A 17 yrs old girl presented with intralobar sequestration of lung which had arterial supply from coeliac artery and venous drainage into inferior venacava. Pre-operative thorough vascular evaluation is mandatory to prevent intra-operative and post-operative vascular catastrophy. Associated cardiovascular anomaly also pose increased risk to the surgery.

Introduction
Bronchopulmonary sequestration is a rare congenital malformation, consist of non-functioning lung segment which has no communication with tracheobronchial tree and has anomalous arterial and venous supply from systemic vessel. Vessel can be single or multiple. It is associated with congenital anomalies in 60% of cases.

A 17 year old girl underwent right lower lobectomy for symptomatic intralobar sequestration (ILS). She had anomalous arterial supply to ILS from coeliac artery and venous drainage to IVC.

Careful preoperative evaluation of anomalous blood supply and congenital anomalies is necessary to prevent intra and postoperative surgical complications.

Case Report
A 17 year old girl presented with recurrent right basal pneumonia treated with course of antibiotics over many occasions at peripheral private clinic. X-ray chest and MRI (Fig. 1) showed mass in right lower lobe with cystic changes. With high index of suspicion of ILS, MRI angio was done. It revealed cystic lesion in right lower lobe parenchyma with anomalous arterial supply from coeliac artery (Fig. 2). It failed to delineate venous drainage. With these findings diagnosis of ILS was made.

Left side double lumen endotracheal tube was used for selective ventilation to achieve right side mini-thoracotomy and right lower lobectomy. The anomalous artery from coeliac branch was found to be entering into sequestration via oesophageal hiatus and large size vein draining into IVC was dissected and ligated (Fig. 3). Right lower lobectomy was performed.

Post-operative period was uneventful. The histopathology confirmed diagnosis of ILS.

Fig. 1 : MRI of the chest showing intralobar sequestration.	Fig. 2 : Anomalous arterial supply from coeliac artery.
Fig. 3 : Arrow showing anomalous vein from ILS draining into IVC.

Discussion
Pulmonary sequestration (PS) is a spectrum of congenital lung anomalies in which there is an abnormal connection of one or more of the four major components of lung tissue (i.e. the airway, lung parenchyma, arterial supply and venous drainage). Extralobular pulmonary sequestration (ELS) has distinct pleural covering maintaining complete anatomical separation of the mass from adjacent normal lung tissue. In contrast, intralobar sequestration (ILS) are masses of lung parenchyma that are contiguous with the adjacent normal lung. The theory most widely accepted suggest that PS result from formation of an accessory bud caudal to the normal lung bud.1,2 PS is the second most common congenital lung anomaly with estimated incidence of 0.15-1.8%. This figure may be underestimate as case reports exist of adults developing complication of PS and small lesions may remain asymptomatic.3

ELS may be identified antenatally during screening of a baby for another congenital anomaly.4,5 One quarter of babies present shortly after birth with respiratory distress or feeding difficulties. More than 60% of patients with ELS have co-existent congenital anomalies. Congenital diaphragmatic hernia is the most common co-existing anomaly affecting around 16%. About 25% will have another congenital lung abnormality such as hypoplasia, congenital cystic adenomatous malformation (CCAM), congenital lobar emphysema or bronchogenic cyst. Other associations include pectus excavatum, pericardial defect and cysts trancus arteriosus, total anomalous pulmonary venous drainage.6

ILS unless detected during an antenatal ultrasound they rarely cause problem before the age of 2 yrs. Presentation is usually the result of chronic or recurrent pneumonia. A small number of patients present with high output cardiac failure, haemoptysis or massive intrathoracic bleeding.7 The arterial supply to ILS comes from descending thoracic (73%) and abdominal aorta (20%). Venous drainage of more than 95% of ILS is directly into the pulmonary veins.

A high index of suspicion is required in every child presenting with symptoms such as recurrent infections, respiratory distress or congenital cardiac failure without any obvious cause. Most ILS present as a well defined triangular shape mass with its long axis pointing medially and posterior in the lung base.

Ultrasound is recommended as the first diagnostic modality for evaluating PS which present as a hyperechoic chest mass. Doppler ultrasound detects feeding arteries and draining veins confirming the diagnosis of PS.8 Computed tomography (CT) demonstrate the parenchymal abnormalities associated with PS but is inconsistent at identifying the aberrant arterial supply and venous drainage.8 Magnetic resonance imaging demonstrate parenchymal lung changes as well as anatomic localization of the systemic arterial supply and venous drainage of a PS.9 When non-invasive imaging fails, conventional angiography still has a place in evaluating PS.

Treatment of symptomatic PS consist of surgical resection of anomaly once infection is under control. Resection provides absolute tissue diagnosis and remains treatment of choice. Resection of ILS almost always involves a lobectomy. In case of ELS, sequestrectomy is possible. For both lesions, the crucial part of surgical procedure is identification and control of aberrant vascular supply.

Formal thoracotomy remains the standard method for resection, although thoracoscopic surgery is being advocated by some.10,11 Advocates of this approach argue that the small incision may reduce the risk of musculoskeletal deformity including chest wall asymmetry, scoliosis, rib fusion and winging of the scapula reported after posterolateral thoracotomy.

When cardiac decompression is the result of a PS, occlusion of feeding vessel under radiographic control is possible either as definitive treatment or in combination with resection.12,13

In our case, 4 distinct uncommon presentations were, age of detection - 16 years, aberrant artery was from coeliac (only 20% have blood supply from abdominal aorta) and venous drainage was into IVC (while normally 95% of ILS drain into pulmonary vein) and there was no associated congenital malformation.

Intrathoracic segment of aberrant artery from coeliac axis was very short. It could slip below diaphragm and cause catastrophic bleeding which remain concealed for long time before detection.

Venous drainage of entire lung could be through anomalous vein and ligation of this could cause venous gangrene of lung may land up into emergency pneumonectomy. There has been a case report of salvage of remaining lung in such anomaly by implanting vein directly into the atrium.

Coronary source of arterial supply is very rare and can cause Steel syndrome and require angiography as preoperative search.

References

1. Nicollette LA, Kosloske AM, Barlow SA, Murphy S. Intrapulmonary sequestration - a clinical and pathological spectrum. J Paediatr Surg 1993; 28 : 802-5.
2. Langstone C. New concepts in the pathology of congenital lung malformations. Semin Paediatr Surg 2003; 12 : 17-37.
3. Carter R. Pulmonary sequestration (collective review). Ann Thoracic Surg 1969; 7 : 68-88.
4. DeParedes CG, Pierce WS, Johnson DG. Pulmonary sequestration in infants and children : a 20 year experience and review of the literature. J Paediatr Surg 1970; 5 : 136-47.
5. Stocker JT. Sequestration of the lung. Semin Diagn Pathol 1986; 3 : 106-21.
6. Buntain WL, Wolley MM, Mahon GH, et al. Pulmonary sequestration in children, a twenty five year experience. Surg 1977; 81 : 413-20.
7. Laurin S, Aransons, Schuller H, Hennkson H. Spontaneous hemothorax from bronchopulmonary sequestration, unusual angiographic and pathologic - anatomic finding. Paeditr Radiol 1980; 10 : 54.
8. Kezoe J, Murayame S, Godwin JQ, et al. Bronchopulmonary sequestration CT assessment. Radiology 1990; 176 : 375-79.
9. Kouchik K, Yoshida M, Matsunga T, et al. Intralobar bronchopulmonary sequestration evaluated by contrast enhanced three dimensional MR angiography. Paediatr Radiol 2000; 30 : 774-75.
10. Mezzeti M, Del Agnola CA, Bedoni M, et al. Video assisted thoracoscopic resection of pulmonary sequestration in an infant. Ann Thorac Surg 1996; 6 : 1836-37.
11. Guer S, Schart A, Ure BM. Thoracoscopic resection of extralobar sequestration in neonatal. J Paediatr Surg 2002; 37 : 1629-31.
12. Park ST, Yoon CH, Sung KB, et al. Pulmonary sequestration in a newborn infant with arterial embolisation. J Vasc Intern Radiol 1998; 9 : 648-50.
13. Curros F, Chrat V, Edmond S, et al. A role of embolisation in the treatment of bronchopulmonary sequestration. Radiol 2000; 30 : 769-73. Urol 2001; 36 : 784-91.