Ultrasound Obstet Gynecol 2006; 27: 214–216
Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/uog.2667
Prenatal detection and evaluation of an extralobar
pulmonary sequestration in the posterior mediastinum
D. YORK*, A. SWARTZ†, A. JOHNSON†, J. FIELDING‡ and J. D. PHILLIPS*
Departments of *Surgery, †Obstetrics and Gynecology and ‡Radiology, University of North Carolina, School of Medicine, Chapel Hill,
KEYWORDS: magnetic resonance imaging; mediastinum; prenatal detection; pulmonary sequestration; ultrasound
Extralobar pulmonary sequestration (EPS) is a rare
developmental anomaly with aberrant nonfunctioning
parenchymal tissue, associated with an increased risk
of perinatal morbidity and, rarely, mortality owing to
possible neonatal respiratory distress. In most cases
supernumerary lobes are detected as isolated intra- or
extrapleural lesions with independent systemic arterial
blood supply. We report an atypical case of prenatal
detection and perinatal outcome of a mediastinal EPS.
Copyright 2006 ISUOG. Published by John Wiley &
A 24-year-old gravida 2 para 1, was referred to our
unit at 21 weeks’ gestation for a targeted fetal ultrasound
heart during a screening ultrasound scan performed at an
outside facility. A hyperechoic midlinemass was identified
measuring 1.6 × 1.3 × 1.9 cm, which appeared to be
immediately subdiaphragmatic (Figure 1). The medial
aspect of the right atrium was obscured by the mass
(Figure 2). Power Doppler blood flow imaging suggested
venous drainage into the inferior vena cava. The arterial
blood supply to the mass was not identified. Three-
dimensional (3D) imaging estimated the volume of the
mass to be 2.4 cm3.
Subsequent fetal magnetic resonance imaging (MRI)
performed at 29 weeks’ gestation revealed a 3.0 × 2.2 ×
3.5-cm mediastinal mass located between the posterior
wall of the heart and the descending thoracic aorta,
compressing the left atrium and left lung (Figure 3).
Ultrasonography at 31 + 4 weeks’ gestation further sug-
gested that the mass was supradiaphragmatic when
paradoxical movement of the lungs and the liver was
observed during fetal breathing movements. Differential
diagnosis at this time included an atypical extralobar
pulmonary sequestration (EPS) (based on ultrasonog-
raphy), esophageal duplication cyst (based on MRI),
neuroblastoma, or, least likely, a congenital cystic adeno-
matoid malformation. Bi-weekly ultrasound scans were
performed to monitor for signs of cardiac decompensa-
tion or fetal hydrops due to the right atrial compression.
Vaginal delivery at 37 weeks’ gestation followed spon-
taneous labor, with a viable female neonate weighing
Postnatal ultrasound and computed tomography (CT)
scans (Figure 4) were performed at one day of age.
Coronal and sagittal reconstructions were obtained from
the CT scan and further showed a vessel within the mass
associated with the inferior vena cava and extending
below the diaphragm. It was not clear if this vessel
was arterial or venous. The initial neonatal course was
unremarkable with no signs of respiratory distress or
At 3 weeks of age a diagnostic right thoracoscopy
confirmed the mass to be extrapleural, in the posterior
mediastinum, posterior to the right lower lobe and
measuring 4 × 3 cm. A muscle sparing thoracotomy
was performed. The mass was found to be somewhat
adherent to the diaphragm, with a blood supply from
an infradiaphragmatic artery protruding through the
diaphragm. The mass was excised with minimal blood
loss. Histological examination of the mass was consistent
with a pulmonary sequestration. The remainder of
the patient’s hospital course was unremarkable and
the patient was discharged home on postoperative
day 2. Follow-up at 1 month revealed no long-term
Correspondence to: Dr J. D. Phillips, Division of Pediatric Surgery, Department of Surgery, 3010 Old Clinic Building, CB#7223, University
of North Carolina, School of Medicine, Chapel Hill, North Carolina 27599-7223, USA (e-mail: duncan email@example.com)
Accepted: 10 May 2005
Copyright 2006 ISUOG. Published by John Wiley & Sons, Ltd.CASE REPORT
Extralobar pulmonary sequestration
Figure 1 Coronal ultrasound image demonstrating the hyperechoic
mass with what appeared to be a subdiaphragmatic location at
21 weeks’ gestation. Arrows indicate what was thought to be the
Figure 2 Transverse image of fetal thorax at the level of the
four-chamber view of the heart, with the medial hyperechoic mass
(larger arrow) compressing the right atrium (small arrow) at
21 weeks’ gestation.
Pulmonary sequestration (PS) is a rare congenital lung
anomaly in which the pulmonary parenchyma has no
normal attachment to the tracheobronchial tree and,
typically, a systemic arterial blood supply from the aorta.
PSs may be intralobar (IPS), which remain within the
normal pulmonary parenchyma and visceral lung pleura
or extralobar (EPS), which are enclosed within their
own visceral pleura. The latter is the more common
form of PS detected prenatally, typically by second- and
third-trimester ultrasonography1. EPSs may be further
subdivided into intrathoracic forms, which are most
commonly found as a supernumerary lobe at the base of
the leftlung, and extrathoracicforms,which may beintra-
abdominal, retroperitoneal, or mediastinal masses1. To
date there have been four previous reports of an EPS in the
posterior mediastinum, all of which had gone undetected
until adulthood2–5. While IPSs rarely present in infancy
Figure 3 Fetal magnetic resonance image at 29 weeks’ gestation
showing the mass between the posterior aspect of the heart and the
descending thoracic aorta (arrow).
Figure 4 Postnatal computed tomography scan obtained at 1 day
of age demonstrating a mass (arrow) in the posterior mediastinum.
and often do not present until early adulthood with
recurrent bacterial infections, EPSs have been associated
with an increased risk of neonatal respiratory distress6.
Various surgical approaches to intrathoracic EPSs
havebeen described, including
thoracoscopy6,7. However, thoracoscopic resection of a
mediastinal EPS in an infant has not previously been
Copyright 2006 ISUOG. Published by John Wiley & Sons, Ltd.
Ultrasound Obstet Gynecol 2006; 27: 214–216.
York et al.
Although a variety of both congenital and neoplas-
tic masses may occur in the posterior mediastinum in
children, the vast majority are of neurogenic origin and
malignant, with neuroblastomas and ganglioneuromas
being the most common8. It was felt preoperatively
that neuroblastoma was a possibility in this case, but
unlikely owing to the increased echogenicity of the mass,
lack of calcifications and apparent pliability of the mass
during ultrasound evaluation, as well as normal urine
catecholamines. Close observation of prenatally detected
neuroblastomas and those detected by mass screening
has recently been advocated because of their usual excel-
lent outcome and occasional spontaneous regression9,10.
However, because malignant neuroblastoma could not be
definitely excluded preoperatively, and because of recent
reports of the prognosis of prenatally diagnosed mediasti-
nal masses, early surgical exploration was undertaken11.
Thoracoscopy was chosen because of the ability to biopsy
a potentially unresectable tumor and begin chemotherapy
promptly in the early postoperative period.
Esophageal duplication cysts, which are also commonly
found in the posterior mediastinum, are rare congenital
anomalies that were considered in the differential
diagnosis. Communication with the adjacent esophagus
is variable. However, compression causing pain or
cysts may cause hemorrhage, and the resulting debris
yields intermediate echogenicity on ultrasonography.
However through transmission of the beam is usually
seen posterior to the mass, indicating its fluid nature12.
Fetal fast MRI is a technique that allows the acquisition
of high-resolution ‘snapshot-type’ T2-weighted images in
multiple planes. Excellent depiction of the trachea, esoph-
agus and solid organs is routine13. The technique is most
commonly employed in the identification of spinal and
cranial abnormalities, especially during the second and
third trimesters, when the low position of the head in
the pelvis makes clear sonographic imaging difficult14.
Because these are T2-weighted images, masses containing
clear or proteinaceous fluid will be bright. In this case, the
location of the high signal mass adjacent to the esophagus
elicited the inclusion of duplication cyst in the differential
The typical sonographic appearance of an EPS is
a hyperechoic, solid-appearing mass, usually above
the diaphragm, or, less commonly, subdiaphragmatic.
Depending on the location of the lesion in relation
to the fetal heart, color Doppler blood flow studies
may be of value in delineating abnormal vascular
communication during the evaluation of aberrant pleural
lesions due to fetal cardiac activity. This may be
circumvented by decreasing the color Doppler gain
to reduce artifact from cardiac motion. Additional
diagnostic tests for EPS include CT and arteriograms.
An arteriogram is often used for the definitive diagnosis
of a PS, but was not performed in this case. The
postnatal CT scan (Figure 4) was useful in identifying
the aberrant blood supply initially recognized by the
prenatal power Doppler blood flow imaging. However,
neither technique was able to delineate the arterial
blood supply to the mass. Establishing a systemic
arterial supply from the aorta would have been helpful
in distinguishing the mass as a probable pulmonary
sequestration. Ruano et al. have recently shown that 3D
power Doppler can be helpful in identifying such feeder
To our knowledge this is the first reported case of a
prenatally detected posterior mediastinal EPS. Despite its
rarity, this lesion should be considered in the differential
diagnosis of fetal masses in the posterior mediastinum.
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Ultrasound Obstet Gynecol 2006; 27: 214–216.