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Year : 2004  |  Volume : 14  |  Issue : 4  |  Page : 401-404
A face of scimitar syndrome


Department of Radiodiagnosis, B. J. Medical College, Ahmedabad, Gujarat, India

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Keywords: Scimitar Syndrome - Partial anomalous pulmonary venous return, Scimitar Syndrome

How to cite this article:
Patel A M, Joshi R, Vaghela D, Shah H R, Shah U, Talsania B. A face of scimitar syndrome. Indian J Radiol Imaging 2004;14:401-4

How to cite this URL:
Patel A M, Joshi R, Vaghela D, Shah H R, Shah U, Talsania B. A face of scimitar syndrome. Indian J Radiol Imaging [serial online] 2004 [cited 2020 Jun 6];14:401-4. Available from: http://www.ijri.org/text.asp?2004/14/4/401/28681

   Introduction Top


The scimitar syndrome is a rare, complex and variable congenital malformation chiefly consisting of hypogenetic right lung, its systemic venous drainage and systemic arterial supply. The shape of the anomalous vein resembles that of a Turkish sword, Scimitar. We observed a case of scimitar syndrome involving unilobar lung in a toddler, confirmed with angiography.


   Case report Top


A two-year-old girl was referred for workup after recurrent respiratory tract infections. Supine chest radiograph revealed decreased volume in the right hemithorax with shift of the cadiomediastinal structures to the right side [Figure - 1]. Radiolucency was apparent only at the base of the right lung. Bronchoscopy did not show normal bronchial branching on the right side.

CT scan of the thorax in addition showed absence of the upper and middle pulmonary lobe parenchyma and their bronchi. The small lower lobe of the right lung was aerated by continuation of the right main bronchus. A vertically oriented draining vein was noted in the medial most part of the right lower lobe arrow in [Figure - 2]. Increased attenuation of the involved lobe was observed at lung window setting [Figure - 2].

Macroaggregated albumin static perfusion lung scan and DTPA static ventilation lung scan showed no perfusion or ventilation in the upper and middle lobe of the right lung confirming agenesia [Figure - 3]. The right lower lobe had normal aerosol distribution but photopenic perfusion defect.

Echocardiogram did not show right pulmonary veins opening into the left atrium. Barium study of the oesophagus and stomach showed rightward shift of the thoracic oesophagus but no any abnormal communication.

Flush aortogram documented fairly large aberrant artery arising from right side of the descending abdominal aorta just above the level of origin of the coeliac trunk [Figure - 4] going to base of the right lung. Venous phase confirmed broad rather vertical draining vein opening into the infradiaphragmatic inferior vena cava. [Figure - 5]. Selective injection of the anomalous artery was not done. Pulmonary arteriogram showed absence of the right pulmonary artery [Figure - 6].

Diagnosis of scimitar syndrome was confirmed. At thoracotomy, the aberrant vessels were found in the right pulmonary ligament. Histopathological examination of the excised pulmonary lobe [Figure - 7] showed three small segmental bronchi communicating normally with the lung parenchyma. Mild pulmonary congestion was present. The supplying artery was elastic-walled.


   Discussion Top


Halasz used the term scimitar in 1956 [1]. Neil named 'scimitar syndrome' in 1960 [1].

Many interesting terms are used to describe the Scimitar Syndrome (SS) as hypogenetic lung syndrome, pulmonary venolobar syndrome, epibronchial right pulmonary artery syndrome, mirror image lung syndrome, Halasz's syndrome and vena cava bronchovascular syndrome [1]. Its main elements are: 1. Hypoplasia/lobar aplasia/agenesis involving the right lung. Absence of lobar bronchus reported in literature [2] was found in our patient. Abnormal lobation including bronchial isomerism with hyparterial bronchus and unilobar lung may be present [2] [3]. Lobar agenesia (absence of parenchyma with absent corresponding bronchus) was found in our patient. Errors of segmentation may occur. 2. An anomalous right pulmonary vein connection to the systemic venous circulation either below or above the diaphragm most commonly to the inferior vena cava, occasionally into the hepatic vein, portal vein, azygos vein, coronary sinus or the right atrium [3]. The vein may drain the whole lung or part of it. 3. Partial or complete anomalous systemic arterial supply from the aorta or one of its branches to the right lung with absent or hypoplastic right pulmonary artery. Accessory diaphragm, horseshoe lung and absent inferior vena cava should also be looked for.

Persistence of early embryonal connections between the post branchial pulmonary parenchyma and the primitive dorsal aorta results in systemic arterial supply. In case of defective regression of the original splanchnic venous drainage and establishment of communication with the left atrium, the lungs will drain into the tributaries of the sinus venosus or the right atrium. The scimitar syndrome is a characteristic form of partial anomalous pulmonary venous return. Involvement of the right lung is not understood.

The scimitar syndrome is more common in women (1.4: 1) [1]. Familial occurrences have been reported [1]. The incidence is estimated to be one to three per 100000 births [3]. Manifestations of clinical symptoms in SS is dependent on the size of the resultant left to right shunt magnitude and ranges from asymptomatic to heart failure. When patient present in infancy, the symptoms are severe and associated with more anomalies. In older children it may present as recurrent respiratory infections or a heart murmur.

On plain radiograph varying degree of right lung hypoplasia and dextroposed cardiac silhouette are seen. The scimitar sign consists of a broad curved vertically oriented band along the right heart border and disappearing at the right hemidiaphragm due to the abnormal vein. It may be straight, thin or multiple [1]. This telltale sign may or may not be present on chest radiograph [2]. The absence of the scimitar sign is attributable to the very small lung, marked mediastinal shift and unfavorable orientation or small caliber of the vein [2]. Absence of the scimitar sign may be mistaken for dextrocardia or Swyer-James syndrome [1] [3]. Occasionally a wandering right pulmonary vein may create confusion before entering normally into the left atrium [1] [3].

CT establishes degree of lung underdevelopment in patients with SS and differentiates it from atelectasis, brochopulmonary sequestration and true dextrocardia. Contrast enhanced CT can of the thorax may demonstrate feeder vessels and large draining vein. Vascular engorgement as a result of perfusion of lower resistance lung circulation at systemic pressure can be reflected as increased CT attenuation [4] as in our patient [Figure - 2] Multisectional helical CT scan generate angiogram-like images to show pulmonary artery hypoplasia / absence and bronchographic images to visualized airway abnormalities [5].

Delineation of vascular supply is helpful to prevent torrential bleeding at surgery. Aortography is the more traditional investigation to document arterial supply. Differential diagnosis of systemic arterial supply to the lung includes SS, pulmonary sequestration, pulmonary arteriovenous malformation, interruption of pulmonary artery, rarely cystic adenomatoid malformation and sole or accessory arterial supply to the normal lung. The latter with coexistent infection is called pseudo-sequestration [6]. Atypical vein may not be seen sufficiently by angiography. Demonstration of the anomalous pulmonary venous return may require selective contrast injection of the feeding artery. Systemic venous drainage of the lungs can also occur in extralobar sequestration.

Echocardiography should be done to rule out associated cardiac anomalies especially atrial septal defect.

Radionuclide perfusion scan can suggest abnormal arterial supply [4]. Ventilation scan can inform about bronchial connection in a patient with SS. However in sequestration, aeration can occur through pores of Kohn or through anomalous fistulous connection. Scintigraphic screening is helpful to rule out significant vascular shunting.

Treatment for symptomatic scimitar syndrome consists of surgical repair (mobilisation) of the anomalous venous return or excision of the involved lung.

Realising the need of a rational umbrella for various congenital bronchopulmonary-vascular malformations, Pryce et al first described sequestration complex in 1974, Sade introduced the term sequestration spectrum and Clements classified them under the term 'pulmonary malinosculation spectrum'[7].

In conclusion, bronchopulmonary-vascular malformations represent erogenous and complex group of abnormalities. Although the scimitar sign is visible on chest radiograph in many patients of scimitar syndrome, additional diagnostic procedures are often necessary to confirm diagnosis and to evaluate associated abnormalities.

 
   References Top

1.Godwin J D, Tarver R D. Scimitar syndrome: Four new cases examined with CT. Radilogy 1986; 159:15-20.  Back to cited text no. 1    
2.Kiely B, Filler J, Stone S, Doyle E F. Syndrome of anomalous venous drainage of the right lung to the inferior vena cava: A review of 67 reported cases and three new cases in children. Am J Cardiol 1967; 20:102-115.  Back to cited text no. 2    
3.Gilkeson R C, Basile V, Sands M J, Hsu J T. Chest case of the day: Scimitar Syndrome. Am J Roentgenol 1997; 169:270.  Back to cited text no. 3    
4.Miyake H, Hori Y, Takeoka H, Takuma M, Kawagoe T, Mori H. systemic arterial supply to normal basal segments of the left lung: Characteristic features on chest radiography and CT. Am J Roentgenol 1998; 171:387-392.  Back to cited text no. 4    
5.Konak E, Raviv-Zilka L, Cohen R A, et al. Congenital pulmonary venolobar syndrome: Spectrum of helical CT findings with emphasis on computerized reformatting. Radiographics 2003; 23:1175-1184.  Back to cited text no. 5    
6.Felker R E, Tonkin I L D. Imaging of pulmonary sequestration: Review article. Am J Roentgenol 1990; 154:241-249.   Back to cited text no. 6    
7.Clements Warner J O, Shinebourne E A. Pulmonary Sequestration and related congenital bronchopulmonary-vascular malformations: nomenclature and classification based on anatomical and embryological considerations. Thorax 1987; 42:401-408.  Back to cited text no. 7    

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Correspondence Address:
A M Patel
42, Nirant Park Part - 1, Opp. Sun-n-step club, Thaltej, Ahmedabad-380051
India
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    Figures

[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5], [Figure - 6], [Figure - 7]

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    Introduction
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