AJR 2004; 183:1497-1506
© American Roentgen Ray Society
CT of Congenital Lung Lesions in Pediatric Patients
Pedro Daltro1,2,
Bradley L. Fricke3,
Iugiro Kuroki1,2,
Romeu Domingues1,2 and
Lane F. Donnelly3
1 Clinica de Diagnostico por Imagem, Barra da Tijuca, Rio de Janeiro,
Brazil.
2 Instituto Fernandes Figuera, Fundação Oswaldo Cruz, Rio de
Janeiro, Brazil.
3 Department of Radiology, Cincinnati Children's Hospital Medical Center, 3333
Burnet Ave., Cincinnati, OH 45229.
Received February 25, 2004;
accepted after revision April 2, 2004.
Address correspondence to L. F. Donnelly.
Introduction
Congenital lung lesions in children may involve the lung parenchyma,
bronchi, arterial supply, and venous drainage. Such lesions may present with
respiratory symptoms at birth or may be detected incidentally either before or
after birth. Chest radiography may detect many of these lesions. CT may be
useful in confirming the presence of the lesion, determining the extent of the
lesion, and defining associated abnormalities. Reconstructed data from CT
examinations displayed in either 3D or multiplanar formats can be particularly
helpful in delineating abnormalities of the bronchi and associated arterial
and venous structures. This pictorial essay reviews congenital lung lesions
and stresses the scenarios in which CT with reconstructed images may be
helpful.
Lung Agenesis–Hypoplasia Complex
Pulmonary agenesis is the complete absence of lung parenchyma with no trace
of bronchial or vascular supply
[1]. Imaging shows a diffuse
opacity of one hemithorax with hyperinflation of the contralateral lung and a
mediastinal shift towards the affected hemithorax
[1]. CT confirms the absence of
lung parenchyma, pulmonary artery, and bronchial structures on the affected
side (Fig. 1A,
1B,
1C,
1D). Other associated
abnormalities may be present on imaging.
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Fig. 1B. —Pulmonary agenesis in 2-month-old girl. Axial
contrast-enhanced CT scan shows main pulmonary artery (P) extends into right
pulmonary artery (arrows), which extends into right hemithorax. Note
absence of left pulmonary artery.
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Fig. 1C. —Pulmonary agenesis in 2-month-old girl. Coronal
reconstruction of CT scan shows trachea giving rise to right main bronchus
(arrows). Note absence of left main bronchus and absence of left
lung.
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Fig. 1D. —Pulmonary agenesis in 2-month-old girl. Coronal
reconstruction of CT scan shown at mediastinal window setting shows main
pulmonary artery (P) giving rise to right pulmonary artery (arrows).
Note absence of left pulmonary artery and left lung.
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In pulmonary aplasia, a rudimentary bronchus is present that ends in a
blind pouch with no evidence of pulmonary vasculature or lung parenchyma
[1]. Imaging findings are
similar to those of pulmonary agenesis, with the exception of a shortened
bronchus found in the abnormal hemithorax. CT confirms the presence of the
blind-ending bronchus (Fig. 2A,
2B).
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Fig. 2A. —Pulmonary aplasia in 5-month-old girl. Scout image from CT
shows absence of right lung with hyperexpansion of left lung. Note
blind-ending right main bronchus (arrows) arising from trachea.
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Fig. 2B. —Pulmonary aplasia in 5-month-old girl. Three-dimensional
reconstruction from CT scan shows blind-ending right main bronchus
(arrows) is minimally obscured by overlying artery. Note left
pulmonary artery (P). No right pulmonary artery is seen.
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Pulmonary hypoplasia refers to the presence of a bronchus and rudimentary
lung, with a decrease in the number and size of alveoli, airways, and vessels
[1]. CT can show asymmetrically
decreased lung parenchyma with narrowed airways and fewer branches in the
affected hemithorax and herniation with mediastinal shift of the contralateral
lung (Fig. 3A,
3B,
3C). Respiratory distress and
recurrent infections are common presentations, and associated anomalies may be
present [1].
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Fig. 3C. —Pulmonary hypoplasia in 1-year-old boy. Contrast-enhanced CT
scan at mediastinal window setting shows asymmetrically small left pulmonary
artery (arrows) as compared with right pulmonary artery (R).
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Pulmonary Artery Agenesis
Pulmonary artery agenesis is the complete absence of the right or left
pulmonary artery. This lesion is commonly associated with other cardiac
anomalies and is usually diagnosed incidentally
[2]. Chest radiography shows a
small affected lung and hilum and no identifiable pulmonary artery. The lung
may appear hyperlucent secondary to decreased pulmonary blood flow, but
without signs of air-trapping. CT confirms the absence of a pulmonary artery
and the lack of findings of air trapping and may show enlarged systemic
arteries (Fig. 4A,
4B,
4C,
4D). Treatment is conservative
[2].
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Fig. 4B. —Pulmonary artery agenesis in 14-year-old boy. CT scan at lung
window setting shows asymmetric lung volume, with left lung much larger than
right, and associated mediastinal shift. Note pulmonary vessels within
bilateral lungs have similar appearance without evidence of air trapping.
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Fig. 4C. —Pulmonary artery agenesis in 14-year-old boy. CT scan with IV
contrast enhancement shows main pulmonary artery (P) giving rise to left
pulmonary artery (L) and agenesis of right pulmonary artery
(arrow).
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Pulmonary Vein Atresia
Clinical manifestations of pulmonary vein atresia usually present in
infancy or childhood and include recurrent infection or hemoptysis
[3]. Radiography shows a small
hemithorax, mediastinal shift, and unilateral reticular opacities with septal
lines [3]. CT shows the absence
of the pulmonary vein connection to the left atrium, mediastinal collateral
vessels, and a disproportionately small ipsilateral pulmonary artery
[3] (Fig.
5A,
5B,
5C). Treatment options include
conservative management, coil embolization of systemic collaterals, and
resection [3].
Bronchial Atresia
Bronchial atresia is characterized by the obliteration and, usually, mucus
impaction of the distal lumen of a segmental bronchus with preservation of
distal branches [1]. Typically,
involvement is in only one segment—the apicoposterior segment of the
left upper lobe—but any lobe can be affected
[1]. CT often shows a hilar
mass, mucus-filled dilated bronchi, and overinflation of the affected lobe
secondary to air trapping from collateral bronchial channels
[2] (Fig.
6A,
6B). Most patients with
bronchial atresia are asymptomatic and do not require surgery
[2].
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Fig. 6A. —Bronchial atresia in 8-year-old boy. CT scan shown at lung
window setting shows three oval, fingerlike densities (arrows) in
right infrahilar region, affecting right middle lobe and right lower lobe.
Note hyperinflation of right lung as compared with left.
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Hypogenetic Lung Syndrome (Scimitar Syndrome)
Scimitar syndrome is associated with a hypoplastic lung and partial
anomalous venous return with systemic venous drainage
[1,
2,
4]. The right hemithorax is
almost always affected, and associated cardiovascular anomalies are not
uncommon [1,
2,
4]. Although children are
usually asymptomatic, with the diagnosis being made incidentally, symptoms
depend on associated abnormalities and children may present in infancy
[1]. Radiography reveals a
hypoplastic right lung with a curvilinear tubular area of increased opacity
(the scimitar) along the right heart border, signifying the anomalous draining
vein [1,
2] (Fig.
7A,
7B). Ipsilateral mediastinal
shift with an asymmetric, enlarged contralateral lung is present. CT can
confirm the diagnosis and provides additional information including the size
of the pulmonary artery, branching of the bronchi, and associated anomalies
[1]. Treatment is usually
conservative.
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Fig. 7A. —Hypogenetic lung syndrome (scimitar syndrome) in 6-year-old
girl. Coronary oriented maximum-intensity-projection image from
contrast-enhanced CT scan shows small right hemithorax as compared with left
hemithorax. Note anomalous pulmonary venous drainage of right lower lobe, with
anomalous vein (arrows) connecting to inferior vena cava.
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Congenital Lobar Emphysema
Congenital lobar emphysema usually involves a single lobe and presents with
respiratory distress in the neonate
[5,
6]. Initially, congenital lobar
emphysema may appear as a soft-tissue density related to retention of fetal
lung fluid [5]. Findings of air
trapping with lobar hyperinflation, mediastinal shift away from the involved
lung, and compression of the ipsilateral and contralateral lung develop
[5] (Fig.
8A,
8B,
8C). CT shows an expanded lobe
with attenuated vascular structures (Fig.
6A,
6B). Congenital lobar
emphysema can be life threatening and lobectomy has been the treatment of
choice [5], but recent evidence
shows that some patients do well with conservative management
[7].
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Fig. 8A. —Congenital lobar emphysema in newborn boy. Radiograph shows
hyperlucency and hyperexpansion of right upper lobe. Compressive atelectasis
is present in right middle lobe and right lower lobe. Note endotracheal and
nasogastric tubes.
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Fig. 8B. —Congenital lobar emphysema in newborn boy. Axial
contrast-enhanced CT scan at lung window setting shows hyperinflated right
upper lobe. Vessels within right upper lobe are attenuated and more spread
apart than those of left upper lobe.
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Fig. 8C. —Congenital lobar emphysema in newborn boy. Three-dimensional
surface-rendered CT scan shows hyperexpanded right upper lobe. Note
compressive atelectasis of right middle lobe and right lower lobe.
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Congenital Cystic Adenomatoid Malformation
Congenital cystic adenomatoid malformation accounts for 25% of all
congenital lung malformations and most commonly presents with respiratory
distress in newborns [1,
2,
5,
8]. These lesions are now often
diagnosed on prenatal sonography or MRI, and newborns can be asymptomatic at
birth. Congenital cystic adenomatoid malformation may present later in life,
with recurrent infection or hemoptysis
[8]. Imaging shows a mass with
a variable number of solid and cystic components
(Fig. 9). Congenital cystic
adenomatoid malformation communicates with the bronchial tree at birth and
therefore typically contains air soon after birth
[5]. The imaging appearance is
determined by the size and number of cysts
[5]. Lesions are typically
solitary with no lobar predilection
[5]. Stocker classified three
types of congenital cystic adenomatoid malformation: Type I consists of large
cysts; type II consists of small cysts; and type III shows lesions resembling
a homogeneous mass, with cysts only seen on microscopy
[1,
2,
5,
8]. Because of the risks of
recurrent infection and malignant potential, resection remains the current
treatment [5,
8].
Bronchogenic Cyst
Bronchogenic cysts are the most common cystic lesion of the mediastinum.
They usually present with recurrent infection or airway compression leading to
wheezing, atelectasis, and air trapping and often present later in childhood
than other congenital lung lesions
[2]. Imaging shows a
well-defined spheric mass (Fig.
10). Lesions are often mediastinal or perihilar but can occur
anywhere in the lung adjacent to the airway and do not contain air unless
infection is present. Treatment is surgical resection
[2].
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Fig. 10. —Bronchogenic cysts in 1-year-old boy. CT scan shows
fluid-attenuation mass (C) in mediastinum in subcarinal location. Lesion is
well defined and displaces mediastinal structures anteriorly.
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Pulmonary Sequestration
Pulmonary sequestration describes nonfunctioning lung parenchyma that do
not communicate with the tracheobronchial tree and have an anomalous systemic
arterial supply [2,
4]. Although clinical
presentation is often accompanied by recurrent infection, most commonly the
diagnosis is made incidentally
[2]. Sequestrations can either
be intralobar, in which the anomalous parenchyma are contained within visceral
pleura, or extralobar, with a separate pleural covering
[2,
4]. The most common location is
the left lower lobe. Sequestration appears as a persistent opacity or mass.
Lesions contain air only when superinfection is present. The diagnostic
imaging feature is a display of systemic arterial supply—typically
arising from the aorta (Fig.
11A,
11B). Imaging techniques such
as CT, MRI, and sonography can be used for diagnosis. Reconstructed CT scans
are useful in showing the anatomy of the systemic arterial supply. Symptomatic
lesions are treated with surgical resection
[4].
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Fig. 11A. —Bronchopulmonary sequestration in 3-year-old boy. Coronal
reconstruction of contrast-enhanced CT scan shows opacification within left
lower lobes (arrows). Note prominent arterial structures within
opacified lung.
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Pulmonary Arteriovenous Malformation
Pulmonary arteriovenous malformations are usually solitary but can be
multiple in certain genetic syndromes
[2]. Patients may present with
dyspnea, hemoptysis, cyanosis, or clubbing, or they may be asymptomatic
[2]. These lesions most
commonly occur in the lower lobes and are seen on chest radiography as round,
homogeneous masses. CT shows the anomalous feeding artery and draining vein
(Fig. 12). Large lesions are
typically treated with intravascular embolization (Fig.
13A,
13B) or, less commonly,
surgical resection [2].
Multiple lesions can be associated with syndromes such as Osler-Weber-Rendu
disease.
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Fig. 12. —Arteriovenous malformation in 11-year-old boy.
Maximum-intensity-projection rendered contrast-enhanced CT scan shows
arteriovenous malformation (A) with feeding artery (arrow) and
draining vein (arrowheads).
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Fig. 13A. —Multiple arteriovenous malformations in 9-year-old girl.
Three-dimensional reconstruction of CT scan after IV contrast enhancement
shows bilateral arterial venous malformation (A) with feeding arteries and
draining veins.
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Fig. 13B. —Multiple arteriovenous malformations in 9-year-old girl.
Coronary 3D image of contrast-enhanced CT after embolization shows
high-attenuation coils. Arteriovenous malformations and draining veins no
longer enhance.
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Introduction
Lung Agenesis-Hypoplasia Complex
