Ann Thorac Surg 2006;82:327-329
© 2006 The Society of Thoracic Surgeons
Case report
Successful Surgical Resection of Intrapericardial Extralobar Pulmonary Sequestration With Congenital Pulmonary Adenomatoid Malformation Type II
Mudaffer Al-Mudaffer, MBChB, MRCPI
a
,
Clare Brenner, FRCR
b
,
Michael McDermott, FRCPath
c
,
Martin White, MD, FRCPI
d
,
Alfred E. Wood, FRCSI
e
,
Colin J. McMahon, MRCP(UK), FAAP
a
,
*
a Department of Pediatric Cardiology, Crumlin, Dublin, Ireland
b Department of Radiology, Crumlin, Dublin, Ireland
c Department of Pathology, Crumlin, Dublin, Ireland
d Department of Neonatology, Crumlin, Dublin, Ireland
e Department of Cardiothoracic Surgery, Our Lady's Hospital for Sick Children, Crumlin, Dublin, Ireland
Accepted for publication August 25, 2005.
* Address correspondence to Dr McMahon, Department of Pediatric Cardiology, Our Lady's Hospital for Sick Children, Crumlin, Dublin, 12 Ireland (Email: colin.mcmahon{at}olhsc.ie).
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Abstract
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We report a 7-day-old boy referred to our institution with tachypnea and cardiomegaly who was discovered to have an intrapericardial extra-lobar pulmonary sequestration containing a cystic pulmonary adenomatoid malformation type II. He underwent successful surgical resection of the intrapericardial mass, which we believe represents the first reported case of this rare entity.
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Introduction
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Intrapericardial extra-lobar pulmonary sequestration (ELPS) represents a very rare occurrence with only a few isolated cases reported in the literature. Extra-lobar pulmonary sequestration in combination with congenital pulmonary adenomatoid malformation is a well-recognized association by contrast.
A baby boy was referred to our institution for evaluation of cardiomegaly and tachypnea at 7 days of age. The baby had been born at 39 weeks gestation by vacuum-assisted delivery due to failure to progress. His birth weight was 3.5 kg, and his Apgar scores were 6 at 1 minute and 7 at 5 minutes. The baby was pale at birth and had secondary apnea develop, which required bag and mask ventilation for 30 seconds. He was noted to have muffled heart sounds and a displaced apex beat. A chest roentgenogram showed moderate cardiomegaly, bilateral pneumothoraxes which were initially aspirated, and then bilateral chest drains that were inserted and remained in situ for 2 days prior to removal.
Transthoracic ultrasound and echocardiography revealed a moderate-sized pericardial effusion with a large mass within the pericardial sac, which seemed to originate from around the aortic arch with an arterial connection from the base of the innominate artery. The mass was noted to pulsate in unison with the cardiac mass. Alpha-feto-protein level was normal. Axial computed tomography with sagittal reformats (post-intravenous contrast [Siemens Somatom Duo, Berlin, Germany]) demonstrated an enhancing mass in the anterior mediastinum in association with pericardial effusion (Figs 1A, B). The boy underwent cardiac catheterization, which confirmed the presence of a vessel arising from the aorta at the base of the innominate artery, but the cardiac anatomy was otherwise normal (Fig 2). A percutaneous biopsy of the anterior mediastinal mass was then performed.
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Fig 1. (A) Axial post-contrast computed tomographic (CT) scan at the levels of the aortic arch demonstrating an enhanced mass in the anterior mediastinum. The thymus was compressed posterolaterally to the left. A pericardial effusion was more apparent inferiorly. (B) Sagittal reformatted CT scan shows the anterior position of the mass correlated with the angiogram.
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Fig 2. Aortography demonstrates the feeding vessel arising from the aorta at the base of the innominate artery that supplies the mediastinal and intrapericardial mass.
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Surgical excision at 11 days of age was performed through a median sternotomy. This consisted of a thymectomy after opening the pericardium, and ligation and division of the pedicular vessels and complete resection of the mass, which seemed to extend from the aorta to the superior vena cava and the superior mediastinum. The pericardium was closed, a chest drain was inserted, and the sternum and skin were closed. The postoperative course was complicated by an elevated left hemidiaphragm secondary to left phrenic nerve paresis. On most recent follow-up the patient was 6 months of age and had fully recovered. He has persistent feeding problems including gastroesophageal reflux, but he continues to thrive.
Initial tru-cut biopsy demonstrated the presence of mature lung tissue only. Gross examination of the subsequently resected mass revealed a polypoid segment of lung parenchyma (weighing 40 g and measuring 6.9 x 5.7 x 1.8 cm) rising from a 6-mm stalk (Fig 3). Histopathologic evaluation revealed the mass to be an ELPS with associated congenital pulmonary adenomatoid malformation type II (Fig 4).
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Fig 3. Gross examination revealed a polypoid segment of lung parenchyma (weighing 40 g and measuring 6.9 x 5.7 x 1.8 cm) rising from a 6-mm stalk.
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Fig 4. Histologic sections of the resected mass show mature pulmonary tissue with crowded cystic areas lined by ciliated columnar epithelium, consistent with congenital pulmonary adenomatoid malformation type II.
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Comment
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Extra-lobar pulmonary sequestration arising within the pericardial space is rare with only five previously reported cases [1–3]. However, there is a well-established association between ELPS and congenital pulmonary adenomatoid malformation (CPAM), previously referred to as congenital cystic adenomatoid malformation with many ELPSs containing areas that were histologically indistinguishable from CPAM [4]. Despite their frequent occurrence in other sites, we believe that ELPS with CPAM has not been previously reported in the pericardium. Of note, ELPS has been previously described in association with bronchogenic cyst within the pericardial space [5].
Pulmonary sequestration is classified as ELPS in which a mass of the lung parenchyma possesses a distinct pleural covering separate from the tracheobronchial tree with an arterial blood supply from the systemic vasculature or intralobar (ILS), in which the mass of lung parenchyma is contiguous with the adjacent normal lung [3]. These represent as much as 6% of all pulmonary malformations. The ratio of intralobar to ELPS is reported to be 2 or 3 to 1, with the majority of cases of ELPS presenting in the first 6 months of life with respiratory distress or feeding difficulties as in the case of our patient. There have been several reports of intrapericardial ELPS alone or in combination with bronchogenic cysts, but the combination with CPAM in this location is unusual [1–4]. Unlike intralobar, ELPS has a strong association with cardiac and diaphragmatic anomalies. Combined imaging modalities used in the diagnosis include ultrasound, angiography, computed tomographic thorax, and magnetic resonance imaging. Increasingly magnetic resonance imaging will probably supersede computed tomography and angiography as the investigation of choice [6]. Fetal echocardiography has also been reported in diagnosing this condition.
As many as 50% of ELPS cases are associated with CPAM type II, which has prompted some investigators to propose a common embryologic cause with the formation of an abnormal accessory bud from the normal lung around week 5 of gestation, presumably as a result of abnormal signaling between the lung mesenchyme and the penetrating airway [1, 7]. Evidence to support this hypothesis stems from a study showing in lung organ cultures that endoderm migrate out of the splanchnic mesoderm toward fibroblast growth factor 10, whereas fibroblast growth factor 7 has been implicated in the pathogenesis of CPAM [1, 7].
Surgical resections of ELPS and CPAM type II have been well described and advocated, even in the absence of symptoms, given the potential for such tissue to degenerate with rhabdomyomatous dysgenesis and rhabdomyosarcomas reported in ELPS and bronchioloalveolar carcinoma within CPAM. Endovascular embolization of ELPS has also been recently described [8]. Given the intrapericardial involvement in this patient, potential interference with ventricular function would also justify surgical removal. Surgical resection through a median sternotomy can be safely performed as in this case without the need for cardiopulmonary bypass on stand-by. Despite its rarity, this report serves to highlight that the intrapericardial masses may represent ELPS in association with CPAM type II.
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References
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Abstract
Introduction
