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J Thorac Cardiovasc Surg 2006;132:185-187
© 2006 The American Association for Thoracic Surgery
Brief Communication |
a Department of Surgery, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan
b Department of Pathology, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan
Received for publication December 6, 2005; accepted for publication January 13, 2006. * Address for reprints: Hong-Shiee Lai, MD, PhD, Department of Surgery, National Taiwan University Hospital, No. 7, Chung-Shan South Road, Taipei, Taiwan. (Email: hslai{at}ha.mc.ntu.edu.tw).
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Pulmonary sequestration (PS) is a condition that may remain asymptomatic and never be diagnosed. Extralobar sequestration (ELS) accounts for 25% of all sequestrations and may present with respiratory distress, feeding difficulties, or congestive heart failure in the first 6 months of life. It is usually identified by routine sonography when screening for other congenital anomalies and may occur in the thoracic cavity or above or below the diaphragm.
2
However, it is rarely reported in the mediastinum, especially at the neonatal stage. We now describe an asymptomatic newborn with ELS in the posterior mediastinum.
Clinical Summary
A male fetus was diagnosed with a hyperechogenic mass in the retroperitoneal or mediastinal space by antenatal ultrasonography during routine prenatal examinations at 28 weeks of gestational age in a gravida 2, para 2 woman (Figure 1, A). The mother had no family history of congenital abnormalities, and her pregnancy was uneventful. The biophysical profile of the fetus was normal, and he was born by spontaneous vaginal delivery at 37 weeks of gestation. His birth weight was 2950 g, and his APGAR score was 9 at 1 minute and 10 at 5 minutes after delivery. No other congenital anomalies were noted on postnatal physical examination, which disclosed no abnormality.
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Through a transverse laparotomy, no diaphragmatic hernia or mass lesion was seen in the peritoneal cavity. The left hemidiaphragm and the mediastinal surface of the medial parietal pleura were then opened. A pyramid-shaped, smooth, soft, well-encapsulated mass, measuring 2 x 3 x 3 cm, was found attached to the descending aorta and superiorly to the diaphragm (Figure 2, A, B). One short feeding artery originating from the aorta was identified and then ligated and divided before excision of the mass. The cut surface of the mass was spongy-like (Figure 2, C).
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Discussion
Approximately 90% of ELS has been reported to be in the left thorax, between the lower lobe of the lung and the diaphragm, especially involving the posterior costophrenic sulcus.
1
Associated congenital abnormalities are common in more than 60% of patients with ELS. Only 8% of extralobar sequestrations are intra-abdominal or retroperitoneal, which are sometimes associated with diaphragmatic hernia and are diagnosed in the first decade of life. With routine prenatal ultrasonographic examination, ELS could possibly be detected prenatally with increasing frequency.
Only 3 cases of extralobar PS in the posterior mediastinum have been reported,
3-5
but none of these were at the lower posterior mediastinum. These patients included 2 women, aged 45 and 48 years, and a man aged 65 years, with ELS bounded anteriorly by the pericardium and posteriorly by the bodies of the thoracic vertebrae. In contrast, our patient was identified at the neonatal stage with ELS at the lower posterior mediastinum.
The definitive diagnosis was not reached before surgery in this patient. A preoperative diagnosis of PS and its supplying artery, especially the identification of the systemic artery, is important in preventing injury to the blood supply of the normal lung. Although angiography is somewhat risky for infants and young children, it might be required in patients in whom there is a failure to demonstrate the anomalous vessel by magnetic resonance angiography because of the small size of the artery or an unfavorable orientation in relation to the scanning plane. The unusual location and failure of angiographic image studies makes the preoperative diagnosis of ELS difficult. Therefore, exploratory surgery is indicated, even in an infant, to exclude other diagnoses.
Conclusion
We present a case of a neonate with ELS in an unusual location without any associated congenital abnormalities. It must be emphasized that PS is one of the differential diagnoses for asymptomatic mediastinal mass in a neonate. A thorough and comprehensive combination of imaging approaches should be used, followed by a pathologic examination of the congenital anomaly to establish a definitive diagnosis.
References
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). D, Diaphragm; L, lung; M, mass; PP, parietal pleura.