azygos system (azygos plus hemiazygos diameters 
10 mm) associated
with a posterobasal chest lesion may suggest the diagnosis of bronchopulmonary
sequestration [7]
(Fig. 10). CT display of
premature atherosclerosis of the aberrant systemic artery with thrombosis has
also been reported [6].
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Fig. 10. —6-year-old girl with intralobar bronchopulmonary sequestration who
presented with recurrent fever and cough. CT scan shows inhomogeneous mass
(arrowheads) in left lower lobe and engorged azygos vein
(arrow).
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MR Imaging
MR imaging is well suited for the diagnosis of bronchopulmonary
sequestration because of its capacity to show the sequestration (which may be
a well-defined, irregular, or branchlike hyperintense mass) with precise
anatomic localization; define the size, origin, and course of both the
aberrant systemic artery and the venous drainage
[2,
3,
8] (Figs.
11 and
12A); and reveal the
associating abnormalities such as diaphragmatic hernia
[2]. However, MR imaging cannot
delineate focal thin-walled cysts or the emphysematous changes of
sequestration as clearly as CT. Two-dimensional time-of-flight MR angiography
can reveal the aberrant artery (Fig.
13A,13B),
but this method is limited by low spatial resolution and turbulent flow.
Breath-hold contrast-enhanced MR angiography can offer excellent display of
the aberrant artery without flow or respiratory artifacts
[8]
(Fig. 12B).
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Fig. 11. —4-month-old male infant with intralobar bronchopulmonary
sequestration who presented with nonproductive cough that had persisted since
birth. Coronal T1-weighted MR image shows hyperintense mass in left lower lobe
with large aberrant systemic artery (arrows) arising from descending
thoracic aorta with venous drainage (arrowheads) via hemiazygos and
azygos veins.
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Fig. 12A. —16-year-old girl with intralobar bronchopulmonary sequestration who
presented with cough and recurrent episodes of high fever. Reconstructed
oblique coronal T1-weighted MR image shows hyperintense mass with irregular
upper border in left lower lobe. Aberrant systemic artery
(arrowheads) originates from descending thoracic aorta, with venous
drainage via left inferior pulmonary vein (arrows).
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Fig. 13A. —46-year-old woman with intralobar bronchopulmonary sequestration who
presented with recurrent hemoptysis. Soft-tissue density mass in medial part
of left lung base was noted on CT (not shown). Time-of-flight MR angiogram in
coronal projection shows abnormal vessel (arrowheads) from abdominal
aorta tracking to mass in left lung base. Indistinct tubular shadow
(arrows) in retrocardiac region is also shown.
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Fig. 13B. —46-year-old woman with intralobar bronchopulmonary sequestration who
presented with recurrent hemoptysis. Soft-tissue density mass in medial part
of left lung base was noted on CT (not shown). Digital subtraction angiogram
confirms time-of-flight MR angiographic findings by revealing left lung base
mass (thick arrow) supplied by aberrant systemic artery
(arrowheads) and venous drainage via engorged left inferior pulmonary
vein (thin arrows).
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Fig. 12B. —16-year-old girl with intralobar bronchopulmonary sequestration who
presented with cough and recurrent episodes of high fever. Gadolinium-enhanced
three-dimensional MR angiogram in coronal oblique projection allows clear
display of aberrant systemic artery (arrowheads) arising from
descending aorta and mildly dilated left inferior pulmonary vein
(arrows).
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Differential Diagnosis
In symptomatic bronchopulmonary sequestration, the differential diagnosis
includes pneumonia, lung abscess, empyema, bronchiectasis, diaphragmatic
hernia, and tuberculosis. In asymptomatic bronchopulmonary sequestration, the
differential diagnosis includes bronchogenic or pericardial cyst, bronchial
atresia, lobar emphysema, cystic adenomatoid malformation, arteriovenous
fistula, bronchial adenoma, and lung tumor
[1,
2,
5,
6].
Conclusion
The algorithm for studying suspected bronchopulmonary sequestration after
initial radiographic studies remains controversial
[2,3,4,5,6,7,8].
With familiarity of the complex imaging findings, the diagnosis of
bronchopulmonary sequestration can be suggested by findings on conventional
chest radiography and established by revealing the aberrant systemic artery on
sonography, CT, and MR imaging.
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Top
Introduction
Radiographic Appearance
