|
Fig.
2A:
Chest radiograph shows dextrocardia, a hyperlucent
right lung, and small right pulmonary artery.
A small, abnormal
draining vein is seen overlying the right lower lobe (arrow).
|
Fig.2B
Fig.2C
|
|
Fig. 2D
|
Fig.2E
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Fig.2F
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Roentgen Ray 1997
uhrad.com - Chest Imaging Case of the Day
Case #2
by: Robert Gilkeson, M.D.
Mark Sands, M.D. Diagnosis: Scimitar Syndrome.
Fig. 2F: A contrasted chest CT with soft tissue
windows show a small right pulmonary artery (2B),
and abnormal draining vein entering the IVC (2C, 2D) (arrows.) The lung
windows show a small, bilobed
right lung (2E), an abnormal bronchial branching patternE, and
bronchiectasis of the upper lobe (2F). Discussion: The patient is a 53
year old patient with a history of radiation treatment for Stage I breast
cancer, who presented to her physician with the history of persistent
cough and sputum production. Her clinical history included the diagnosis
of "dextrocardia" and chronic "URI symptoms." A chest
radiograph (Fig. 2A) confirmed shift of the mediastinal structures to the
right and a small right hemithorax. Closer evaluation revealed a small
right pulmonary hilum, a relatively hyperlucent right lung, absence of
the right minor fissure, and a tubular opacity within the right lower
lobe. A spiral CT of the thorax (Fig. 2B-2E) confirmed the mediastinal
shift, the bilobed right lung and an anomalous bronchial branching
pattern in the right lung. The tubular opacity was found to represent an
abnormal draining vein from the right lower lobe terminating in the
supradiaphragmatic IVC. Evaluation of the right upper lobe showed cystic
bronchiectasis(Fig. 2F).
The "scimitar
syndrome" is a rare complex of disorders which have
been variously called pulmonary venolobar syndrome
[1], hypogenetic lung syndrome, and right pulmonary artery syndrome.
First described by Cooper and Chassinat in 1836, Halasz first coined the
term "scimitar syndrome" to refer to the appearance of the
abnormal draining vein, which he likened to the shape of a Turkish sword.
[2] The classic components of the scimitar syndrome is abnormal venous
drainage of the affected lung, dextrocardia, and systemic arterial supply
to the affected lung.
[3] The right lung is affected in the vast majority of cases, and there
is a slight female predominance, with scattered reports of familial
cases. Incidence is estimated to be between 1-3/100,000 births
[4] Symptoms can vary widely, and while many patients are asymptomatic,
some patients, as seen in this case, suffer from repeated pulmonary
infections. The constant feature of the scimitar syndrome is the abnormal
draining vein, and it is usually seen draining a part or all of the
involved hypogenetic lung. Its course is variable, and while it usually
drains into the infradiaphragmatic IVC, drainage into the right atrium,
hepatic veins, portal or azygous vein has been reported
[4]. While this abnormal draining vein does represent a left to right
shunt, the shunt fraction is generally less than 2:1. In a study of over
100 such patients, the pulmonary artery pressure was normal in 85% and
only slightly greater than normal in the remaining patients.[4] In some
cases, ligation or coil embolization of the draining vein has been
effective in symptomatic patients
.[5] There are reports of pulmonary venous anomalies that can mimic the
scimitar vein, most commonly a "wandering" pulmonary vein that
eventually drains into the left atrium.
[6] Along with the abnormal scimitar vein, there is a spectrum of
abnormalities of the tracheobronchial tree. There is often abnormal
lobation, and the right lung may be bi- or unilobed. The right bronchus
is often hyparterial and abnormally long. There are associated
abnormalities of the trachea, and tracheal stenoses and diverticula are
common. While the incidence of bronchiectasis in one series was 5%, it is
frequently seen in the symptomatic population. Abnormal systemic arterial
supply to the lung is common, though it is often difficult to demonstate.
[7] There is a 25% incidence of congenital heart disease in these
patients. Secundum type ASDs are the most common abnormality, and
tetralogy of Fallot, ventricular septal defects, and patent ductus
arteriosus
[4] have been reported. Accessory or bilobed hemidiaphragm are also
associated with the scimitar syndrome. It is important to recognize that
the scimitar syndrome can mimic other conditions such as hypoplastic lung
and Swyer James, and that identification of the scimitar vein is not
possible in all cases. While angiography has been traditionally used for
definitive diagnosis, noninvasive imaging with CT scan and cine MRI [8]
may noninvasively identify the pertinent vascular structures that define
this syndrome. References:
1. Tomsick TA, Mosener SE, Smith WL Jr. The congenital venolobar syndrome
in three successive generations. J Assoc Canada Radiol 1976;27:196-199.
2. Halasz NA, Halloran KH, Liebow AA. Bronchial and arterial anomalies with
drainage
of the right lung into the inferior vena cava.Circulation
1956;14:826-846.
3. Partridge JB, Osborne, JM, Slaughter RE. Scimitar etcetera-the
dysmorphic right lung.
Clinical Rad 1988;39(1):11-9.
4. Dupuis, C, Charaf, LAC et al. The "adult" form of the
scimitar syndrome. Amer J Cardiol.
70: 502-507,1992.
5. Schramel FM, Westerman CJ et al. The scimitar syndrome:clinical
spectrum and sugical
treatment. European Respiratory J 1995;8(2):196-201.
6. Kanemoto N Sugiyama T et al.
A case with pseudo-scimitar syndrome:"scimitar sign"
with normal pulmonary venous drainage. Japanese Circulation Journal 1987;
51(6):642-646.
7. Godwin JD and Tarver RD Scimitar syndrome: four new cases examined
with CT.
Radiology;1986:159:15-20.
8. Baran R. Kir A, et al. Scimitar syndrome:confirmation of diagnosis by
a noninvasive technique
(MRI). European Radiology 1996; 6(1):92-4, 1996.
Return to Day #3
Submitted by:
Robert C. Gilkeson, M.D.
Mark Sands, M.D.
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