DOI:10.2214/AJR.05.0155
AJR 2005; 185:1663-1664
© American Roentgen Ray Society
MDCT Demonstration of Intralobar Pulmonary Sequestration of the Right Upper Lobe in an Adult
Gilbert R. Ferretti,
François Blanc Jouvan and
Max Coulomb
CHU Grenoblem
Grenoble, France
We present the chest radiographic and CT findings of a rare case of right
upper lobe intralobar sequestration in an adult. Only a few pediatric cases
have been reported in the literature describing this anatomic location of a
sequestration [1,
2].
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Fig. 1A —23-year-old asymptomatic woman with right upper lobe
sequestration. Posteroanterior chest radiograph shows hyperlucency of right
upper lobe and tortuous tubular structure originating from right hilum
(arrow).
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Fig. 1B —23-year-old asymptomatic woman with right upper lobe
sequestration. High-resolution CT at full inspiration shows hyperlucent
abnormal lung parenchyma located externally to right upper lobe, clearly
separated from it by unusual accessory fissure. This image shows abnormal
vessel originating from descending aorta (arrow), abnormal vein
draining into right upper pulmonary vein (arrowhead), and cystic
bronchiectasis (double arrow).
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A 23-year-old asymptomatic woman underwent routine chest radiography
(Fig. 1A) that showed an area
of hyperlucency and a tortuous tubular structure originating from the right
hilum raising high suspicion of pulmonary arteriovenous malformation. MDCT was
then performed using 1-mm slice thickness and contrast material injection.
Then, a series of expiratory high-resolution CT scans was obtained. CT showed
abnormal lung parenchyma in the right lung, distinct from the right upper lobe
and clearly separated from it by an unusual accessory fissure that was
perforated by two large vessels, one originating from the descending aorta
(Fig. 1B) and the other
draining into the right upper pulmonary vein, as shown on maximum intensity
projection reconstruction (Fig.
1C). On inspiratory CT, the supernumerary lung parenchyma was
hyperlucent compared with the right lung. Bronchiectasis was identified within
the sequestrated lung (Fig.
1B). No communication was shown between the right bronchial tree
and the sequestrated lung (Fig.
1D). Air trapping occurred in the sequestrated lung. The patient
was asymptomatic and refused surgery.
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Fig. 1C —23-year-old asymptomatic woman with right upper lobe
sequestration. MDCT angiography with maximum intensity projection
reconstruction shows aberrant systemic artery extending from descending aorta
(arrow) and aberrant pulmonary vein (arrowhead) draining
into right upper pulmonary vein.
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Fig. 1D —23-year-old asymptomatic woman with right upper lobe
sequestration. Coronal minimal intensity projection shows no visible
communication between right bronchial tree and sequestered lung.
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Pulmonary sequestration is an infrequent congenital pulmonary disorder
defined by nonfunctional and dysplastic pulmonary tissue lacking a normal
connection with the tracheobronchial tree and the pulmonary arteries
[1]. The diagnosis of
sequestration relies on imaging techniques, mainly helical CT angiography
[3], that can identify each of
the components of the sequestration pattern
[1]: sequestered or dysplastic
lung mass, aberrant arterial supply, and anomalous venous drainage. Intralobar
sequestration (75% of cases) occurs in the normal lung parenchyma and does not
have a separate pleural lining. The arterial supply usually originates from
the aorta or its branches, and the venous return is usually (95% of cases)
into the pulmonary veins.
Intralobar sequestrations are usually found within the lower lobes, as
emphasized in the review of the literature by Savic et al.
[1], who found that 97.75% of
400 intralobar sequestrations were in such location. Only eight cases (2%) in
this series were found in the upper lobes, mainly in the right side (6 of 8).
Upper lobe sequestration may appear as an area of hyperradiolucency
[4], pulmonary mass
[2], or cystic pulmonary mass
[1]. In the present case, CT
clearly showed that the sequestrated lung lacked normal communication with the
tracheobronchial tree in the right lung. However, the sequestration appeared
as an area of hyperlucency that increased at the end of forced expiration,
confirming air trapping within the sequestration. This feature supports the
hypothesis of collateral pathways between the sequestration and the right lung
through pores of Kohn and probably located at the level of the lung parenchyma
surrounding the vascular pedicle of the sequestration
[4].
References
- Savic B, Birtel FJ, Tholen W, Funke HD, Knoche R. Lung
sequestration: report of seven cases and review of 540 published cases.
Thorax 1979; 34:96
-101[Abstract/Free Full Text]
- Hoeffel JC, Bernard C. Pulmonary sequestration of the upper lobe in
children. Radiology 1986;160
: 513-514[Abstract/Free Full Text]
- Lee EY, Siegel MJ, Sierra LM, Foglia RP. Evaluation of
angioarchitecture of pulmonary sequestration in pediatric patients using 3D
MDCT angiography. AJR 2004;183
: 183-188[Abstract/Free Full Text]
- Stern EJ, Webb WR, Warnock ML, Salmon CJ. Bronchopulmonary
sequestration: dynamic, ultrafast, high-resolution CT evidence of air
trapping. AJR 1991;157
: 947-949[Free Full Text]
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