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Eur J Cardiothorac Surg 2005;27:45-52
© 2005 Elsevier Science NL
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Department of Paediatric Cardio Thoracic Surgery, Royal Hospital for Sick Children, Dalnair Street, Glasgow G3 8SJ, Scotland, UK
Received 24 March 2004; received in revised form 1 October 2004; accepted 6 October 2004.
* Corresponding author. Tel.: +44 141 201 0269 (E-mail: jim.pollock{at}yorkhill.scot.nhs.uk).
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Abstract |
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 Top Abstract 1. Introduction2. Materials and methods3. Results4. Discussion5. ConclusionReferences |
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Key Words: Congenital cystic adenomatoid malformation • Congenital lobar emphysema • Bronchogenic cyst • Lung resection • Sequestration
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1. Introduction |
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TopAbstract1. Introduction2. Materials and methods3. Results4. Discussion5. ConclusionReferences |
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2. Materials and methods |
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TopAbstract1. Introduction2. Materials and methods3. Results4. Discussion5. ConclusionReferences |
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2.1. Associated anomalies
Associated cardiac anomalies included patent ductus arteriosus (1) and atrial setal defect (2). Non-cardiac anomalies occurred in four patients (Wilms tumour—1; Down's syndrome—1; duodenal and jejunal duplication cysts—1; polycystic kidney—1). Three patients had bronchial asthma and one patient had associated acute lymphatic leukemia. All patients had chest radiography. Diagnostic studies included CT scan (22), MRI (7), arteriography (1) and bronchoscopy (5).
2.2. Type of resection
Eight emergency resections were performed (CCAM 4; CLE 3; Bronchogenic cyst 1). Surgical procedures included 24 lobectomies, one right middle lobectomy with a wedge resection of the right lower lobe, one completion right lower lobectomy, four sequestrectomies, one mediastinal mass excision and one wedge resection for a bronchogenic cyst. Surgical access was by right or left thoracotomy in most patients, and rethoracotomy in one. All resected specimens were submitted for histopathology.
2.3. Congenital cystic adenomatoid malformation (n=13)
There were four neonates and six infants. Mean age at surgery was 18.2 months (range 7 days to 9 years). Nine patients had recurrent pneumonias. Nine antenatally diagnosed patients underwent resection within the first year of life. Four neonates (mean age 11 days) presenting with moderate (n=2), or severe respiratory distress necessitating preoperative ventilation (n=2), required an emergency lobectomy. The mean age of the five infants was 4.7 months.
Surgical treatment for congenital cystic adenomatoid malformation consisted of right upper lobectomy (2), right middle lobectomy (2), right lower lobectomy (3), left upper lobectomy (3), and left lower lobectomy (2). One patient underwent a right middle lobectomy and a wedge resection of the right lower lobe for extensive CCAM, but developed a prolonged air leak postoperatively and required a completion right lower lobectomy.
Histopathologically, eight specimens had Stocker Type 1 and five had Stocker Type 2 CCAM. No Type 3 lesions were seen. Three out of 13 patients had mild respiratory symptoms at follow up (lymphatic leukemia—1; recurrent respiratory infection—1, bronchial asthma—1).
2.4. Congenital lobar emphysema (n=9)
There were three neonates and four infants. Mean age at surgery was 9.7 months (range 3 days to 3 years). Cases of lobar hyperinflation secondary to intraluminal or extrinsic obstruction were excluded. Three neonates had respiratory distress and marked mediastinal shift (Fig. 1), requiring an emergency lobectomy. One patient required ventilation preoperatively. Bronchoscopy was performed in four children to rule out intrinsic obstruction. A pulmonary angiogram was done in one patient to rule out extrinsic vascular compression. Surgical treatment consisted of right upper lobectomy (1), right middle lobectomy (4), and left upper lobectomy (4). None of these patients had pulmonary hypoplasia. Two out of nine patients (with bronchial asthma) had mild wheeze at long-term follow-up.
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2.6. Bronchogenic (n=2) and enteric cysts (n=1)
Three patients underwent resection for bronchogenic/enteric cysts. Mean age at surgery was 26.3 months (range 3 days to 51 months). One neonate aged 3 days (diagnosed antenatally to have CCAM) required excision of a mediastinal mass due to pressure effects from a large enteric cyst in the right paravertebral gutter. This neonate had associated duodenal and jejunal cysts.
Surgery for bronchogenic cysts in the two children with recurrent infections consisted of right middle lobectomy (1) and wedge resection (1). Histopathologically, these cysts were lined by squamous epithelium. All patients were asymptomatic at follow up.
2.7. Antenatal diagnosis
Fifteen of the 31 patients who underwent resection, had lung lesions diagnosed on antenatal ultrasound. This included nine congenital cystic adenomatoid malformations (all marocystic), five sequestrations and one enteric cyst, which was antenatally diagnosed as a congenital cystic adenomatoid malformation. In addition, antenatal ultrasound detected lesions in six fetuses, which regressed by the end of the pregnancy. Foetuses with an antenatal diagnosis were followed up with sonograms at regular intervals until delivery to monitor location, size, and associated mass effects.
Following the initial diagnosis on antenatal ultrasound, the in utero course of these patients evolved as described. In ten patients, antenatal ultrasound at the end of pregnancy was considered to demonstrate resolution of the anomaly. Five infants with CCAM were shown to have a persistent lesion, which was not demonstrable on radiographs but could be depicted on postpartum multi-slice CT scans. The five sequestration patients were shown to have persistent lesions on both chest radiographs and CT scan.
In six patients, serial antenatal sonograms towards the end of pregnancy demonstrated spontaneous resolution of the malformation, which was confirmed by postpartum ultrasound, radiographs and CT scans. Serial therapeutic amniocenteses were performed in three fetuses with polyhydramnios. Re-accumulation of fluid occurred in one foetus while the others improved. All patients in this group underwent emergent resection.
In two fetuses, the malformation remained stable and neither progressed nor regressed. There were no associated mass effects with these lesions. One patient diagnosed to have CCAM on antenatal ultrasound, was shown to have an enteric cyst on postoperative histopathology.
There was no evidence of progression of hydrops, mediastinal shift, or cyst enlargement in any of the foetuses on sequential scanning. No foetuses in this series had other structural anomalies detected on ultrasound. No pregnancy was terminated. There were no instances of foetal demise.
Of the 15 patients diagnosed antenatally, five neonates underwent emergency resection (4—congenital cystic adenomatoid malformations; 1—enteric cyst). All four patients with congenital cystic adenomatoid malformation (including one patient with multilobar CCAM) who underwent an emergent resection had Stocker type 2 features on histopathology. This included the patient with multilobar CCAM. Ten out of 15 (66.67%) antenatally diagnosed malformations (including all five sequestration patients) required only elective resections later in life. Nine out of ten cases of antenatally diagnosed CCAM were confirmed postnatally as having a CCAM. The other neonate had an enteric cyst.
2.8. Statistics
Data are presented as means and range.
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3. Results |
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TopAbstract1. Introduction2. Materials and methods3. Results4. Discussion5. ConclusionReferences |
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4. Discussion |
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TopAbstract1. Introduction2. Materials and methods3. Results4. Discussion5. ConclusionReferences |
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4.1. Congenital cystic adenomatoid malformation
Congenital cystic adenomatoid malformation (Fig. 3a–c) results from a cessation of bronchial maturation and concomitant overgrowth of mesenchymal elements, which produce the adenomatoid appearance [1].
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Conran and Stocker [2] demonstrated the coexistence of a sequestration in up to 50% of cases. None of our patients had an associated sequestration. Surgical resection results in good symptom relief and long-term outcome. Prognosis is, however, bad for those with bilobar and bilateral lesions, and those with pulmonary hypoplasia [3]. Only one patient in our series had bilobar CCAM.
In our experience, cases with more extensive unilobar or bilobar congenital cystic adenomatoid malformation were the ones where serial therapeutic amniocentesis (n=3) was performed. These were also the neonates who presented with respiratory distress, needed urgent and more extensive resections (n=4) and showed Stocker type 2-lesions on histopathology. The others had a more stable intrauterine course, usually underwent elective resection and had better histopathological features. However, all of them had the macrocystic variant of CCAM on antenatal ultrasound, which tends to have a better prognosis.
Rhabdomyosarcoma and bronchio alveolar carcinoma are reported complications of CCAM. Increased cell proliferation, decreased apoptosis [4], and malignant transformation of the glandular component [5], have been cited as carcinogenic mechanisms in CCAM. Lobectomy is, therefore, safe effective, precludes air leaks and infections and completely removes potentially malignant tissue that might exist among the cystic lesions.
There is debate about the advisability of segmental resection versus lobectomy for CCAM. In infants with extensive CCAM, non-anatomic pulmonary resection has been promoted as a parenchymal sparing technique that permits preservation of normal pulmonary remnants, which then demonstrate the capacity for expansion, growth, and function. However, this can be complicated by prolonged air leaks and recurrent postoperative infections, necessitating repeat surgery and lobectomy, due to incomplete removal of abnormal lung tissue. This occurred in one of our patients. Some authors believe that the possibility of prolonged postoperative air leak should not discourage surgeons from attempting conservative resections whenever this proves feasible. However, the numbers have been small.
Impaired pulmonary function is uncommon unless more than one lobe is resected. Infants and children tolerate lobectomy well with compensatory lung growth so that total lung volume and gas exchange capacity return toward normal during somatic maturation. Long-term symptoms tend to occur in those with associated lung disorders like asthma. Preoperative pulmonary function tests may be especially beneficial in such patients as well as those with multilobar or bilateral involvement where more extensive resections may be anticipated.
Based on our experience, we would prefer to perform a lobectomy in those with extensive but unilobar involvement and those who undergo emergent resections. In those with mutilobar involvement, the extent and type of resection would be determined by the extent of lung involvement and the presence of associated disorders.
4.2. Congenital lobar emphysema
Congenital lobar emphysema (CLE) is a marked pulmonary hyperinflation state, usually involving the left upper and right middle lobes. The most constant pathological finding is cartilage deficiency resulting in bronchomalacia, and causing collapse on expiration followed by air-block hyperinflation. Some cases are associated with intraluminal bronchial obstruction that, by definition is not acquired by aspiration of a foreign body or mucus plugging, but is caused by abnormal mucosal folds, bronchial stenosis or kinking. CLE manifested as severe respiratory distress in three patients, and with wheezing, cough or recurrent chest infections in the six older children.
Chest radiograph and CT (Fig. 4), findings include hyperlucency (with scant pulmonary markings) of the involved lobe, herniation of the hyperinflated lobe to the opposite side with mediastinal shift and adjacent lobe collapse. The diaphragm on both sides may be displaced downward. CT shows stretched attenuated vessels in the emphysematous lobe. It is very important not to confuse CLE with a pneumothorax; an intercostal tube further increases respiratory distress.
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Neonates with CLE tolerate positive pressure ventilation poorly, and rapid thoracotomy may be necessary to relieve the compression of the remaining normal lung tissue. The surgeon should be, therefore, present at anaesthetic induction. At thoracotomy, the abnormal lobe usually herniates through the opened hemithorax white the remaining lung is atelectatic.
Even following lobectomy, children continue to have mild wheezing especially during respiratory infections. The children in our series who had postoperative symptoms were also asthmatic.
4.3. Sequestration
The frequency of intralobar to extralobar sequestration is about 3:1 [6]. In our series, however, the ratio was 1:2. An intralobar pulmonary sequestration is usually located in the posterior basilar region of the lower lobe, and presents as recurrent bouts of pneumonia or abscesses in the affected lobe. Extralobar sequestration is often found in the left posterior costophrenic angle. Symptoms are caused by left-to-right or left-to-left shunting causing high output failure, anatomic impingements, or associated anatomic defects. Ten percent remain asymptomatic and persist to adulthood [7].
Associated congenital abnormalities are common, occurring in up to 65% of cases. They include diaphragmatic hernias, pectus excavatum, foregut duplications, and congenital heart defects. The term ‘bronchopulmonary foregut malformation’ was introduced in reference to pulmonary sequestrations with a communication with the oesophagus or stomach, which may be an obliterated fibrous cord or a patent tract. A barium study is beneficial in such cases.
Preoperative delineation of the anomalous vasculature minimizes fatal outcomes from haemorrhage caused by accidental division of the systemic artery. The aberrant arteries may be extremely retractile and friable. They must be suture-ligated with care to prevent bleeding following retraction into the mediastinum or the abdomen. Retrograde aortography has been the traditional approach to diagnosing pulmonary sequestration especially in those cases with multiple arteries supplying the sequestration.
Helical CT [8] and colour Doppler sonography can delineate the feeding vessels non-invasively [9]. Contrast-enhanced magnetic resonance angiography has replaced the need for conventional angiography [10], by displaying the aberrant artery without flow or respiratory artefact. A reported limitation of MRI is that small anomalous vessels may not be detected.
Several authors have proposed conservative treatment for the majority of patients and reserved surgical intervention only in case of complications. Numerous reports have described serious complications arising from sequestrations, such as fungal infection [11], tuberculosis [12], fatal haemoptysis [13], massive hemothorax [14], cardiovascular problems [15], benign tumors [16], and even malignant degeneration [17]. It has, therefore, been our policy to resect sequestrations to establish a diagnosis, and prevent serious complications.
Sequestrectomy for ELS is fairly straightforward, as the malformation is well separated from the normal lung by its own pleural envelope. In intralobar sequestration, inflammatory changes from previous infections can produce dense, vascular adhesions, obliterate the intersegmental plane and make intraoperative identification of the aberrant blood supply difficult. Lobectomy, therefore, is the treatment of choice. Early resection prior to the development of chronic inflammation may permit a parenchymal-sparing resection.
4.4. Bronchogenic cysts
Bronchogenic cysts are primitive foregut remnants that originate from embryonic bud tissue before the bronchi were formed. They present as respiratory distress (mediastinal cysts) in neonates, or as pulmonary sepsis (space occupying and infected parenchymal cysts) in older infants. The most common presenting symptoms are cough, stridor or wheezing due to airway compression.
Bronchogenic (Fig. 5a and b) and enteric (Fig. 5c) cysts occurred in three patients in our series. Two of the resected cysts were lined with squamous epithelium, presumably due to the recurrent infection. Rupture into pleural space, compression atelectasis, infection, neoplastic change, and cyst haemorrhage are potential complications, leading to more extensive resections and increased operative risk. Maier and associates classified bronchogenic cysts into five groups by location: paratracheal, and miscellaneous including pericardial, cervical, subcutaneous and abdominal sites. Up to 1/3 of bronchogenic cysts remain asymptomatic.
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Simple cysts can usually be resected without loss of any significant functional lung tissue unless long-term compression atelectasis or superimposed infections have caused adjacent parenchymal abnormalities. Barium studies can demonstrate abnormal communication of the respiratory tract with the esophagus or stomach.
4.5. Video assisted thoracoscopic surgery
Video assisted thoracoscopy minimizes access trauma and postoperative pain and has been used to resect these lesions. Serious and life threatening blood loss may result from pulmonary hilar dissection. Other complications include conversion to thoracotomy due to adhesions to vital structures and intraoperative injuries.
4.6. Antenatal diagnosis
Prenatal sonographic now makes it possible to define the natural history of congenital lung malformations, determine the pathophysiologic features affecting clinical outcome, and formulate management based on prognosis.
4.7. CCAM classification
Adzick [18] described two types of CCAM by gross anatomy, ultrasonographic findings, and prognosis–microcystic lesions (cysts<5mm; solid appearance) are often associated with foetal hydrops and have a poor prognosis. Macrocystic lesions (single or multiple cysts>5mm) have a more favourable prognosis.
4.8. Pathophysiology
Pathophysiological effects on the fetus and the mother can be demonstrated on prenatal ultrasound [19]. Development of hydrops (skin edema, pleural effusion, ascites, and pericardial effusion) is associated with poor foetal outcome [20]. Vena caval, oesophageal and cardiac compression are responsible for fetal hydrops with ascites pleural and pericardial effusions, and skin and scalp edema. Fetal hydrops causes placentomegaly and endothelial injury occurs in the poorly perfused megaplacental tissue with release of vasoactive factors. Expanding congenital intrathoracic lesions can cause pulmonary hypoplasia due to compression of the developing lung. The hypoplastic lung is inadequate for normal gas exchange owing to an insufficient number of airway and vascular branches and additional vasomuscular hypertrophy. This can result in pulmonary hypertension and persistent fetal circulation.
4.9. Prognostic features and counselling
Prognostic features that require consideration for prenatal counseling include the size and type of mass, laterality, progression or regression of the mass, cardiac deviation, hydrops, polyhydramnios, pulmonary hypoplasia, type 3 lesions and associated anomalies. Large, bilateral and microcystic lesions tend to have a more adverse prognosis.
4.10. Natural history
The natural history of these lung masses is variable. From a sonographic standpoint congenital malformations could (1) show progression in size and/or development of hydrops; (2) remain stable throughout pregnancy; and (3) decrease in size or disappear. The timing of this phenomenon of ‘regression’ is variable but tends to be in the mid-third trimester, usually at 32–34 weeks gestation.
4.11. Accuracy of prenatal detection
The accuracy in classifying these lesions on prenatal ultrasound has increased significantly. However, although prenatal ultrasound is becoming increasingly sophisticated, diagnostic errors are possible. Sequestration can be difficult to confirm. The anomalous arterial supply can be difficult to visualize despite color doppler, owing to the small size of the vessel and its proximity to the heart and prevertebral vessels. The prenatal diagnosis of congenital lobar emphysema is only rarely reported in the literature and the sonographic features have not been well characterized. Problems of diagnostic accuracy and resolution may render counseling difficult. More recently antenatal magnetic resonance imaging has provided further information on the nature of these lesions and helped to differentiate them from extrathoracic abnormalities such as congenital diaphragmatic hernia, which is important in parental counseling.
4.12. Foetal intervention
The goals of antenatal treatment are to prevent fetal demise and/or irreversible lung injury. Symptomatic treatment of polyhydramnios includes, repetitive amniocentesis, indomethacin therapy, and video-endoscopic or ultrasono-guided placement of a thoracoamniotic shunt [20].
The finding that fetuses with hydrops are at high risk for fetal or neonatal demise without intervention led to fetal lobectomy. Pioneering work by Harrison and Adzick suggested removal of lesions through a hysterotomy and thoracotomy, but prevention of premature contractions and premature labor remain in an important problem.
Foetuses with CCAM but without hydrops have a good chance for survival with maternal transport, planned delivery, and immediate neonatal resuscitation and surgery. Whether fetal surgery in these cases would be beneficial is difficult to say given the possibility of spontaneous regression. Fetal surgery is currently reserved for only those fetuses with hydrops and a uniformly fatal outcome.
4.13. Postnatal evaluation
Prenatal lesions on sonograms can resolve partially or completely on sonograms performed late in gestation. Suspected resolution of the ultrasound appearances in utero, however, does not necessarily imply complete resolution of the primary pathology. Normal radiographic findings do not preclude persistence on CT scan. Hence, all infants with an antenatal diagnosis of congenital lung malformations require postnatal evaluation based on chest radiographs and CT even if the lesions apparently disappear during pregnancy or if they are asymptomatic.
4.14. Postnatal surgery
Selection of patients for surgery depends on postpartum respiratory distress, as well as on postnatal radiology. Symptomatic patients and those in respiratory distress undergo surgical resection. Neonatal pulmonary surgery is safe, provided no other life-threatening problems are involved.
4.15. Asymptomatic patients
The management of asymptomatic patients is controversial. Some authors advocate close observation, whereas others favor elective resection in every case because of the risks of recurrent infection or malignant transformation. Early surgery reduces complication related morbidity and parental anxiety. Besides, alveolar multiplication continues in the first years of life. Compensatory lung growth after resection is, therefore, possible in infants, but not in adults. Patients with CCAM, bronchogenic cysts and intralobar sequestration frequently had multiple abscesses in the resected lobes, consequent to the recurrent respiratory infections. Early diagnosis and surgery precludes the formation of abscesses and adhesions, if segmental resection is to be considered in these patients. We, therefore, believe that the risks of pulmonary compression, infection and malignant degeneration make surgical exploration imperative, even in asymptomatic patients.
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5. Conclusion |
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TopAbstract1. Introduction2. Materials and methods3. Results4. Discussion5. ConclusionReferences |
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In older children, the technical problems of anaesthesia, surgery, and postoperative care reduce. This has to be balanced against the ability of infants and very young children to replace lost lung parenchyma. The risk of pulmonary compression, infection and malignant degeneration makes surgical exploration imperative, even in asymptomatic patients.
Lobectomy is our treatment of choice but segmental resection is an important option and should be considered when larger resections may not be tolerated. Surgical resection results in symptomatic relief and long-term outcome, except for the cases with pulmonary hypoplasia, and those with associated disorders. Emergency surgery in patients with severe respiratory distress is sometimes necessary to achieve an optimum outcome.
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References |
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TopAbstract1. Introduction2. Materials and methods3. Results4. Discussion5. ConclusionReferences |
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