A 2-day-old, full-term neonate diagnosed with a cystic lesion of the left lung during antenatal ultrasound with subsequent magnetic resonance imaging for characterization was referred for surgical consultation. The prenatal magnetic resonance image scan was remarkable for abnormal increased T2 signal of the left upper lobe (arrow, Fig 1) as compared with the remainder of the lungs. The differential diagnosis included bronchopulmonary sequestration versus cystic adenomatoid malformation. The neonate underwent a 16-slice multi-detector computed tomographic angiogram with volume rendered imaging (Fig 2) that revealed a hypervascular mass (3.7 × 2.6 × 2.1 cm) in the anterior aspect of the left lung base with the appearance of normal lung parenchyma. Both the arterial supply, arising from the left subclavian artery immediately proximal to the origin of a dilated left internal mammary artery, and venous drainage exiting the left innominate vein were prominent vessels running parallel to each other (arrow, Fig 2). Findings in the left lung base were compatible with an extralobar sequestration. The patient underwent a muscle-sparing left thoracotomy. Intraoperative findings included the aforementioned sequestered lung segment, adjacent to the inferior lingular segment, which was attached by a solitary vascular pedicle to the chest wall. Division of this attachment allowed for subsequent excision.Fig 2View Large Image Figure ViewerDownload (PPT) Pulmonary sequestration is an uncommon mass comprising 6% of all congenital pulmonary malformations. This consists of nonfunctioning, noncommunicating, primitive lung tissue with its blood supply originating from an anomalous systemic artery [1Laberge J.M. Puligandla P. Flageole H. Asymptomatic congenital lung malformations.Semin Pediatr Surg. 2005; 14: 16-33Abstract Full Text Full Text PDF PubMed Scopus (233) Google Scholar]. Extralobar sequestration specifically forms less than 10% of all sequestrations, with the majority located in the left chest between the hemidiaphragm and the left lower lobe. Due to the propensity for respiratory, hemorrhagic, and malignant complications, management consists of complete surgical excision [2Shanmugan G. MacArthur K. Pollack J.C. Congenital lung malformations—antenatal and postnatal evaluation and management.Eur J Cardiothorac Surg. 2005; 27: 45-52Crossref PubMed Scopus (95) Google Scholar]. In this particular case, we operated early due to an extenuating psychosocial circumstance (ie, the child and family were at extremely high risk for being lost to follow-up) [1Laberge J.M. Puligandla P. Flageole H. Asymptomatic congenital lung malformations.Semin Pediatr Surg. 2005; 14: 16-33Abstract Full Text Full Text PDF PubMed Scopus (233) Google Scholar], and the patient was physiologically mature enough to undergo the procedure. Although the precise timing of surgical intervention remains somewhat controversial, the consensus recommendations in the literature are that patients should undergo surgery sometime during infancy; this approach seems to balance the issues of infectious risk, whereas simultaneously optimizing developmental maturation of the child [1Laberge J.M. Puligandla P. Flageole H. Asymptomatic congenital lung malformations.Semin Pediatr Surg. 2005; 14: 16-33Abstract Full Text Full Text PDF PubMed Scopus (233) Google Scholar, 2Shanmugan G. MacArthur K. Pollack J.C. Congenital lung malformations—antenatal and postnatal evaluation and management.Eur J Cardiothorac Surg. 2005; 27: 45-52Crossref PubMed Scopus (95) Google Scholar].