IMAGING CASE REPORT Extralobar Sequestration

TE Herman and MJ Siegel Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Missouri, USA

Journal of Perinatology (2009) 29, 524–525; doi:10.1038/jp.2008.249 The arterial blood supply of extralobar sequestrations arises from either the thoracic or the abdominal aorta in 80% of cases, Case presentation with the aortic branches arising from the splenic artery, gastric A 3660 g male infant was born by elective Cesarean section at 39 artery, subclavian artery or intercostal arteries in 15% and from the weeks to a gravida 4, para 3 to 4 mother. The pregnancy had been pulmonary artery in 5%.4 The venous drainage of ELS is usually complicated by a fetal sonogram at 34-weeks gestation showing a through the systemic circulation into the hemiazygos veins, azygos right chest mass, believed to be a type III congenital cystic adenomatoid malformation or a congenital pulmonary airway malformation. Polyhydramnios was present and the infant remained in a transverse lying position. At delivery, the baby had Apgars of seven at 1 min and nine at 5 min. He was stable on room air and was not in respiratory distress. A chest radiograph (Figure 1) and chest CT scan (Figure 2) were obtained.

Denouement and discussion The CT scan showed a soft tissue mass with a vascular supply from the thoracic aorta and venous drainage probably into the hemiazygos vein, creating a vascular stalk or pedicle for the mass. At surgery, the mass was identified and recognized as an extralobar sequestration completely separate from the normal trilobed right lobe. The vascular pedicle was isolated showing an artery arising from the thoracic aorta. The venous communication was seen to drain into the hemiazygos vein. These vessels were ligated and the mass easily removed. The pathological specimen showed normal lung tissue with benign bronchiolar epithelium. Pulmonary sequestrations, first described in 1946 by Pryce1, are a mass of pulmonary tissue sequestered or separated from the normal bronchial connections and with an aberrant blood supply. Classically, a sequestration is thus carried out both from the bronchial tree and the pulmonary artery circulation.1 Sequestrations are believed to arise from supernumerary lung buds that arise from the primitive foregut in about the fifth week of gestation.2,3 Two types are described: as intralobar sequestration and extralobar sequestration (ELS). Extralobar sequestration comprises B25% of all sequestrations and is covered by a separate pleural investment.4 Intralobar sequestration shares a pleural investment with the ipsilateral lung, which may become aerated through the pores of Kohn. The ELS are nonaerated masses.

Correspondence: Dr TE Herman, Mallinckrodt Institute of Radiology, St Louis Children’s Figure 1 (a) Frontal chest and (b) lateral chest radiographs. A soft tissue mass Hospital, Washington University School of Medicine, 510 South Kingshighway Blvd., St Louis, (white arrows) is present posterolaterally in the right hemithrorax causing Missouri, USA. mediastinal shift to the right. An umbilical venous catheter (black arrow) is in E-mail: [email protected] place ending in the right atrium. Extralobar sequestration TE Herman and MJ Siegel 525

Figure 2 (a) Thin transaxial CT scan at level of mid thorax, thin slice, (b) transaxial CT scan at approximately the same level, reformatted in a thicker slice and (c) Coronal reformatted CT scan image through the descending thoracic aorta. A low-density soft tissue mass is present posterolaterally with arterial supply (arrow) arising from the thoracic aorta (A). Anterior to the anomalous artery is a larger diameter-draining vein (V) that communicates with the hemiazygos vein (HA). veins, inferior vena cava or portal vein.2 Approximately 65% of ELS The patient reported herein had a large ELS with typical arterial are located on the left side and 70% of these are located between supply and venous drainage, as seen in an asymptomatic male the left lower lobe and the diaphragm.2 Approximately 10% of ELS infant. Surgical resection, as carried out in this patient, is the are located below the diaphragm in the left suprarenal treatment of choice. retroperitoneum.5 These abdominal retroperitoneal ELS need to be differentiated from other suprarenal masses, especially neuroblastoma.5 Approximately 25% of ELS have some areas of References 6 type II congenital cystic adenomatoid malformation within them. 1 John PR, Beasley SW, Mayne V. Pulmonary sequestration and related congenital Congenital cystic adenomatoid malformation, also known as disorders; clinicoradiological review of 41 cases. Pediatr Radidol 1989; 20:4–9. congenital pulmonary airway malformations , are hamartomatous 2 Rosado de Christenson ML, Frazier AA, Stocker JT, Templeton PA. Extralobar malformations of pulmonary mesenchymal elements classified by sequestration: radiologic–pathologic correlation. RadioGraphics 1993; 13: 425–441. Stocker by histological and macroscopic characteristics into three 3 Morin C, Filiatrault D, Russo P. Pulmonary sequestration with histologic changes of cystic adenomatoid malformation. Pediatr Radiol 1989; 19: 130–132. major types. Type I contains large cysts, larger than 2 cm in 4 Felker RE, Tonkin ILD. Imaging of pulmonary sequestration. AJR 1990; 154: diameter, type II contains cysts varying between 1 and 2 cm and 241–249. 3 type III contains microscopic cysts. Thirty percent of ELS occur in 5 Laje P, Martinez-Ferro M, Grisoni E, Dudgeon D. Intraabdominal pulmonary association with Bochdalek hernias.7 sequestration. A case series and review of the literature. J Pediatr Surg 2006; 41: Increasingly, ELS are being discovered by in utero sonography. 1309–1312. A significant number (35 to 70%) of inutero detected ELS 6 Benya EC, Bulas DI, Selby DM, Rosenbaum KN. Cystic sonographic appearance of 8,9 extralobar pulmonary sequestration. Pediatr Radiol 1993; 23: 605–607. spontaneously regress during pregnancy. Most cases of 7 Sade RM, Clouse M, Ellis FH. The spectrum of pulmonary sequestration. Annals postnatally detected ELS are symptomatic, and are usually detected Thoracic Surgery 1974; 18: 644–655. within the first 6 months of life.2 At birth, presenting signs of ELS 8 Kitano Y, Matsuoka K, Honna T, Kuroda T, Morikawa N, Hayashi S et al. Venous include nonimmune hydrops and large pleural effusions, believed arterialization in extralobar pulmonary sequestration associated with fetal hydrops. to be because of venous obstruction from the sequestration J Pediatr Surg 2006; 41: 490–494. 8 9 Samuel M, Burge DM. Management of antenatally diagnosed pulmonary sequestration inutero. Later symptoms include pneumonia, cough, cyanosis, associated with congenital cystic adenomatoid malformation. Thorax 1999; 54: 9 recurrent infection and high output congestive heart failure. There 701–706. 10 is a 3:1 to 4:1 male-to-female ratio among patients with ELS. 10 Stocker JT. Sequestration of the lung. Seminars Diagnostic Pathol 1986; 3: 106–121.

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