Congenital Malformations of the Lung

Keith T. Oldham and Kathleen M. Dominguez

AbstractCongenital lung malformations are uncommonbut extraordinarily diverse in their presenta-tion. Potential consequences may be life-threatening; therefore, an understanding ofthe diagnosis and treatment of these anomaliesis important to all physicians and surgeons whocare for infants and children. These lesionsvary from asymptomatic to immediately life-threatening in nature and may present antena-tally or well into adulthood. Lung developmentand anatomy are important fundamentals in thediscussion of these malformations and aide inunderstanding the pathophysiology whichoccurs. The most common congenitalmalformations include congenital pulmonaryairway malformations, pulmonary sequestra-tions, lobar emphysema, and bronchogeniccysts.

KeywordsCongenital pulmonary airway malformations •Congenital cystic adenomatoid

malformations •Congenital lobar emphysema •Pulmonary sequestration • Bronchogenic cyst

ContentsIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Embryology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Anatomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Congenital Pulmonary Airway Malformations/Congenital Cystic AdenomatoidMalformations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Pathology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Radiographic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Clinical Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Fetal Therapy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Postnatal Therapy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Pulmonary Sequestrations . . . . . . . . . . . . . . . . . . . . . . . . . . 8Pathology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Congenital Lobar Emphysema . . . . . . . . . . . . . . . . . . . . . 11Pathology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Presentation and Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Clinical Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Bronchogenic Cysts and CongenitalLung Cysts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Pathology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

K.T. Oldham (*)Division of Pediatric Surgery, Medical College ofWisconsin, Children’s Hospital of Wisconsin, Children’sCorporate Center, Milwaukee, WI, USAe-mail: koldham@chw.org

K.M. DominguezPediatric Surgery, Marshfield Clinic, Marshfield, WI, USAe-mail: dominguez.kathleen@marshfieldclinic.org

# Springer-Verlag GmbH Germany 2017P. Puri (ed.), Pediatric Surgery,DOI 10.1007/978-3-642-38482-0_56-1

1

Presentation and Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . 14

Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Pulmonary Hypoplasia, Aplasia, and Agenesis . . . 15

Lung Surgery in Newborns . . . . . . . . . . . . . . . . . . . . . . . . . 17

Complications and Long-Term Outcomes . . . . . . . . . 18

Conclusions and Future Directions . . . . . . . . . . . . . . . . . 19

Cross-References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Introduction

Congenital lung malformations are uncommonbut extraordinarily diverse in their presentation.Given that the potential consequences may be life-threatening, an understanding of the diagnosis andtreatment of these anomalies is important to allphysicians and surgeons who care for infants andchildren. The presentation of these lesions occursin a spectrum, from antenatal diagnosis to presen-tation in adulthood. These lesions may also varyfrom asymptomatic to immediately life-threatening in nature. To begin to understand thepathophysiology of these malformations, onemust first start with a basic understanding oflung development, as well as respiratory anatomyand physiology, which are presented below. Themost common congenital malformations such ascongenital pulmonary airway malformations, pul-monary sequestrations, lobar emphysema, andbronchogenic cysts, as well as a number of lesscommon anomalies will be discussed.

Embryology

Development of the respiratory system begins dur-ing the third week of gestation as a diverticulum ofthe ventral foregut. This diverticulum is primarilyendodermal in origin but derives cartilaginous andmuscular elements from the surrounding splanch-nic mesoderm. During the fourth week, theesophagotracheal septum forms through fusion ofthe esophagotracheal ridges, completely separatingthe developing respiratory system and foregutexcept at the larynx. As development progresses,

the endodermal diverticulum will become the epi-thelial lining of the larynx, trachea, bronchi, andalveoli. By the end of week 6, the trachea hasundergone division into the right and left main-stem bronchi. Proliferation of mesenchyme in themediastinum provides the mesoderm which even-tually develops into the cartilaginous, smooth mus-cle, and connective tissue of the lung.

The pulmonary vasculature develops in paral-lel to the surrounding lung tissue. This tissue isderived from the mesoderm around the primitivelung buds and begins to develop at 7–8 weeks ofgestation. Pulmonary blood flow slowly matures,and by the seventh gestational month, gasexchange is possible.

The endodermal diverticulum continues to pro-gressively branch; segmental and lobar branchingis complete by the ninth week of gestation andcoincides with closure of the pleural peritonealcanal and the formation of the diaphragm. As thelung continues to expand and grow, the lung budscome to nearly completely fill these canals, leav-ing only a small residual space which becomes thepleural cavity. By the sixth month of gestation,approximately 17 generations of subdivisionshave been formed, giving rise to the respiratorybronchioles. At this point in gestation, many con-genital pulmonary malformations are evident. Ifone considers the rapid expansion of pulmonaryparenchyma during this period of development, itis easily understood how a congenital pulmonarylesion can have a significant impact on fetal lungdevelopment and postnatal respiratory physiol-ogy. Development and maturation of the alveolioccur during the third trimester. The number andsize of the alveoli continue to increase during thistime, but it is important to recognize that thisprocess is not complete until well into childhood.An additional six divisions of the airways occurduring early postnatal life, and lung developmentcontinues until approximately 8 years of age(Thurlbeck 1975). When considering congenitallung lesions and their treatment, this is critical:because of continued lung development well intochildhood, pulmonary resection in infants andchildren is extraordinarily well tolerated, withlittle impact on long-term respiratory physiology(Gray and Skandalakis 1972).

2 K.T. Oldham and K.M. Dominguez

Anatomy

A brief discussion of relevant anatomy is presented.For a more detailed review, several excellent refer-ences are available (Agur and Dalley 2013; Netter2011). The location of the carina is dependent onage, but in a term infant is located at the fourth orfifth vertebral body. The main stem bronchus of theright lung is larger in diameter, shorter in length,and more vertical in direction than the left mainstem bronchus; these anatomic differences accountfor the preference of aspirated material and deependotracheal tubes to enter the right main stem. Inthe infant and child, the hilum of either lung isbeneath the fifth intercostal space on the lateralchest wall. A thoracotomy through this space pro-vides optimal exposure for pulmonary resection.The relationship of the hilum to other mediastinalstructures is demonstrated in Fig. 1. The matureright lung is composed of three lobes, in contrastto two lobes on the left; the lungs are further sub-divided into anatomic segments.

The pulmonary artery circulation is dedicatedto gas exchange; the vascular supply of the tra-chea, bronchi, and lung parenchyma is systemic innature. The trachea is supplied by branches of theinferior thyroid arteries, which anastomose withthe bronchial blood supply, derived from the aortaon the left and the third intercostal artery on theright. Venous drainage is by the azygous andhemiazygous systems. This arterial supply andvenous drainage generally follow the segmentalarchitecture of the lung and bronchial tree (Agurand Dalley 2013; Netter 2011; Oldham 2005).

Congenital Pulmonary AirwayMalformations/Congenital CysticAdenomatoid Malformations

Pathology

In 1949 Ch’in and Tang described a mass lesion ofgland-like (adenomatoid) alveoli, coining the term“congenital adenomatoid malformation.” Over thenext 30 years, a variety of lesions, both cystic andnot, were grouped together under the heading ofcongenital cystic adenomatoid malformation

(CCAM), with subdivisions based on the size ofthe cysts. The term congenital pulmonary airwaymalformations (CPAMs) was developed byStocker, attempting to better clarify and subdividethis disease process based on the presumed originof the abnormal lung tissue (Fig. 2). This classifi-cation system carries both descriptive and prognos-tic significance, given that certain subtypes (1 and4) carry increased risk of malignancy(MacSweeney et al. 2003; Stocker 2009).

Today, these terms are used somewhat inter-changeably, though inconsistency continues toexist regarding the correct nomenclature. For thepurposes of this chapter, this group of lesions willbe referred to as CPAM and is generally defined asbenign hamartomatous or dysplastic tumors char-acterized by overgrowth of terminal bronchioles ina glandular or adenomatoid pattern. These lesionsare relatively uncommon, with an estimated inci-dence of 1 in 25,000 to 1 in 35,000 (Duncombeet al. 2002), but constitute up to 50–70% ofbronchopulmonary foregut malformations in somereports (Adzick et al. 1998; Wolf et al. 1980).CPAMs are thought to result from marked over-growth of terminal bronchioles at the expense ofalveolar development. Grossly, these lesions arelarge, firm multicystic masses and are characterizedby interconnected disorganized cysts. Histology ofCPAM lesions demonstrates ciliated cuboidal orcolumnar cells lining the cysts and a notable lackof normal architecture. A component of bronchialatresia is identifiable in most CPAM lesions andmay contribute to their pathogenesis. These lesionstypically communicate with the normal bronchialtree and have a normal vascular supply (Rashadet al. 1988). A single lobe is generally affected;there is a slight predilection for the lower lobes,with right and left sides affected equally.

Diagnosis

Radiographic

Currently, the majority of cystic lung lesions areidentified on prenatal ultrasound (US), whichdemonstrates an echogenic pulmonary mass withdisplacement of adjacent structures. The location

Congenital Malformations of the Lung 3

of the stomach bubble is helpful in distinguishingbetween CPAM and congenital diaphragmatichernia (CDH), though some difficult cases mayrequire prenatal magnetic resonance imaging(MRI) for definitive diagnosis (Hubbard et al.1999). Adzick and colleagues used antenatal USand defined CPAM as either macrocystic (greaterthan 5-mm diameter cysts) or microcystic (solid orless than 5-mm diameter cysts); however, overallsize and degree of compression of adjacent struc-tures ha a greater impact on the natural history ofCPAM than does gross appearance. Physiologicconsequences may be severe, with significantcompression of the mediastinum, resulting inhydrops fetalis and fetal demise. Conversely,serial US exams may show shrinkage or even

spontaneous resolution in up to 40% of prenatallyidentified CPAMs (Adzick et al. 1998; vanLeeuwen et al. 1999).

The differential diagnosis of cystic and masslesions noted on prenatal US includes CPAM,CDH, pulmonary sequestration, and broncho-genic cyst. Differentiation between these entitiescan often be made by the associated findings:CPAMs are associated with polyhydramnios(thought to be secondary to esophageal compres-sion and impairment of fetal amniotic fluidswallowing), pleural effusions, and fetal hydrops(resulting from mediastinal shift and diminishingcardiac output from caval obstruction) (Adzicket al. 1998). Any of these findings during preg-nancy are associated with a poor outcome.

Bronchial arteriesoriginating fromdescending thoracicaorta

Pulmonaryartery

Aorta

Vagus nerve

Right recurrentlaryngeal nerve

Ligamentumarteriosum

Trachea

Esophagus

Left recurrentlaryngeal nerve

Vagus nerve

Fig. 1 Key anatomic relationships of the structure of the pulmonary hilum (Modified from Oldham 2005, p. 952)

4 K.T. Oldham and K.M. Dominguez

Conversely, mortality approaches zero for a fetuswith a CPAM and no associated hydrops.

Crombleholme et al. developed and proposedUS determination of the CPAM volume ratio(CVR) to aid in predicting risk of developinghydrops fetalis. CVR = (CPAM Length �Height � Width � 0.52)/head circumference. ACVR of �1.6 (lesions with a dominant cystexcluded) predicts a low risk (<3%) for the devel-opment of hydrops, whereas a CVR>1.6 predictsfetal hydrops in 75% of patients. In their series,postnatal intubation was required in fewer than7% of patients with a CVR�1.6, and the survivalrate was 94%. In contrast, when CVR was >1.6,intubation was required in 88% of patients andsurvival was 53%. They also observed that thegreatest increase in CVR occurred between 20-and 26-week gestation, and thereafter the CVRplateaus or diminishes with continued fetalgrowth (Crombleholme et al. 2002). Further stud-ies have confirmed these findings, citing a strongcorrelation between the CVR, the development ofhydrops, and the need for fetal intervention (Casset al. 2011). For these reasons, surveillance US issuggested in fetuses with a known CPAMs whichare less than the estimated gestational age of28 weeks. These are performed twice weekly ifthe CVR is greater than 1.6 and once weekly if theCVR is 1.6 or less, to evaluate for an increasingCVR or the development of hydrops.

Postnatal diagnosis can often be made by plainchest radiographs; a nasogastric tube is helpful indistinguishing between CPAM and CDH, as anintrathoracic stomach is common with left CDH.In a stable patient, CT and MRI are helpful todefine anatomy and identify aberrant systemicblood supply that is more suggestive of a pulmo-nary sequestration (Fig. 3). A CT scan is moreaccurate than plain chest radiography inconfirming complete resolution of an prenatallydiagnosed congenital pulmonary lesion that is notapparent on postnatal plain chest radiography, asresidual parenchymal abnormalities may still bepresent (van Leeuwen et al. 1999).

Clinical Features

The natural history of a CPAM diagnosed prena-tally is highly unpredictable and variable.Approximately one third of patients will be symp-tomatic in the neonatal period (Wang et al. 1999).These patients may demonstrate tachypnea, dys-pnea, cyanosis, or even impending respiratoryfailure as a consequence of mass effect. The pre-sentation in these patients can be dramatic andmay demand intervention in the neonatal period.However, the majority of patients are asymptom-atic at birth and present instead with recurringpersistent respiratory infections during the first

0

1

2

34

Fig. 2 CPAMclassification based onpresumed site ofdevelopment of themalformation.0 = tracheobrohial,1 = bronchial/bronchiolar,2 = bronchiolar,3 = bronchiolar/alveolar,4 = distal acinar (FromStocker 2009)

Congenital Malformations of the Lung 5

few years of life. This may result in the formationof pulmonary abscesses or development of reac-tive airway disease. In a small cohort of patientswith unresected CPAM, Aziz et al. found a 10%incidence of infectious complications by the ageof 3 years (Aziz et al. 2004). The long-term inci-dence of infections is likely higher. Ultimately,these chronic pulmonary problems may also leadto failure to thrive. In those patients who requirerespiratory support or fail to thrive as a result ofincreased work of breathing, neonatal surgicalresection is indicated.

Less commonly, a CPAM is diagnosed in achild or during adulthood in association with apulmonary malignancy. More than 40 cases ofCPAM associated with a bronchoalveolar carci-noma (BAC), sarcoma, pleuropulmonaryblastoma (PPB), mesenchymoma, or mucinousadenocarcinoma are reported in the literature.

Management

Fetal Therapy

Fetal treatment of surgical disease remains one ofthe more controversial areas in pediatric surgerydue to the high risk of complication and mortalityfor both fetus and mother. For CPAMs, it is clear

from the literature that treatment should be expec-tant management with term delivery and postnatalevaluation, except in those cases where the fetusdevelops hydrops or physiologic distress. What, ifany, treatment should be offered to fetuses whodemonstrate fetal hydrops or distress is less clear.As stated above, previously published experiencedemonstrated universal fetal demise in fetuseswith cystic pulmonary lesions and hydrops.More recently, published reports indicate that thedevelopment of hydrops in a fetus with a CPAMmay not be uniformly fatal, and the risk of fetalloss may be further decreased by systemic mater-nal steroid administration during the second tri-mester. In fetuses with US evidence of fetalhydrops, intervention should be considered.Maternal steroid administration to any affectedfetus less than the estimated gestational age of34 weeks is reasonable (Curran et al. 2010).When hydrops develops during the third trimester,one option is an ex utero intra partum therapy(EXIT) procedure with thoracotomy and lobec-tomy using placental bypass, permitting saferesection and avoiding respiratory collapse. Casset al. recently reported a 100% survival rate forinfants undergoing an EXIT procedure; fetuseswere identified as high risk either because offetal hydrops or CVR >1.6, and EXIT wasperformed in those who demonstrated persistent

Fig. 3 Term female infant with prenatally diagnosedCPAM. CXR (a) shortly after birth demonstrates leftlower lobe CPAM. Preoperative CT angiogram

(b) demonstrates the CPAM (white arrow) but also iden-tifies an extralobar sequestration (black arrow), adjacent tothe left lower lobe

6 K.T. Oldham and K.M. Dominguez

mediastinal compression near birth (Cass et al.2013). Conversely, of the patients who did notundergo EXIT, all required emergent surgery asneonates, and two died. If the fetus is in the secondtrimester, several options exist for fetal interven-tion. Intrauterine thoracoamniotic shunting maybe performed with US guidance for a CPAMwith a large cyst; this intervention has the bestoutcome with the lowest fetal and maternal risk.Of 23 such patients treated with this approach inone series, the volume reduction of the CPAMwas 70%, and survival through the neonatalperiod was 74% (Wilson et al. 2006). Openmaternal-fetal surgery with pulmonary resectionof a large CPAM yields a >50% probability ofsurvival to discharge from the NICU, but giventhe technical complexity, this should only beperformed in a center with experience in openmaternal-fetal surgery. Due to the complexity ofthis decision making process and the expertisenecessary to make any needed intervention, refer-ral to a tertiary care center is appropriate at thetime of diagnosis of any CPAM.

Postnatal Therapy

Any symptomatic newborn necessitates promptsurgical intervention. Some infants who did notshow evidence of compromise in utero will dete-riorate as the abnormal lung tissue becomes pro-gressively distended with the postnatalphenomenon of air trapping related to breathingor positive pressure ventilation. Many infantsremain asymptomatic in the newborn period, anddelaying resection until later in infancy is reason-able. This approach allows somatic growth andmay facilitate the ease of pulmonary resection.Delaying resection until later in infancy does notappear to pose an increased risk of complications(Colon et al. 2012) and allows the opportunity forspontaneous resolution to occur. Complete spon-taneous resolution of a CPAM identified on post-natal imaging is rare but may occur in more than4% of patients (Butterworth and Blair 2005).Because congenital pulmonary lesions maybecome undetectable by ultrasound and plainradiograph, axial imaging using chest CT or

MRI is necessary to ensure complete resolution.Asymptomatic but persistent CPAM generallyshould be resected during infancy to prevent com-plications of recurrent infections or malignantdegeneration (Kapralik et al. 2016; Singh andDavenport 2015).

Resection typically includes formal lobectomyand is very well tolerated in infants and children.For small CPAM, nonanatomical resection is areasonable option and does not appear to haveincreased risk of perioperative morbidity (John-son et al. 2011). Nonanatomic resection may alsobe useful when multilobar disease is present.Occasionally, pneumonectomy is required. Forchildren who present with acute pulmonary infec-tion, it is appropriate to treat first with antibioticsand then plan for elective lobectomy. Tradition-ally, resection was performed through open thora-cotomy, but recent reports have demonstratedexcellent outcomes for minimally invasive pul-monary resection (Mattioli et al. 2016). This willbe further discussed later in the chapter.

While the majority of surgeons recommendresection of these lesions even in asymptomaticpatients due to the risk of infection and malig-nancy, there is controversy regarding thisapproach. Proponents of expectant managementpoint out that little is known about the naturalhistory of these lesions, particularly in the age ofprenatal US diagnosis, when more lesions arebeing diagnosed than ever before. Operative ther-apy inherently carries a risk of morbidity andmortality, while little is known about the truerisk with expectant management. Some reviewsof the literature have suggested that the incidenceof malignancy in those with CPAMs is no higherthan that in the population without CPAMs(Hammond et al. 2010). While pleuropulmonaryblastoma (PPB) may occur at a young age and bedifficult to differentiate from CPAM without apathologic specimen, certain patients who are atincreased risk can be identified and offered elec-tive resection. Patient characteristics such asmultifocal/bilateral lesions, associated pneumo-thorax or renal cystic nephroma, and a familyhistory of various tumors (including PPBs, renalnephromas, bladder rhabdomyosarcomas,gonadal germ cell tumors, papillary carcinomas,

Congenital Malformations of the Lung 7

and nodular hyperplasia of the thyroid gland) areall associated with PPB (Hammond et al. 2010).Bronchoalveolar carcinoma (BAC) may also beseen in association with CPAM but is typicallyseen in older children and adults, with low overallincidence. BAC is only associated with the type1 CPAM subtype (MacSweeney et al. 2003);however, the lesions must be resected and undergohistopathologic examination in order the diagno-sis. Other types of malignancy are extremely rare.Arguments in favor of early resection include alower risk of perioperative complications, as dem-onstrated in a meta-analysis (Stanton et al. 2009),and better long-term long function in youngerpatients who were resected before symptomsarose (Komori et al. 2009). The exact risks orpotential advantages of expectant management inthe setting of CPAM cannot be defined without aprospective trial. That is unlikely to occur giventhe concerns by many in the medical communityregarding the implications of recurrent infectiouscomplications and malignancy.

Pulmonary Sequestrations

Pathology

Pulmonary sequestrations account for roughly onethird of cystic bronchopulmonary foregutmalformations (Ryckman and Rosenkrantz 1985;Schwartz and Ramachandran 1997). The majorityof these lesions are intrathoracic and are furtherclassified as intralobar or extralobar based onwhether the lesion is within the visceral pleura ofthe normal lung or invested by its own pleura(Table 1). In both types of pulmonary sequestra-tion, there is no bronchial communication with thenormal tracheobronchial tree. Also, the sequestra-tion receives its blood supply from an aberrantsystemic arterial vessel, typically the aorta. Pulmo-nary sequestrations may also occur in extrathoraciclocations. Histologically, pulmonary sequestrationsdemonstrate immature lung development, oftenresembling more peripheral lung parenchyma.

Intralobar sequestrations account for 50–70% ofpulmonary sequestrations, and most often involvethe posterior or basal segments of the left lower

lobe (Frazier et al. 1997). These intralobar lesionsare surrounded by normal lung parenchyma andshare the visceral pleura. The arterial supply istypically from the descending thoracic aorta butcan also be from intercostal, brachiocephalic, orabdominal aortic aberrant branches. Venous drain-age is usually via the pulmonary vein that isdraining the accompanying normal lung tissue.Though by definition these lesions lack normalcommunication with the tracheobronchial tree,there may be communication via abnormal air-spaces. These abnormal communications can leadto air trapping within the lesion, as well as providea route for colonization with infectious pathogens.

Extralobar sequestrations are completely sepa-rated from the normal lung and are invested inseparate visceral pleura. As such, they are alsocompletely separate from the functioning airways.These lesions are most commonly found adjacentto the left lower lobe but can occur anywhere inthe chest; extrathoracic locations have also beendescribed, including intradiaphragmatic and sub-diaphragmatic locations. As with intralobarsequestrations, the typical arterial supply is fromthe descending thoracic aorta, though approxi-mately 20% have anomalous blood supply froman infradiaphragmatic vessel. Venous blood drain-age is typically into systemic veins, such as theazygous, hemiazygous, or portal system, andoccasionally directly into the atrium. Theselesions are prone to hemorrhage or arteriovenousshunting; patients may present with high-outputcardiac failure. In addition, extralobar sequestra-tions are associated with CPAM and CDH(Conran and Stocker 1999), as well as manyother congenital anomalies (Oldham 2005;Ryckman and Rosenkrantz 1985). Figure 3 dem-onstrates an infant with a left lower lobe CPAMand extralobar sequestration.

The embryologic origin of pulmonary seques-trations remains unclear. Theories include abnormalbudding of the tracheobronchial tree or accessorybudding from the primitive foregut, either leadingto an orphaned lobe. The stimulus is unknown.Regardless of the embryologic origin, these lesionsare clearly congenital in nature, as evidenced bytheir presence in neonatal autopsies, evermore fre-quent prenatal US diagnosis, and frequent

8 K.T. Oldham and K.M. Dominguez

associationwith other congenital anomalies in up to40% of patients. Rarely, pulmonary sequestrationscommunicate outside the respiratory tract with theesophagus or stomach, as all these structures sharederivation from the embryonic foregut.

Diagnosis

Intralobar sequestrations typically are not diag-nosed until symptoms develop. Given that theselesions are surrounded by normal lung parenchyma,they are often difficult to distinguish on imagingstudies until pathologic events develop. Patientswith intralobar sequestrations most often presentwith pulmonary infections which occur secondaryto abnormal airspace connections and poor drainage(Fig. 5). These lesions can also cause compressiveatelectasis of adjacent normal lung parenchyma,leading to infection. Most commonly, diagnosis islater in childhood or adulthood, in a patient withrecurrent pneumonias, lung abscess, or hemoptysis.With the now commonplace use of antenatal US,these lesions are increasingly diagnosed prenatallyand may appear similar to a CPAM or CDH. Theymay be associated with pleural effusion, poly-hydramnios, or hydrops fetalis. Sixty percent ofthese lesions occur on the left side and most com-monly involve the left lower lobe.

Extralobar sequestrations are often diagnosedon antenatal ultrasound. These lesions appear as

an echogenic thoracic mass, 90% of which occuron the left in the posterior mediastinum. They canbe difficult to differentiate from a CPAM or CDHby US, though anomalous blood supply is oftenidentified on Doppler examination and may aid inidentifying these lesions. Like intralobar seques-trations, these lesions may cause symptoms sec-ondary to mass effect, particularly if large.Mediastinal shift, hydrops fetalis, or fetal demisecan occur. Congestive heart failure may resultfrom arteriovenous shunting within the lesion.These lesions are also more commonly noted pre-natally or early in infancy due to the association ofother anomalies and the evaluation required forthese other problems.

Postnatal plain chest radiography will occa-sionally be diagnostic for a sequestration. Morecommonly, plain films demonstrate a retrocardiacposterior mediastinal mass if extralobar (Fig. 4) ora nonaerated mass within the lung if intralobar.Neither finding is specific for a sequestration, andadditional imaging is required to make a definitivediagnosis. Ultrasound may be helpful, but axialimaging such as CT and MRI provides greateranatomic detail as well as identifying anomalousarterial supply. The differential diagnosis oftenincludes CPAM, CDH, and other posterior medi-astinal masses such as neuroblastoma. Despitemodern imaging advances, these lesions may bedifficult to differentiate and sometimes cannot bedifferentiated without surgical excision.

Table 1 Intralobar versus extralobar pulmonary sequestration

Intralobar Extralobar

Gross findings Invested in pleura of normal lung Separate pleura from normal lung

Location Lower lobes (90%) Left lower hemithorax(75%); may occur outsidethorax

Sex (M: F) 1:1 4:1

Associatedanomalies

Rare Frequent (60% of patients): CHD, other congenitallung malformations, CDH

Arterial supply Descending aorta (95%), celiac or splenic(20%)

Descending aorta (75%)

Venousdrainage

Pulmonary veins (95%) Systemic veins (75%)

Age ofpresentation

Usually over 1 year <6 month or prenatally

Presentation Typically recurrent infection; rarely: CHF,failure to thrive, PTX

Incidental finding, respiratory distress, CHF

CHD congenital heart disease, CDH congenital diaphragmatic hernia, CHF congestive heart failure, PTX pneumothorax

Congenital Malformations of the Lung 9

Management

The hallmark for treatment of pulmonary seques-trations is surgical excision of the abnormal lungtissue. Abnormally developed lung tissue is notbeneficial to the patient. Although some lesionsmay remain asymptomatic, the risks of hemor-rhage, infection, arteriovenous shunting, or latemalignancy are real and may result in significantmorbidity or mortality for the patient.

Prenatal management is identical to that forCPAM. In cases where fetal compromise is occur-ring due to the lesion, such as tension hydrothoraxor hydrops fetalis, fetal interventions such asthoracoamniotic shunting and drainage may behelpful but remain controversial. Although a fewobservational studies of small cohorts of patientswith unresected extralobar sequestrationsfollowed over a short period of time appear tohave a low risk of complications, in general, post-natal resection of a sequestration is indicated forthe reasons outlined above. As in the CPAM pop-ulation, resection is recommended before symp-toms develop, generally before the age of 1 year.Arterial embolization has also been reported but isnot widely practiced (Curros et al. 2000).

For extralobar sequestration, resection isaccomplished by either thoracotomy orthoracoscopy. As the lesion is separate from

normal lung, the procedure is relatively straight-forward. Intralobar sequestration may presentmore of a challenge; this lesion is generally treatedwith lobectomy either via thoracotomy orthoracoscopy. In some cases, particularly whereprenatal diagnosis has led to discovery in anasymptomatic patient, segmentectomy may be anoption. While the goal of resection is to removeonly abnormal lung tissue, in patients who havebecome symptomatic due to infection, the degreeof inflammation usually necessitates lobar resec-tion. Preoperative treatment with antibiotics isadvisable if infection is presents and may helpdecrease inflammation. Figure 5 demonstrates apatient with an extralobar sequestration and pneu-monia and the response to antibiotic treatment.

Technical aspects important in the surgicalresection of pulmonary sequestrations includeidentification and control of anomalous vascula-ture and preservation of the phrenic nerve. Preop-erative imaging can be helpful in identifying bloodsupply and preoperative planning. Some lesionshave arterial supply from an infradiaphragmaticorigin and course through the inferior pulmonaryligament; if this is unrecognized prior to division,or not properly controlled, the vessel may retractinto the abdomenwith significant blood loss. Addi-tionally, abnormal foregut communications mustbe recognized and appropriately controlledintraoperatively.

Fig. 4 Preoperative plain chest radiography (a) and chestCT (b) of a patient with an extrapulmonary sequestration.Chest CT demonstrates a well-circumscribed solid mass inthe left posterior mediastinum. The lesion failed to

demonstrate signs of resolution on serial chest CT andwas resected at 4 months of age (Modified from Puri2009, p. 301)

10 K.T. Oldham and K.M. Dominguez

Congenital Lobar Emphysema

Pathology

Congenital lobar emphysema (CLE), also knownas congenital lobar overinflation, is characterizedby air trapping within the affected lobe, whichusually otherwise anatomically normal. The airtrapping leads to overdistension of the affectedlobe and compresses the adjacent lung and medi-astinal structures, which may lead to hemody-namic or respiratory compromise. The lung

parenchyma is typically normally developed.Though an etiology is not identified in up to halfof reported cases (Lewis 1980), it is believed toresult from bronchial collapse secondary to defi-ciency or absence of the cartilaginous componentsof the bronchus, resulting in air trapping withinthe affected lobe (Haller et al. 1979). Other poten-tial etiologies, which typically are only seen out-side the newborn period, include endobronchialobstruction due to secretions, granulation tissue,foreign bodies, or tumors, all of which similarlylead to air trapping. For this reason,

Fig. 5 A 16-year-old male presented with fevers, cough,and hemoptysis. CXR (a) demonstrated a large left lowerlobe (LLL) cavitary pneumonia. Chest CT (b) at that timerevealed an infected pulmonary sequestration, with pneu-monia in the adjacent LLL. After antibiotic treatment (c),

the normal lung had improved significantly, though con-solidation remained in the sequestration. A CT angiogram(4) was performed to identify vascular supply, and a largefeeding vessel off the thoracic aorta was identified

Congenital Malformations of the Lung 11

bronchoscopic evaluation is recommended toavoid unnecessary lung resection. In addition,extrinsic compression can also result in air trap-ping and occur as a result of mediastinal lymph-adenopathy, anomalous or enlarged blood vessels,congenital heart disease, and bronchogenic orenteric cysts or tumors (Coran and Drongowski1994).

Rarely, an apparent CLE is found histologi-cally to have a proliferation of normal alveoliwithin the affected lobe without bronchialobstruction. This is termed polyalveolar morphol-ogy. Similarly to CLE, the increase in alveolileads to expiratory air trapping and over disten-sion with respiratory compromise. The diagnosisand treatment of polyalveolar morphology is thesame as that for CLE.

The incidence of CLE is estimated at 1 in20,000–30,000 live births (Thakral et al. 2001)and is most commonly seen in the Caucasianpopulation with a 2:1 or 3:1 male predominance.The left upper lobe is most commonly affected(40–50%), followed by the right middle lobe(30–40%) (DeLorimer 1986; Murray 1967).Lobar emphysema may be associated with con-genital heart disease or abnormalities of the greatvessels in 15% of infants (Buntain et al. 1974); forthis reason, screening echocardiography isrecommended in all infants with CLE.

Diagnosis

Presentation and Diagnosis

In contrast to other congenital pulmonarymalformations, the diagnosis of CLE is rarelymade by antenatal US or MRI as the process ofair trapping occurs postnatally. This diagnosis canbe difficult to differentiate from a microcysticCPAM as both may appear as an echogenic massprenatally. Despite this, there have been reports ofprenatal diagnosis of this lesion.

Contrary to the name, CLE does not occurimmediately at birth, as breathing is a postnatalphenomenon. Symptoms develop as lobar disten-sion progresses over time. Severity of disease is

generally related to the age of presentation, withthe most threatening presentations occurring innewborns. Most commonly, the diagnosis ofCLE is made by plain chest radiography in anewborn with respiratory distress. Shortly afterbirth, a lobe affected by CLE may appear consol-idated on chest radiography as a result of inade-quate clearance of amniotic fluid from the affectedlobe. As distension of the affected lobe pro-gresses, radiographic findings include hyperinfla-tion of the affected lobe, mediastinaldisplacement, atelectasis of the adjacent lung,and flattening of the hemidiaphragm (Fig. 6). Ten-sion pneumothorax may appear similar on chestradiograph but is differentiated by complete col-lapse of the entire ipsilateral lung into the hilumwith absent peripheral lung markings. In CLEcompressed normal lung is seen on the affectedside. Further imaging beyond plain chest radiog-raphy is rarely necessary in newborns and infantsand in some cases contraindicated due to the needfor emergent operative intervention. In older chil-dren, CT, MRA, and bronchoscopy are helpful toevaluate for reversible causes of lobar emphysemaand may prevent unnecessary lung resection.

Clinical Features

Congenital lobar emphysema is most commonlyfound in term infants; however, acquired emphy-sema can occur in premature infants as a result ofbarotrauma, oxygen toxicity, and lung immaturityand may have very similar clinical consequences.Following birth, spontaneous respiration leads toprogressive over distension of the affected lobeand compression of normal lung. Initial symp-toms include tachypnea and wheezing. Cyanosisoccurs when oxygenation is sufficiently impaired.As the infant becomes more distressed, air trap-ping is worsened by excessive respiratory effort.This process can be exacerbated by the need forpositive pressure ventilation and may in fact leadto rapid decompensation. Half of affected infantswill demonstrate develop respiratory distress inthe first few days of life; the remainder developssymptoms within the first few months or years of

12 K.T. Oldham and K.M. Dominguez

life. Rapidly progressive respiratory failure occursin up to 10–15% of newborns. In those patientswith rapidly progressive symptoms, emergencythoracotomy allows for decompression of the tho-rax, followed by definitive lobectomy.

Physical findings of congenital lobar emphy-sema include diminished breath sounds and focalhyperresonance on the affected lobe, an asymmet-ric thorax, and shift in the apical impulse to thecontralateral side. As these findings are not diag-nostic or specific, the diagnosis is best establishedwith plain chest radiography. Additional imagingis reserved for older children or those cases inwhich the diagnosis is unclear.

Management

Lobectomy is indicated in any symptomaticpatient with CLE. This may be safely achievedby either traditional open thoracotomy orthoracoscopy. In a newborn with severe respira-tory distress as a result of CLE, emergent thora-cotomy with delivery of the affected lobe can belifesaving. Although generally unnecessary ininfants, children should undergo bronchoscopypreceding thoracotomy to evaluate for reversibleendobronchial lesions not requiring pulmonaryresection. Causes of extrinsic compression should

Fig. 6 Preoperative plain chest radiography (a) and chestCT (b) of congenital lobar emphysema of the left upperlobe. Note the hyperinflation of the left upper lobe,resulting in mediastinal shift and compressive atelectasis

of the normal lung parenchyma. Postoperative plain chestradiography (c) demonstrates resolution of the mediastinalshift and re-expansion of the normal lung parenchyma(Modified from Puri 2009, p. 302)

Congenital Malformations of the Lung 13

also be sought but are generally associated with afocal cartilaginous defect such that relief of theextrinsic compression will not relieve the bron-chial obstruction. Bronchoplasty is theoreticallyattractive; however, the size of the bronchus in aninfant or child makes bronchial reconstructiontechnically unsuccessful, while lobectomy in theinfant population is very well tolerated.

In premature infants who develop acquiredemphysema, the treatment is generally medicaland supportive. These infants often have a multi-tude of other problems and, in contrast to CLE,have disease involving multiple areas of the lung.Strategies used for treatment include selectiveventilation of nonemphysematous areas or theuse of alternative ventilator modes such as high-frequency oscillatory ventilation or jet ventilation.Lobectomy may be beneficial in select patientswho have disease isolated to one lobe, but carriessignificantly more morbidity than in patients withCLE, as the premature infants with acquiredemphysema do not have remaining normal lungparenchyma, rather chronic lung disease. In oneseries, infants requiring lobectomy demonstratedprompt physiologic improvement following sur-gery, but one third of the patients died within thefollowing 3 years due to respiratory insufficiency(Azizkhan et al. 1992).

Bronchogenic Cysts and CongenitalLung Cysts

Pathology

Bronchogenic cysts are developmental cysts aris-ing from the trachea or bronchus and are includedin the spectrum of bronchopulmonary foregutcystic malformations, accounting for up to onethird this category of malformations in somereports (Evrard et al. 1999; Wesley et al. 1986).These cysts are typically thick walled, unilocularcysts filled with mucus. The cyst wall is composedof the structural elements of the airway: smoothmuscle, cartilage, elastic tissue, and mucousglands and respiratory epithelium. Typical loca-tions include the cervical or thoracic trachea, hilarbronchi, or more distal intraparenchymal bronchi.

Ectopic locations have also been reported andinclude paravertebral, paraesophageal, pericar-dial, subcarinal, and subcutaneous locations.Bronchogenic cysts arise from the airway andtypically remain intimately attached; however,the communication with the airway is typicallylost during development. Bronchogenic cysts arebelieved to occur as a result of abnormal buddingof the tracheobronchial tree.

Parenchymal lung cysts are similar to broncho-genic cysts in terms of clinical significance andtreatment; however, in contrast, parenchymal lungcysts arise from the distal airways, alveoli, or maybe pleural in origin. The histology is variable butresembles the structure of origin. Differentiationof parenchymal cysts from bronchogenic cysttends to be difficult short of resection. The fea-tures of presentation and principals of manage-ment are similar to those for bronchogenic cysts,except when the cyst is lymphatic in origin. Whenthe cyst is lymphatic in origin, widespread pulmo-nary lymphangiectasis may be present and is asso-ciated with diffuse bilateral cystic lunginvolvement and a poor prognosis (Oldham2005). Although collectively parenchymal lungcysts are rare, infection of these cysts is notuncommon as a result of communication withthe airways.

Presentation and Diagnosis

Some patients with bronchogenic cysts or paren-chymal lung cysts are asymptomatic. Presentationranges from an incidental finding on imaging tolife-threatening respiratory distress, though thelatter is rare. As with other congenital cysticlung lesions, physiologic injury occurs due tocompression of adjacent structures, such as theproximal airways or esophagus, or from impaireddrainage of secretions in the lesion or adjacenttissue leading to infection. If a patent connectionto the tracheobronchial tree is present, infectionmay develop, and presentation with fever, chills,productive cough, or hemoptysis is typical. Mostcommonly, infants present respiratory symptomsrelated to obstruction/compression of adjacentstructure or, less commonly, failure to thrive.

14 K.T. Oldham and K.M. Dominguez

Older children usually present with infectiouscomplications. Rarely, cysts may enlarge to thepoint of causing significant mass effect with medi-astinal displacement, airway compression, andcardiorespiratory compromise. Secondary malig-nancy of these lesions has also been reported.

Plain chest radiography typically demonstratesa smooth, roughly spherical mass in either a para-tracheal or hilar mass without calcification(Fig. 7). Displacement of adjacent airway is rela-tively common, and evidence of distal air trappingmay be noted even in asymptomatic patients. Ifthe cyst is infected or communicates with theairway, an air fluid level may be present. CT andMRI are useful adjuncts for defining pertinentanatomy and will demonstrate a cystic lesionwithout calcification (excluding a neuroblas-toma). Contrast-enhanced studies will demon-strate a nonenhancing mass lesion, which helpsto differentiate bronchogenic cysts from an aber-rant pulmonary artery (pulmonary sling). Addi-tionally, anatomic relationships to adjacentmediastinal structures can be defined (particularlythe spine) and allow differentiation between bron-chogenic cysts and neurenteric cysts. Anesophagram can be helpful in selected cases toevaluate for foregut communication. Foregutduplication cysts, neuroblastoma, neurentericcysts, pericardial cysts, and lymphoma areincluded in the differential diagnosis dependingon cyst location.

Management

Resection is indicated to alleviate symptoms, pre-vent infection, provide pathologic identification,and prevent future malignancy. Rarely, acutedecompensation from a large bronchogenic cystor parenchymal cyst may require emergent treat-ment with needle decompression or tubethoracostomy placement as a temporizing mea-sure. Generally, simple local resection can beaccomplished with preservation of adjacent nor-mal lung parenchyma. In cases where infection ofthe cyst or pneumonia is present at the time ofdiagnosis, treatment with antibiotics preopera-tively is appropriate. Resolution of active

infection prior to resection is helpful to minimizeunnecessary pulmonary resection. Formal pulmo-nary resection may be required due to the ana-tomic location of the cyst (particularly forparenchymal lung cysts) or secondary to inflam-mation from previous infections. In some cases, itis not possible to remove the cyst without sacrific-ing vital structures; in these cases, partialcystectomy with fulguration of any remainingcyst wall is indicated. Long term follow-up isnecessary as recurrences have been reported forpartially resected lesions.

As with the other previously described con-genital pulmonary malformations, resection canoften be accomplished with a minimally inva-sive approach and may be associated withshorter duration of thoracostomy drainage andhospital stay (Tölg et al. 2005). If a minimallyinvasive approach is planned, it is important toestablish anatomic relationships preoperatively,as bronchogenic cysts are often invested in themediastinal pleura and require pleural incisionand mediastinal exploration for excision. Ifan open approach is planned, lateral thoracot-omy is generally employed, although mediansternotomy may be useful for more centrallesions.

Pulmonary Hypoplasia, Aplasia,and Agenesis

Pulmonary hypoplasia is the abnormal develop-ment of an entire lung or both lungs, which resultsin a diminutive organ with dysfunctional gasexchange. Most commonly, this occurs as a resultof extrinsic compression during development,though may also occur primarily. The most com-monly responsible lesions are CDH and CPAM.Pulmonary aplasia is the result of developmentalarrest during organogenesis and results in a some-times marked reduction in the number of alveoli.The consequences of either derangement may besevere and include pulmonary hypertension, per-sistent fetal circulation, and respiratory failure.Significant clinical support, such as high-frequency oscillatory ventilation, inhaled nitricoxide or extracorporeal membrane oxygenation,

Congenital Malformations of the Lung 15

is frequently required, and mortality may resultdespite these interventions.

Pulmonary agenesis is the complete absence ofone or both lungs. The cause of this is unknownbut appears to result from a failure of organogen-esis when the trachea divides into two lung buds,during the fourth week of gestation. Bilateralinvolvement is very rare and is not compatiblewith survival. Unilateral involvement is rare, isseen with roughly equal incidence on right and leftsides, and is frequently associated with other con-genital abnormalities. There may be significantmanagement issues in the neonatal period, notonly due to respiratory insufficiency but also dueto the associated anomalies (Booth and Berry1967; Hoffman et al. 1989; Osborne et al. 1989).

This disorder is sometimes diagnosed in olderchildren who present with nonspecific respiratorysymptoms, failure to thrive, exercise intolerance,chest asymmetry, or scoliosis. For unclear rea-sons, these children also often present with pneu-monia or bronchitis, though functionalabnormalities of the remaining bronchus havebeen postulated. On physical exam, a shift in thelocation of heart tones and absent ipsilateralbreath sounds are notable. Plain chest radiographydemonstrates hyperinflation of the contralaterallung, displacement of the mediastinum, and afluid filled cavity on the involved side. The diag-nosis can be confirmed with endoscopy, echocar-diography, axial imaging, or angiography, whereabsence of the ipsilateral main stem bronchus or

Fig. 7 Preoperative plain chest radiography (a) and chestCT scan (b, c) of a 9-month-old patient presenting withcough. Plain radiography demonstrates a smooth, round,mediastinal mass causing significant tracheal deviation.Chest CT demonstrates a large, well-circumscribed,

middle mediastinal lesion displacing the trachea and greatvessels. The mass was resected through a mediansternotomy; pathology was consistent with abronchogenic cyst

16 K.T. Oldham and K.M. Dominguez

pulmonary artery is definitive. Figure 8 demon-strates left lung agenesis in a patient with multiplecongenital anomalies.

Treatment of unilateral pulmonary agenesis isnonsurgical and supportive. Aggressive antibiotictherapy is indicated in the setting of infection. Themajor surgical issues are related to the manage-ment of associated anomalies and avoidance ofputting the single remaining lung in jeopardy dur-ing any necessary operative interventions. Histor-ically, these patients have a high mortality rate,with about one-half failing to survive beyond thefirst 5 years of life (DeLorimer 1986). Deathsoften occur in the perinatal period, secondary toassociated anomalies or due to recurrent respira-tory infections. More recently, prognosis appearsto be improving.

Lung Surgery in Newborns

A brief discussion of thoracic surgical techniquesis appropriate. More detailed, comprehensiveatlases are available (Ferguson 1997; Sugarbakeret al. 1997). Lung surgery in neonates is similar tothat in adults, with the notable exception beingsize of the involved structures. Technical preci-sion is required in any thoracic procedure, butsmall infants have a notably smaller allowablemargin of error. Technical problems may resultin serious, irreversible consequences. Despitethis, lung resection in infants is very well toleratedand has an acceptable rate of complications.

Resection may be accomplished by traditionalthoracotomy or through minimally invasive tech-niques. Minimally invasive techniques(thoracoscopic resection) have demonstratedshorter duration of tube thoracostomy as well asshorter hospital stay without any difference inrates of complications when compared to openthoracotomy (Tölg et al. 2005). In addition, thisapproach minimizes the potential for future prob-lems with scoliosis related to division of chestwall musculature, which for traditional thoracot-omy (which historically also included rib resec-tion in many cases) has been estimated to occur inup to 50% of patients (Westfelt and Nordwall1991). Modern muscle sparing thoracotomy

(described below) is currently practiced when anopen approach is utilized in an attempt to mini-mize the likelihood of scoliosis. Pain is also pur-portedly less with thoracoscopic techniques,though this has been difficult to elucidate in thecurrent literature due to differences in evaluationand management.

For lesions approached either through tradi-tional thoracotomy or thoracoscopic approaches,the patient is generally placed in the lateraldecubitus position with the arm extended andplaced over the head. Positioning devices areused to optimize stabilization, expose the opera-tive field, and avoid prolonged pressure onnerves (particularly the brachial plexus, axillaryand peroneal nerves are at risk). Heat loss isalways a concern in pediatric surgery and canbe minimized with insulating coverings on non-operative areas as well as convective and radiantwarmers.

For open thoracotomy, optimal exposure isgained through a transverse or oblique incisionthrough the fourth or fifth intercostal space. Thisis performed below and lateral to the nipple toavoid damaging breast tissue. Care should alsobe taken to place the incision below the tip of thescapula to optimize exposure. The underlyingsubcutaneous tissues are divided along the lineof the incision, exposing the serratus anteriorand latissimus dorsi muscles. It is desirable toperform a muscle sparing technique in order tolimit postoperative morbidity from scoliosis. Thisis accomplished by mobilizing, but not dividingthe musculature, so they may be retracted out ofthe operative field. Following this, the scapula canbe retracted and the chest wall exposed, allowingpalpation of the ribs and determination of thecorrect interspace to enter the chest. The secondrib is usually the highest palpable rib in infantsand the fourth or fifth interspace desirable forentering the chest. The incision can then be con-tinued through the interspace, taking care to do sojust superior to the lower rib and avoid injury tothe neurovascular bundle which runs along theinferior surface of each rib. The pleura is thencarefully entered, to avoid injury to the underlyinglung, and a rib spreader placed to facilitateretraction.

Congenital Malformations of the Lung 17

General principles of lobar resection includehilar dissection, vascular control, and bronchialstump closure. In older children and adults, bron-chial stump closure is most easily accomplishedwith commercially available stapling devices. Innewborns and small children, the size of availableinstruments and resulting lack of precision makesthis approach undesirable; bronchial closure inthis population is best accomplished with a carefulhand sewn closure.

For some types of peripheral lesions, wedgeresection is easily accomplished and technicallystraight forward. Stapling devices work well onlung parenchyma even in small infants and aregenerally more reliable than hand sewn closures.Segmental lung resections are also sometimesappropriate for specific lesions (CPAM isolatedto a specific segments, and intralobar sequestra-tions are examples); however, the available liter-ature suggests that perioperative morbidity inregard to air leak and hemorrhage for segmentalresections may be greater than that for formallobectomy (Ryckman and Rosenkrantz 1985).

Following any type of resection, air leaks canbe identified by filling the chest with warm saline,while the anesthesiologist inflates the residuallobe. Suture repair is performed on any identifiedleaks. A tunneled chest tube is then placed in thepleural space for drainage and connected to a

closed suction system. The wound is closed inanatomical layers with absorbable suture.

Detailed thoracoscopic techniques are beyondthe scope of this chapter, but several useful prin-cipals bear mentioning. Due to the size of thepatient, double lumen endotracheal tubes are nota viable option for single lung ventilation. Thisdifficulty can at least in part be overcome by acombination of selective main stem intubation ofthe nonoperative side, the placement of a bron-chial blocker (balloon catheters work well forthis), or the use of low pressure insufflation ofthe chest to gently decompress the lung in theoperative field. Pressures of 5–7 mm Hg are gen-erally well tolerated without hemodynamic com-promise. The field of thoracoscopy in childrencontinues to evolve rapidly as new technologybecomes available. There is considerable appealto this approach for resection of congenitallesions, due to possibly equivalent outcomeswithout the morbidity of a thoracotomy incision.

Complications and Long-TermOutcomes

In the absence of diffuse lung disease or hypopla-sia, pulmonary resection is generally very welltolerated, even in newborns. Contemporary

Fig. 8 Female infant with prenatal diagnosis of CDH andcongenital heart disease. Postnatal plain chest radiography(a) with left CDH. Also notable are multiple rib anomalies,and no visible left lung. In addition, the patient had a limbanomaly. At the time of CDH repair, no lung was visible inthe hemithorax. A chest CT reconstruction (b) demonstrates

a blind ending left main stem bronchus. Echocardiographyconfirmed the absence of left pulmonary artery or veins.Plain chest radiography after repair of the CDH (c) demon-strates a hyperinflated right lung, tracheal shift toward theside with pulmonary agenesis, and a large effusion in theaffected hemithorax

18 K.T. Oldham and K.M. Dominguez

pediatric surgical series of pulmonary resectionfor congenital malformations report a mortalityrate of less than 2%. It is important to anticipatewhich infants will have increased morbidity andmortality. These can be identified when any of thefollowing are present: hydrops fetalis, significantmediastinal shift, pulmonary hypertension, orother associated anomalies. Short-term complica-tions following resection are infrequent andinclude prolonged air leak, pneumothorax, hem-orrhage, and infectious complications. Whetherusing an open or a minimally invasive approach,short-term complications do not appear to be anyhigher in infants compared to older pediatricpatients.

As discussed earlier, lung development occurswell into childhood; because of this, pediatricpulmonary resection is associated with excellentlong-term functional outcomes. In the absence ofother associated illness, most patients whoundergo pulmonary resection as an infant orchild will have normal somatic growth and normalpulmonary function. Laros demonstrated that byadulthood, children who had undergone pneumo-nectomy before age 5 had nearly fully compen-sated in terms of total lung capacity.Compensatory response was inversely related tothe age at the time of resection: children aged0–5 at time of resection had 96% expected totallung capacity at age 30, compared to 70% whenthe surgery occurred at 31–40 years of age (Larosand Westermann 1987). Similar adaptation oflung volume (total lung capacity and vital capac-ity) was observed in infants undergoing lobec-tomy for CLE (McBride et al. 1980). Of note,this study also found evenly distributed pulmo-nary blood flow between the operated and non-operated sides, suggesting compensatory growthof the pulmonary vascular bed.

It is likely that the compensation which occursfollowing childhood lung resection occursthrough a combination of further lung develop-ment and by compensation by the remaining lung.Regardless of the mechanism, excellent func-tional outcome has been associated with pediatricpulmonary resection. Little or no restriction inlifestyle is typically seen, even with major resec-tions in the absence of underlying lung disease. It

is however important to note that scoliosis andchest wall deformities are relatively frequent latecomplications after thoracic surgeries, a risk thatmay be mitigated with minimally invasivetechniques.

Conclusions and Future Directions

Congenital lung malformations are extraordi-narily diverse in their presentation, both in termsof symptomatology and age at diagnosis. Theselesions may be asymptomatic or immediately life-threatening in nature and may present anytimefrom the antenatal period to well into adulthood.Significant progress has been made in terms ofearlier diagnosis, so that the majority of patientsseen today are diagnosed antenatally and are oftenasymptomatic at the time of diagnosis. Minimallyinvasive surgical techniques continue to improveand are becoming more widely used. The role offetal intervention is still evolving but clearlyshould be reserved for those with physiologiccompromise such that treatment after birth is notfeasible.

Cross-References

▶Anatomy of the Infant and Child▶Congenital Airway Malformations▶Congenital Diaphragmatic Hernia▶Embryology of Congenital Malformations▶Epidemiology of Congenital Malformations

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