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Eur J Cardiothorac Surg 2003;24:703-711
© 2003 Elsevier Science NL
a Department of Pediatric Surgery, Landes-Kinderklinik Linz, Krankenhausstr. 26, A-4020 Linz, Austria
b Department of Clinical Radiology, University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna, Austria
c Department of Prenatal Diagnosis and Treatment, University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna, Austria
d Division of Pediatric Surgery, University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna, Austria
Received 7 January 2003; received in revised form 4 August 2003; accepted 6 August 2003.
* Corresponding author. Tel.: +43-1-732-6923; fax: +43-1-732-1109
e-mail: wolfgang.pumberger{at}gespag.at
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Abstract |
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 Top Abstract 1. Introduction2. Material and methods3. Results4. Discussion5. ConclusionsReferences |
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Key Words: Prenatal ultrasound diagnosis • Congenital lung malformations • Spontaneous regression • Postpartum multi-slice CT scan • Thoracic surgery
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1. Introduction |
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TopAbstract1. Introduction2. Material and methods3. Results4. Discussion5. ConclusionsReferences |
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A wide range of questions have been raised concerning nomenclature, embryology, pathology, reliable US features, prognostic indicators, spontaneous regression, hidden mortality, treatment options, and likely reasons for surgical intervention. The aims of the present study were to address all these aspects in an unselected regional study population and to determine the outcome of treatment in CLM. Many of these issues will be object of the counseling of parents and in planning treatment.
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2. Material and methods |
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TopAbstract1. Introduction2. Material and methods3. Results4. Discussion5. ConclusionsReferences |
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2.1. Prenatal diagnosis
Prenatal sonograms were obtained, starting at different stages of pregnancy, using commercially available real-time equipment (mainly a Toshiba PowerStation, SSA-380 A [Otawara, Japan]; 3.5-, 5.0- and 7.5-MHz sector-array transducer). Follow-up sonograms were repeated every 2–4 weeks until delivery to monitor location, size, sonographic appearance, and associated mass effects. Color-Doppler US examination was performed to demonstrate anomalous blood flow from the aorta to the CLM. A complete survey of other field organs was performed to rule out other structural anomalies.
Fetal karyotype analysis was obtained by amniocentesis or chorionic villus sampling in all cases except when the parents rejected the investigations.
2.2. In utero treatment
Termination of pregnancy was offered in the case of severe associated malformations. Fetuses that became symptomatic in utero (e.g., development of hydrops and/or hydrothorax, enlargement of cysts, mediastinal shift or polyhydramnios) underwent different types of in utero treatment (e.g., serial therapeutic amniocentesis, serial puncture of hydrothorax or cysts) as well as induction of preterm delivery.
2.3. Postpartum evaluation
In all live-born infants anterior–posterior and lateral radiographs of the chest were taken immediately after birth, and were evaluated for the presence of midline shift or mass effects, hyperinflation, cystic areas, subtle irregular hyperlucency, or soft tissue opacity.
Computerized tomography (CT) studies of the thorax were performed in the first month of life mainly using a multi-slice CT scanner, MSCT Volume Zoom, Siemens (Erlangen, Germany) with a low-dose protocol ([80 kV, 20 mAs], 4x1 mm collimation, 3 mm axial reconstruction, and 5 mm coronal reconstruction). Intravenous contrast medium (2 ml/kg with an 8 to 10-s delay) was used in the majority of cases, particularly to evaluate anomalous systemic feeding vessels.
2.4. Surgery
Selection of patients for surgical treatment depended on postpartum respiratory distress and/or achievement of patients' clinical stabilization, as well as on postnatal CT results. Surgical procedures included sequesterectomy, lobectomy, segmentectomy, and non-anatomic resection. CLM with a detectable anomalous systemic blood supply received an early planned thoracotomy. The other asymptomatic patients were followed up conservatively and operated on within the first year of life if the lesion was shown to persist on repeat CT scans.
2.5. Final diagnosis and follow-up
The prenatal sonograms, postnatal chest radiographs, and CT scans were reviewed in each case and correlated with postnatal clinical signs and symptoms and findings from surgical or pathological results, including postmortem findings.
Patients were divided into six groups based on prenatal US findings, in utero course, postpartum presentation and treatment of the lesion (Table 1) (1 = termination of pregnancy or fetal demise; 2 = complicated intrauterine course; 3 = confirmed spontaneous regression; 4 = suggested regression with postpartum persistent lesion; 5 = continuously detectable malformations; 6 = wrong diagnoses).
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3. Results |
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TopAbstract1. Introduction2. Material and methods3. Results4. Discussion5. ConclusionsReferences |
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Twenty-five cases (
71%) were diagnosed prior to 24 weeks and were therefore eligible for elective termination of pregnancy. Twenty-four of the 29 live-born infants (80%) were largely asymptomatic at birth and could be subjected to a staged diagnostic work-up. The chromosomal analysis was normal in all infants (n=27), and none of the eight infants whose parents had refused antenatal chromosomal investigation revealed postpartum evidence of chromosomal anomalies.
Apart from the patients of group 1 (see Table 2), there were only two minor associated malformations (e.g., chorioid plexus cyst, mitral valve insufficiency). In particular, we failed to detect major cardiac anomalies.
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3.2. Group 2 (n=4)
Four fetuses became symptomatic in utero when sequential scanning revealed the development and progression of hydrops, hydrothorax, mediastinal shift, polyhydramnios, or enlargement of cysts at a mean gestational age of 24 weeks gestation (range, 22–27 weeks). The absence of other structural or chromosomal anomalies prompted the decision to bear the children.
Serial therapeutic amniocenteses were performed in three cases, and two fetuses received serial puncture of either the hydrothorax or intrapulmonary cysts (Table 3). Despite these interventions rapid re-accumulation of fluid and/or progression of negative mass effects led to a delivery before term in three cases at a mean gestational age of 33.7 weeks (mean birth weight 2462 g). The infants experienced respiratory distress and required preoperative treatment in the intensive care unit over a period from 2 days to 4 weeks (Table 3).
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The duration of postoperative hospitalization ranged from 9 to 55 days (mean period 26 days). Patient number 3 developed a mild degree of bronchopulmonary dysplasia postoperatively, whereas patient number 4 suffers from recurrent bronchiolitis. Follow-up with multi-slice CT revealed several small residual cystic areas in the preserved apical portions of the left lower lobe.
3.3. Groups 3 and 4 (n=11)
In these patients, serial antenatal US examinations towards the end of pregnancy (36–38 weeks gestation) were considered to demonstrate spontaneous resolution of CLM. Five infants were shown to have a persistent lesion which was not demonstrable on radiographs but could be well depicted on multi-slice CT scans. Resolution without sequelae was confirmed only in six infants on postpartum US, radiographs and CT scans. Depiction of systemic anomalous vascular supply on a CT scan in two infants correlated with the intraoperative findings.
Infants with persistent CLM underwent uneventful resection of the lesion (lobectomy [n=2], segmentectomy [n=1], sequesterectomy [n=2]) at a mean age of 7.4 months of life (range, 4–12 months). Histological evaluation established a final diagnosis of PS in four cases (two EPS, one intrapulmonary sequestration [IPS], and one IPS/CAM II hybrid type) and CAM I in one.
3.4. Group 5 (n=11)
In 11 fetuses, CLM were continuously demonstrated during pregnancy without noteworthy changes in size (<25%) and/or structure, whereas four infants revealed an impressive resolution of the mediastinal shift. All infants were asymptomatic after birth and could be monitored in a normal postnatal care unit.
The infants remained asymptomatic until surgery which was performed uneventfully in nine children at a mean age of 3.8 months (range, 1–11 months). Surgery included three lobectomies, three segmental resections, and three sequesterectomies. Intraoperative findings of anomalous systemic vascular supply correlated with the results from prenatal US (n=3) and postpartum performed CT scans (n=6). Histological evaluation established a final diagnosis of two EPS cases, five hybrid type lesions (CAM I/CLE [n=1], IPS/CAM II [n=3], and EPS/CAM II [n=1]), and two cases of CAM I.
Two infants with a postpartum confirmed diagnosis of a mild degree of CAM in the right lower lobe have not been operated on so far. The children are awaiting a final decision, as repeated CT scans showed partial resolution of the lesion during the first months of life.
3.5. Group 6 (n=3)
In three patients, the primary antenatal diagnosis of either CAM (n=2) or PS (n=1) had to be corrected during the subsequent diagnostic and therapeutic work-up (see Table 1). The boy with an intrapulmonary bronchogenic cyst was operated on only at the age of 6 years, when he experienced several attacks of serious respiratory infection due to an inflamed intrapulmonary bronchogenic cyst.
In summary, surgical procedures were performed on 18 infants with postpartum demonstrable CLM. Tables 4 and 5 refer to the types of surgical procedure and to the type of lesion. Concerning the location of CLM, there was a clear preponderance of the left side and the lower lobes (Tables 4 and 5). From a pathological point of view, there is a preponderance of hybrid type lesions (six of our 18 operated patients, 33%) and a remarkable equal distribution between IPS and EPS (see Table 5). The hybrid lesion between CAM I and congenital lobar emphysema (CLE) was interpreted as a singular case.
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4. Discussion |
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TopAbstract1. Introduction2. Material and methods3. Results4. Discussion5. ConclusionsReferences |
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Until the last decade, CLM were considered to be rare and to signify an enormous risk of fetal demise or life-threatening respiratory compromise after birth [2,6]. About 14% of fetuses with CAM were stillborn, while 80% were estimated to present with severe cardio-respiratory compromise immediately after birth. In 90% the condition was discovered in the first year of life (70% in the first week) [3,6,7]. Conversely, PS was diagnosed in up to 30% only during investigation of another anomaly (e.g., CDH, cardiac failure) [7–9].
Nowadays, prenatal detected CLM have been proven to be entirely different in many cases from previous concepts of pathogenesis, diagnosis and treatment. Postpartum, the majority of antenatally diagnosed CLM are shown to present completely asymptomatic [3–5,8,10–13]. Later in childhood and adult life, infants with unrecognized CLM may seek medical treatment for progressive respiratory distress, failure to thrive, cardiac failure or recurrent infection of the respiratory tract. Malignant transformation (e.g., pulmonary blastoma, rhabdomyosarcoma) in CAM has been reported in singular cases only [3,7,10].
4.1. Nomenclature and classification
Despite several attempts to do a complete reappraisal the nomenclature and classification of CLM are still ambiguous. Previously applied classification systems mix a number of variable characteristics (e.g., gross appearance, histopathology, sonographic features, radiography, CT scanning, MRI, and surgical findings). Additionally, different terms were used inconsistently in the ante- and postnatal periods and are used to describe overlapping abnormalities [1,3,10,11,14].
CLM are shown to represent a continuum of anomalies of fetal lung development. The term ‘bronchopulmonary-foregut malformation’, introduced by Gerle et al. [15], takes into account the close communication between the respiratory and the gastrointestinal tract during the first weeks of the embryological development. In 1987, Clements and Warner [16] published the classification system of ‘pulmonary malinosculation’ which refers to an abnormal congenital connection or opening of one or more of the bronchopulmonary vascular complex. Conversely, Bush [17] recently proposed a more descriptive classification system while avoiding embryologic speculation.
4.2. Hybrid type lesion
Clinicians still continue to differentiate between CAM and PS on the ground of symptomatologic clinical signs and findings from radiology, surgery and pathology [4,7,18]. Contrary to this classical strict distinction, a final diagnosis of a mixed or hybrid type lesion (e.g., PS associated with CAM, predominantly CAM type II in PS) could be made postpartum in up to 15–40% of CLM cases [3,4,9,18]. These lesions were shown to have an anomalous systemic vessel directly arising from the aorta, whereas histopathological evaluation revealed features of both CAM and PS. Furthermore, the presumed preponderance of intralobar PS (IPS) over extralobar PS (EPS) should rightly be corrected to a nearly equal distribution of IPS and EPS.
4.3. Antenatal ultrasonography
Antenatal US includes direct visual assessment of the thoracic lesion and following mass effects (e.g., pleural effusion, ascites, hydrops fetalis); it also enables the investigator to demonstrate associated anomalies of the fetus [2,4,10,12,13]. Early detection of CLM provides increasing information about the natural history of the disease (e.g., course, regression, side-effects) and prevents irreversible harm to the fetus in cases eligible for in utero treatment [4,10,12].
With improved US resolution and better comprehension of sonographic findings, a number of different sonographic features of CLM were identified. Thus, the accuracy in classifying these lesions on prenatal US has increased from 60 to 90% [4,13,14,18–20].
There is a wide range of sonographic appearances in CLM from subtle to markedly increased uniform echogenicity to lesions containing large echofree areas [14,20]. Microcystic lesions appear more solid due to fine interfaces with the US beam that might create an almost homogenous appearance [14,20].
CLM are predominantly located in the posterior basal segments of lower lobes and only rarely affect middle or upper lobes. Bilateral uniformly increased echogenicity (2%) has a poor outlook, and some bilateral cases, previously called type III CAM, may in fact have been laryngo-tracheal atresia [14]. Size and volume of CLM as well as associated lung hypoplasia can be evaluated only in a semiquantitative fashion (e.g., computer-assisted planimetry, volumetry, and prenatal ultrafast-MRI) [4,12]. Crombleholme et al. [21] hypothesize that the volume of a CLM could predict whether hydrops would develop.
Color-Doppler US examination can show an anomalous vessel to arise from the thoracic or abdominal aorta and to ramify within the separated lung parenchyma [4,14,20].
Pathophysiological effects on the fetus and the mother (e.g., placenta edema, polyhydramnios) can be demonstrated on prenatal US [12,14,20]. Development of non-immune hydrops fetalis (NIHF) (e.g., skin edema, pleural effusion, ascites, and pericardial effusion) represents one of the most harmful situations during pregnancy with poor outcome for the fetus [2,4]. However, isolated fluid accumulations, such as ascites or pleural effusion only, can occur and are associated with a far better prognosis than in NIHF-complex [1,8,13]. Resolution of mediastinal shift or pleural effusion can be observed independently from the course of the lesion itself.
4.4. Spontaneous regression of CLM
Sequential antenatal US may reveal changes both in size and structure of a lesion. From a sonographic point of view CLM could (1) show progression in size and/or development of NIHF (6%); (2) remain unchanged in size and sonographic appearance throughout the remainder of the pregnancy; and (3) show decrease in size or even complete disappearance (30%) [14]. The timing of this phenomenon of ‘regression’ is variable but tends to be in the mid-third trimester, usually at 32–34 weeks gestation. Several factors appear to be important for a loss of sonographic conspicuity (e.g., loss of fluid/tissue interfaces, resolution of the cystic parts, transient obstruction, acute cessation of systemic blood flow, and torsion of the sequestration) [3,4,11,12,14,19].
Suspected resolution of the US appearances in utero, however, does not necessarily imply complete resolution of the primary pathology. Our study demonstrates that significant abnormalities are shown to persist and thus supports the importance of thorough application of postnatal imaging studies. There exist no studies concerning with the possibility of continuous postpartum regression during the first years of life.
4.5. Differential diagnosis of CLM
A number of pathological entities should be considered in the differential diagnosis of CLM (e.g., congenital diaphragmatic hernia, CLE, tracheal atresia, bronchial atresia, bronchogenic cysts, and gastrointestinal duplication cysts) [2,3,12–14]. Although prenatal US is becoming increasingly sophisticated, diagnostic errors are possible, particularly during the early second trimester. Fetal ultrafast-MRI might provide important information in exceptional cases and might be helpful in establishing a correct differential diagnosis [3,5,13,22–24].
4.6. Timing of treatment in CLM
The goals of antenatal treatment should be to prevent fetal demise and/or irreversible harm to lung development which would result in a disastrous postpartum situation. In our experience intrauterine treatment (e.g., puncture of pleural effusion or cysts, fetal surgery) or urgent postpartum surgical treatment should be recommended only in highly selected fetuses (i.e. progression of mass effects) since the large majority of CLM may be expected to present postpartum without any serious clinical signs and symptoms [4,12].
The aims of postnatal treatment are to improve and stabilize the clinical condition of the child and to prevent sudden lethal deterioration or development of complications (e.g., progressive respiratory symptoms, infection, and malignant transformation) [4,13,14]. The management of completely asymptomatic patients with suggested decrease in size of the lesion is a controversial issue. Some authors advocate close clinical observation unless symptoms develop, whereas others favor elective resection within the first months of life in every case because of the risks of recurrent infection or malignant transformation [1,7,8,14,22].
4.7. Applied surgical procedures in CLM
In cases with a confirmed diagnosis of CLM an elective removal of PS and CAM should be performed before complications occur. EPS are managed with simple resection of the mass alone. In IPS, management presents more of a challenge, particularly when the patient has suffered repeated periods of infection which may produce dense, vascular adhesions and obliterate normal tissue planes. Lobectomy or segmentectomy will be the best suited procedures in most cases of IPS and CAM (Table 4). The argument for lobectomy is that an elective resection of a single lobe in an infant is very well tolerated [1,4,7–9,11]. Conversely, many reports indicate that methods of partial lobar resection (e.g., segmentectomy and non-anatomic resection) have not been as free of complications as complete lobectomy (e.g., persistent air leak, postoperative infection, higher incidence of recurrence) [4,7,11]. However, segmentectomy of the basal segments of the left lower lobe can be performed even in small infants. Non-anatomic resection has been applied in singular cases to preserve at least parts of a completely involved lung; otherwise surgery could have resulted in pneumonectomy.
The fact that surgery of CLM in the early infancy is well tolerated as well as the possibility of malignant transformation argues against recently reported interventional embolization of the anomalous vessel which also requires general anesthesia and could be difficult to perform in children [12,25].
4.8. Anomalous vascular supply to CLM
All applied surgical procedures must take into account the probabilities of anomalies of the vascular supply to the lung and/or the malformation. The most common vascular anomalies in CLM concern the systemic arterial supply in PS and CAM/PS hybrid type arising from the descending thoracic, abdominal aorta and its major branches. Preoperative depiction of anomalous systemic vascular supply makes surgery, which is often a rather simple procedure, less hazardous. The aberrant arteries may be extremely retractile and are often friable. Hence, at surgery the vessels and the inferior pulmonary ligament must be suture-ligated with care. Otherwise, the vessels can retract into the mediastinum or even into the abdomen and continue to bleed.
Major anomalies of the pulmonary artery branches could be predominantly expected in CAM and IPS. To recognize these varieties could be of great importance if segmentectomy or organ-sparing surgery is intended. Perception of an anomalous venous return during surgery is important because an unnoticed mismatch venous return of the entire right lung could lead to a catastrophic intraoperative situation (e.g., lung infarction) [8,12,18,24].
Prenatal and postpartum US, CT scanning, and MR imaging are non-invasive techniques that have been reported during the last decade to be well suited for evaluating anomalous vascular supply [4,18,24]. Thus, invasive techniques such as arteriography are reserved for exceptional cases.
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5. Conclusions |
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TopAbstract1. Introduction2. Material and methods3. Results4. Discussion5. ConclusionsReferences |
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References |
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TopAbstract1. Introduction2. Material and methods3. Results4. Discussion5. ConclusionsReferences |
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