Surgical Management of Lung Bud Anomalies: Lobar Emphysema, Bronchogenic Cyst, Cystic Adenomatoid Malformation, and Intralobar Pulmonary Sequestration

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1 Surgical Management of Lung Bud Anomalies: Lobar Emphysema, Bronchogenic Cyst, Cystic Adenomatoid Malformation, and Intralobar Pulmonary Sequestration J. Alex Haller, Jr., M.D., E. S. Golladay, M.D., Laurens R. Pickard, M.D., Joseph J. Tepas,, M.D., Nicholas A. Shorter, A.M., and Dennis W. Shermeta, M.D. ABSTRACT Recently we saw 9 infants with lifethreatening respiratory distress. Four patients had bronchogenic cyst, 2 had cystic adenomatoid malformation, and 9 had congenital lobar emphysema. Another group of 4 older children had recurrent infection and hemodynamic abnormalities, which responded to operative intervention. Each child required an appropriate resection following definitive diagnosis. These lesions represent a spectrum of closely related anomalies that arise during an early stage of embryonic lung bud maturation. Bronchoscopy is rarely useful, but special roentgenographic studies, including perfusion scans and arteriography, are usually diagnostic. Our operative experience is used to emphasize the urgency of precise diagnosis and surgical management of this poorly recognized clinical syndrome. Both life-threatening respiratory distress in newborn infants and recurrent pulmonary infections in older children can result from lung bud anomalies, which include congenital lobar emphysema, bronchogenic cyst, cystic adenomatoid malformation, and intralobar pulmonary sequestration (Fig ). One purpose of this report is to emphasize the close relationship of these lesions in terms of embryology and clinical presentation [2. Another is to recognize two distinct periods in childhood when surgical intervention could be required-in newborn babies when there are intrathoracic From the Division of Pediatric Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD. We would like to thank Mrs. Marcy Shackelford for preparing this manuscript. Presented at the Twenty-fifth Annual Meeting of the Southern Thoracic Surgical Association, Nov 2-4, 978, Marco Island, FL. Address reprint requests to Dr. Haller, Department of Surgery, The Johns Hopkins Hospital, Baltimore, MD tension problems [7] and in older children who have chronic recurrent pulmonary infection. Clinical Material We reviewed our experience with infants and children with pulmonary abnormalities who were seen between July, 969, and March, 978. There were 9 patients with congenital lobar emphysema, 4 with bronchogenic cyst, 2 with cystic adenomatoid malformation, and 4 with intralobar pulmonary sequestration. They ranged from birth to 7 years old. The following case reports illustrate the pathophysiology of each of these anomalies and emphasize the typical clinical signs and symptoms of each. Congenital Lobar Emphysema Of our 9 patients with congenital lobar emphysema, 5 were boys and 4 were girls; 8 were white and was black. In 7 the symptoms were evident at birth or during the first few days of life. The oldest patient was 2 years old. The symptoms, the location of the disease, and the resections performed are summarized in Table. Long-term follow-up was obtained on all patients up to 9 years postoperatively. The first case report illustrates the problem of respiratory distress in the newborn period and the second defines management of this anomaly in an older child. PATIENT. A white female infant, weighing 5,80 gm, was born to a 30-year-old woman following an uncomplicated pregnancy. The baby was vigorous at birth, but had excessive oropharyngeal secretions. During the first 24 hours, progressive respiratory distress developed, with sternal retractions, grunting, and tachypnea. The infant could not take oral feedings. No cyanosis or cardiac murmurs were noted. Blood gases were normal. Chest roent by J. Alex Haller, Jr.

2 34 The Annals of Thoracic Surgery Vol 28 No July 979 \ / Esophagus Artery from aorta Fig I. Lung bud anomalies. Table. Summary of Data Relating to Congenital Lobar Emphysema Fig 2. Roentgenogram made 3 days after birth showing a hyperexpanded right lung with a shift of the mediastinum to the left. Data Symptoms Mediastinal shift Cyanosis Tachypnea Right middle lobe syndrome Recurrent pneumonitis Location of disease Right upper lobe Right middle lobe Left upper lobe (apical posterior segment) Left upper lobe Resection" Right upper lobectomy Right middle lobectomy Left upper lobectomy Left upper segmentectomy Associated illness Pectus excavatum Asthma Frequent upper respiratory infections Patent ductus arteriosus Hypoglycemia Polycythemia Pierre Robin syndrome Ambiguous genitalia Cleft palate "Six of the 9 patients underwent resection. No. of Patients Fig 3. Lateral chest roentgenogram showing the hyperexpanded right middle lobe. genograms revealed a shift of the mediastinum to the left due to a hyperexpanded, radiolucent right middle lobe (Figs 2, 3). A right middle lobectomy was performed when the infant was 3 days old, with a satisfactory postoperative course. Postoperative chest roentgenogram showed a return of the mediastinum to the

3 35 Haller et al: Lung Bud Anomalies Fig 4. Hyperexpansion of the left upper lobe as docurnented roentgenographically in a 0-year-old boy. midline. The patient had no futher respiratory symptoms. When she was 5 years old, she underwent ligation of a patent ductus arteriosus. PATIENT 2. A 0-year-old white boy had a history of tachypnea as a newborn. When he was born, there was opacification of the left upper lung demonstrated roentgenographically, and he was treated for pneumonia. The density cleared during the first week of life and was replaced by a hyperinflated left upper lobe thereafter. The respiratory symptoms disappeared. Subsequent sweat chloride studies and immunoglobulin concentrations were normal. A lung scan showed minimal perfusion of the left upper lobe, and bronchogram showed no bronchus supplying the hyperinflated area. The child developed normally except for occasional dyspnea on exertion, but by the time he was 0 years old, increasing dyspnea on exercise began to limit his physical activity. Evaluation at this time revealed increased overinflation of the abnormal area (thought to be the apicoposterior segment of the left upper lobe) and progressive shift of the mediastinum to the opposite side. A small, round, parahilar, radiopaque mass was thought to be an obstructed bronchus filled with mucus (Fig 4). Resection of the apical posterior segment was performed. The bronchus to Fig 5. Chest roentgenogram of a 0-iurck-old girl showing hyperinflation of the left lung and a shift of the mediastinurn to the right. this segment was not in communication with the left upper lobe bronchus. The child had an uneventful recovery and was doing well one year after operation. Bronchogenic Cyst We saw 4 patients with bronchogenic cyst. Two were seen in respiratory distress, in the newborn period and at 3 months old. PATIENT 3. A 0-week-old female infant with increasing respiratory distress was transferred by plane from an Iranian hospital. When she was 4 weeks old, she began having respiratory difficulty with episodes of tachypnea and cyanosis. Roentgenograms of the chest showed hyperinflation of the left lung, a shift of the mediastinum to the right, and patchy atelectasis of the right upper and middle lobes (Fig 5). The patient was administered antibiotics and steroids for 6 weeks, but the respiratory difficulty increased. When the patient was seen at our institution, tachypnea to eighty breaths per minute and markedly diminished breath sounds with hyperresonance over the left hemithorax were noted. Barium swallow revealed extrinsic compression of the left main stem bronchus by an oval, radiolucent mass. Bronchoscopy confirmed an anteroposterior narrowing of the left main stem bronchus. At

4 36 The Annals of Thoracic Surgery Vol 28 No July 979 Fig 6. Bronchogram showing inferior displacement of the left bronchial tree by a radiolucent mass of the left upper lobe in a 6-month-old girl. Fig 7. Roentgenogram made shortly after birth showing a left lung field mass and a shift of the mediastinurn to the right. the time of thoracotomy, a bronchogenic cyst was found embedded in the wall of the left main stem bronchus and was removed. The ipsilateral hyperinflation and contralateral atelectasis gradually resolved during the next three months. The patient had an uneventful postoperative course. PATIENT 4. A 6-month-old white female infant was seen with fever and cough. Chest roentgenograms revealed a large mass in the left upper chest with an infiltrate in the peripheral pulmonary tissue suggestive of obstructive pneumonitis. A bronchogram showed the left bronchial tree to be displaced inferiorly by a radiolucent mass in the left upper lobe (Fig 6). A left upper lobectomy was performed, and a 4 by 5 cm cystic mass, lined with ciliated respiratory epithelium, was removed. The patient was asymptomatic on follow-up at 2 months of age; chest roentgenogram was normal. Cystic Adenomatoid Malformations Our series includes 2 patients with cystic adenomatoid malformation. PATIENT 5. A white male infant weighing 3,500 gm was delivered vaginally after a pregnancy complicated by polyhydramnios. The Apgar score was eight at one minute and nine at five minutes. A short time later, respiratory distress developed, and a chest roentgenogram revealed a mass with a "bubbly" appearance in the left lung field, and a mild shift of the mediastinum to the right (Fig 7). Partial pressure of arterial oxygen was initially 58 mm Hg on room air. Respiratory distress increased with progressive shifting of the mediastinum. Urgent operative intervention was recommended. A left lower lobectomy was performed; the specimen was typical of congenital adenomatoid malformation. The postoperative course was complicated only by physiological hyperbilirubinemia, which resolved. Postoperative chest roentgenograms showed a return of the mediastinum to the midline. A 5-month-old black female in- PATIENT 6. fant was evaluated for recurrent left upper lobe pneumonia. A progressive shift of the mediastinum to the right was noted on sequential chest roentgenograms, and a multicystic mass in the left lung field was discovered. An angiogram revealed no systemic vascular supply to the area but marked anterior displacement of the left main pulmonary artery. A left lower lobectomy was performed. The postoperative course was satisfactory. On follow-up three years later, the child was asymptomatic. Mild hyperinflation of the remaining upper lobe was demonstrated on chest roentgenogram.

5 37 Haller et al: Lung Bud Anomalies Table 2. Data on 4 Patients with lntralobar Pulmonary Sequestration Seen at the Johns Hopkins Hospital, 960 to mid-978 Age at Onset of Age at Patient No. Clinical Treat- Treatment of Associated and Sex Symptoms ment Symptoms Sequestration Conditions Follow-up CARDIOVASCULAR PROBLEMS. F Birth 6 mo Uncertain Right lower lobec-... Mild congestive 2. F Birth Cardiac failure; frequent None... pneumonia; failure to thrive 3. F 5 Y' 5 yr Growth retardation; easy Right lower lobec- Congenital subfatigability; pulm. ar- tomy valvular memtery pressure, 38/3 mm Hg brane aortic stenosis tomy 4. M 2 wk 0 wk Cardiac failure; cardiac Left lower lobecoutput 2.5 times normal tomy 5. M 7 Y'... Miminal symptoms; car- Awaiting operation... diac output 2 times normal 6. M 5 d 8 mo Fatigability; asthma; Right lower lobec-... bronchitis; cardiac output.2 times normal; heart enlarged 7. F 6d 6 wk Congestive heart failure Right lower lobec- Patent ductus tomy arteriosus tomy heart failure, no resp. symptoms... Mild congestive heart failure; no resp. symptoms; pulm. artery pressure normal Died mo postop. of acute tracheobronchitis Asymptomatic; heart size normal PULMONARY PROBLEMS 8. F 3 Y' 3 yr Pneumonitis Left lower lobec-... Mild asthma tomy 9. F 3 Y' 6 yr Frequent pneumonitis; Right lower lobec-... Asymptomatic chronic lung abscess tomy 0. F 7 Y' 9 yr Recurrent pneumonitis Right lower lobectomy Systemic lupus erythematosus Asymptomatic. F 6 Y' 7 yr Pneumonitis; empyema Left lower lobectomy... Asymptomatic 2. M 9 mo 2 yr Severe asthma; bronchitis Right lower lobec-... Mild asthma 3. F 6 mo 8 mo Severe asthma; bronchitis tomy Left lower lobe Eventration of Mild asthma segmentectomy left diaphragm 4. F 6d 6 mo Recurrent pneumonia Apical posterior... Doing well segmental resection, right upper lobe Intralobar Pulmonary Sequestration Table 2 summarizes the data on our 4 patients with intralobar pulmonary sequestration. PATIENT 7. A 6-week-old white female infant was seen in congestive heart failure when she was 6 days old. Chest roentgenogram revealed a mass lesion at the right cardiophrenic angle. A continuous heart murmur was noted. Cardiac catheterization and arteriography revealed a large systemic artery arising from the aorta below the diaphragm and entering a cystic right lower lobe mass (Fig 8). Contrast medium drained into the right inferior pulmo- nary vein. Approximately 50% of the cardiac output went through the huge left-to-right shunt. After the cardiac failure had been controlled with digitalis and diuretics, a right lower lobectomy was carried out. The systemic artery was 6 mm in diameter and was long and tortuous. The patient had an uneventful postoperative recovery, with disappearance of the murmur and pulmonary symptoms. PATIENT 2. A 2-year-old white boy was seen with a history of chronic "asthma," recurrent pneumonia, and otitis media. The pneumonic process had always been in the

6 38 The Annals of Thoracic Surgery Vol 28 No July 979 Fig 8. Aortogram showing subdiaphragmatic artery (arrows) supplying the sequestration of the right lower lobe of the lung. right lower lobe. Arteriography revealed a large systemic artery originating near the celiac axis which supplied a right lower lobe sequestration. Right lower lobectomy was performed, and the child had a satisfactory recovery. Four years later chest roentgenogram was normal; the mild asthma required no medication. Comment The initial evidence of the developing respiratory system in a human embryo is a longitudinal groove in the floor of the foregut just caudal to the pharyngeal pouches. In the fourth week of gestation, this laryngotracheal groove appears as a ridge. The caudal part of this ridge gives rise to the epithelium of the lower respiratory system. Soon thereafter, two enlargements develop at the distal end. These are the bronchial or lung buds. As the embryo continues to develop, separation of the trachea and the esophagus occurs and caudal migration transports the lung buds into the thorax. Mesenchymal cells of the splanchnopleure surround the buds and give rise to the tracheal and bronchial walls. During the fifth week, secondary bronchi develop and the adjacent mesenchyma surrounds them and differentiates into the parenchyma of each lobe. Tertiary bronchi appear in the seventh week. By the twenty-fourth to the twenty-eighth week, the epithelium of the terminal air sacs becomes modified into type I alveolar cells and type I cells, which produce the surfactant. Further differentiation transforms the tissues from a glandular structure to a highly vascular, alveolarlike organ which is essentially mature by the end of the twenty-eighth week. Abnormalities in this developmental process can take numerous forms. More and more evidence suggests that lobar emphysema frequently results from anomalous development of a lobar or segmental bronchus. Severe hypoplasia and atresia of a bronchus can be associated with collateral ventilation of the affected lobe, which is easily inflated during inspiration but becomes emphysematous because of air trapping during expiration. In other instances, maldevelopment of bronchial cartilage permits collapse of the wall with a ball-valve effect, which produces progressive emphysema. This anomaly probably occurs during the fourth to sixth week of embryonic development, but the physiological effect may not be clinically apparent for weeks or months after birth depending on the severity of the abnormality. Bronchogenic cysts might properly be called lung bud cysts since they probably originate from embryonic lung bud tissue before the bronchi are formed. For this reason, lung bud cysts can occasionally occur within the wall of a bronchus. They may be lined with squamous epithelium rather than respiratory epithelium. Some have been called esophageal cysts, but embryologically they represent ectopic foregut cells that become displaced before final differentiation takes place. Since they originate before formation of the bronchi, it is not surprising that few if any bronchogenic cysts communicate with normal bronchial lumina. Adenomatoid malformations probably result from cessation of bronchial maturation and concomitant overgrowth of mesenchymal elements, which produces the adenomatoid appearance of the anomaly. Histologically, cartilage is absent, reflecting the bronchial maldevelopment. Often, small bronchial communications exist without cartilaginous support, and

7 39 Haller et al: Lung Bud Anomalies this leads to infection and overinflation of the cystic spaces. A sequestration probably occurs very early in embryonic development before the pulmonary and aortic circulations become separate. Since the venous drainage of intralobar sequestration is into the pulmonary vein, this form of anomaly is less ectopic than extralobar sequestration in which the venous drainage is into the azygos system. Therefore, sequestration could represent a separate mini lung bud, which keeps a systemic artery and drains into either venous system depending on its intimacy with the normal lung bud to which it is adjacent. When these four lung bud anomalies are viewed as abnormalities in early lung development, they become a distinct family of related malformations with sometimes similar but often very different clinical manifestations. To our knowledge, Buntain and associates [2] were among the first to recognize this close relationship. The clinical signs, symptoms, and operative management of the malformation are now reviewed. Congenital Lobar Emphysema Congenital lobar emphysema is an abnormality characterized by massive air trapping in the pulmonary parenchyma. The involved area of the lung is hyperresonant to percussion and has diminished breath sounds, thus mimicking a pneumothorax. The lung becomes overdistended. Ipsilateral compression of adjacent lung occurs along with mediastinal shift to the contralateral side and secondary decrease in venous return to the heart. Together, these factors cause respiratory distress and hypoxemia. In an extensive review of 3 patients by Hendren and McKee [8], the left upper lobe was involved in 46 patients, the right upper lobe in 24, and the right middle lobe in 38. Lower lobe involvement was found in only 2 children. An additional 3 children had bilateral involvement. The onset of symptoms occurred during the first month of life in nearly a third of the patients and by 6 months of age all were symptomatic. Murray [3] stated that congenital lobar emphysema occurs twice as often in male patients as in female patients. The condition can cause life-threatening respiratory distress; in 20 of 66 patients, the complications were rapidly fatal. During the newborn period, the symptom is nearly always respiratory distress; but after the first month of life, pulmonary infection is the most common symptom when the patient is first seen. Hendren [8], Pierce [7], Jones [9], and their associates reported an association of lobar emphysema with congenital heart lesions. Jones and associates [9] noted that 8 of 4 children with lobar emphysema had concomitant congenital heart disease; all were treated by lobectomy. Four children had ventricular septal defects, 2 had tetralogy of Fallot, and 2 had a patent ductus arteriosus. Careful study of the bronchi revealed no overt obstructive lesions in any of the 4 resected specimens. In each infant with congenital heart disease and lobar emphysema, the abnormalities must be assessed as a combined cardiopulmonary defect and the exact physiology of the respiratory distress must be carefully evaluated. Chest roentgenograms are usually definitive in clarifying the differential diagnosis. Bronchoscopy and bronchograms are rarely helpful and instead can be detrimental by increasing respiratory obstruction due to endoscopic trauma. Ventilationiperfusion lung scans show obstructed and delayed ventilation and slightly decreased perfusion of the affected lung. Two of our patients had associated cardiac anomalies:, a ventricular septal defect and, a patent ductus arteriosus. The ductus arteriosus required operative closure at a subsequent date. Leape and Longino [2] suggested that congenital lobar emphysema can be initiated by viscid secretions and perpetuated by bronchial kinking. They suggested that the rarity of confirmatory findings in pathological specimens reflects the difficulty in demonstrating this phenomenon at operation. Fischer and coworkers 6 subsequently suggested that irreversible tissue changes are produced by mucous obstruction. In 967, Murray and associates [4 reported on a patient with mucous plug obstruction, which was relieved by bronchotomy and plug removal. In Murray s [3] review of lobar emphysema, bronchomalacia was identified in 2 patients. Other causes of lobar emphysema which he

8 40 The Annals of Thoracic Surgery Vol 28 No July 979 identified include obstruction by abnormal vessels (in particular, the ductus arteriosus, aneurysmal veins, and aberrant arteries), kinking of the bronchioles, compression by large lymph nodes, intrinsic bronchial obstruction by cartilaginous deficiency, bronchial stenosis, and redundant bronchial mucosa. Bronchial cartilage dysplasia was apparent in only 25% of patients, and in more than 50% of the patients, there was no demonstrable cause. Technical difficulties in measuring the amount of bronchial cartilage present can contribute to the surprisingly low incidence of identifying a specific causative factor. DeMuth and Sloan [4] reported finding residual disease in adjacent lung after removing the most obvious lesions. They observed that, even when resection was performed during infancy, regeneration of lung tissue did not seem to occur. The vital capacity in 5 children operated on during infancy was reduced in comparison to the amount of lung tissue removed. The compensatory pattern was described as one of overdistention, with increased residual volume and decreased vital capacity. Recent studies by Eigen and co-workers [5] and Shannon [9 indicate that lobar emphysema can be a manifestation of generalized lung disease. It appears from their data that there is a loss of elastic recoil of the lung with subsequent airway collapse at abnormally high volumes. The upper lobes are thought to be more involved because they are more passive during respiration. Keith [lo], quoting the study by Eigen and colleagues [5] involving the long-term follow-up of surgically and nonsurgically treated children with congenital lobar emphysema, emphasized that both groups had normal physical growth and were free from pulmonary symptoms. In the lobectomy patients, the vital capacity and total lung capacity were decreased in proportion to the amount of lung tissue resected. Roentgenograms of conservatively treated patients suggest that the distended portions of the lung had not tended to enlarge. In view of these data, Keith [lo] urged consideration of nonsurgical management of patients. However, the last paragraph of the article he cited [5 states: We suggest that conservative treatment is indicated for eupneic, or mildly affected patients regardless of age because both the averred threat to life and the prospect of improved pulmonary function are more than offset by the risk of lobectomy. Neonates who are in severe respiratory distress need immediate excision of the diseased lobe to allow expansion of the less functional but normal lung tissue. Korngold and Baker [ll] in 954 reported on 2 infants cured by aspiration of the involved lobe. Murray [3] noted that 38 of 66 patients required lobectomy. In 2 children, it was necessary after four years of conservative therapy. Mortality was 5O0/o or 4 of the 28 remaining patients who were not operated on. Only 4 of the 4 surviving patients were considered improved or cured. Of the remaining 0, 9 had persistent emphysema and, recurrent pulmonary infection. Leape and Longino [2] reported on 3 patients seen with symptoms during the first month of life. Three treated nonoperatively died. The 9 patients treated by lobectomy were alive and well when the report was published. The treatment of choice appears to be resection, usually lobectomy. The risk of operation is minimal, nowhere near 50%. Most infants are free from symptoms following lobectomy, although l of our patients had episodic wheezing, as did patients of DeMuth and Sloan [4] and Hendren and McKee [8. The latter reported postoperative respiratory abnormalities in 4 of 7 patients. In discussing bronchial atresia as a causative factor of congenital lobar emphysema, Schuster and co-workers [8] made the following remarks: Atresia of the bronchus was first recognized in the adult, but now has been seen on a number of occasions in the newborn and in the young child. It usually affects one or two segments of a lobe and is more common on the left side. Although the bronchus lacks any airway communication centrally, it branches normally distally, and the alveolar size and number is normal at birth. The affected segment or lobe is ventilated through the collateral ventilation and can be seen as a fluid-filled region in the neonate, or as an emphysematous area in the older child. The distorted, cystic bronchus just distal to the atresia is characteristically filled with a mucous plug and presents a recognizable picture radiographically.

9 4 Haller et al: Lung Bud Anomalies Our Patient 2 illustrates this pathophysiology (see Fig 4). Bronchogenic Cysts Congenital cysts of the lung are recognized by their presence in the perinatal period and their characteristic lining of ciliated, columnar epithelium. Bronchogenic cysts represent approximately 0% of mediastinal masses in children. The symptoms are usually related to secondary pulmonary infection, but in the newborn period airway obstruction can be an indication of a cyst. Most cysts are found in the posterior part of the mediastinum at the level of the carina. The right side is affected more often than the left and the lesion is more common in boys than in girls. Opsahl and Berman [6] emphasized that the most common symptoms of bronchogenic cyst are periodic episodes of progressive dyspnea, wheezing, stridor, and cyanosis. They are aggravated by crying or feeding and relieved by oxygen. The episodes usually start early in life and can be accompanied by recurring attacks of pneumonia. Physical findings are those of tachypnea, stridor, rales, and wheezes, with hyperresonance over the affected lung field and occasionally mediastinal shift to the opposite side. Barium swallow should be b ne to demonstrate displacement of the esophagus. Not until 948 was a bronchogenic cyst removed successfully from an infant. Opsahl and Berman 6 reported that only 4 of 25 symptomatic patients had a demonstrable cyst by roentgenographic examination. The cyst was removed successfully in 2 patients. Of the symptomatic patients with normal chest roentgenograms and nonoperative treatment, all died. Cystic Adenomatoid Malformations Congenital cystic adenomatoid malformation was described by Chin and Tang [3] in 949. This abnormality is usually symptomatic in infancy with signs of respiratory distress: tachypnea, subcostal retraction, and cyanosis. It can be indicated by chronic pulmonary infection in older children. The association of adenomatoid malformation with fetal anasarca and maternal polyhydramnios has been reported also. These latter findings are generally limited to stillborn infants. As the malformation undergoes progressive emphysematous enlargement, the mediastinum can be shifted. However, if there is no free communication with the tracheobronchial system, a more indolent, infectious course may result. The abnormal lung tissue consists of an enlarged, meaty, multicystic lobe with smoothwalled cysts of varying sizes, which can communicate with major bronchi through malformed air passages that lack cartilage. The tumor mass appears to have abnormal overgrowth of bronchial tissue with suppression of the alveolar development. Based on electron microscopic studies, Olson and Mendelsohn 5 made the noteworthy observation that the air spaces in this anomaly are lined with persistent type I pneumocytes. These findings establish adenomatoid malformation as a developmental anomaly of the lung bud that occurs at a time preceding the differentiation of cartilage. Proliferation of the bronchial glandular elements is the histological feature giving the name adenomatoid to this abnormality. The characteristic roentgenographic finding is an intrapulmonary mass of soft tissue density containing scattered radiolucent areas of varying size and shape. Usually the mediastinum is displaced away from the mass. In the early perinatal period, a water-density mass may be apparent before the cysts become air-filled. This is probably fetal pulmonary fluid trapped in the spaces. If the lower lobe is involved, the abnormality can closely mimic diaphragmatic hernia and can only be differentiated by a barium swallow. Taber and Schwartz [20 described the overall appearance as a "Swiss cheese wedge." Because mediastinal shift causes notable compression of normal pulmonary tissue, reported patients with cystic adenomatoid malformation either required operation or were examined postmortem. Experience has shown that procedures less than lobectomy are not successful [ll. Abnormal pulmonary vessels to the malformation have been reported in 2 of 29 resections for cystic adenomatoid malformation.

10 42 The Annals of Thoracic Surgery Vol 28 No July 979 Intralobar Pulmonary Sequestration Intralobar pulmonary sequestration results from either an aberrant pulmonary tissue developing within the normal lung or an anomalous lung bud fusing with the normally developing, primordial pulmonary tissue. The unique characteristic of this abnormality is its systemic arterial supply, usually a separate artery arising from the descending thoracic or abdominal aorta. Not infrequently, this artery arises below the diaphragm and courses cephalad to the aberrant pulmonary tissue. lntrapulmonary sequestration is much more common than its developmental counterpart, extralobar sequestration; the latter is aberrant pulmonary tissue that is extrinsic to the normal lung and is invested with a separate pleural covering. Its exact derivation is unclear and because of its rarity, it is excluded from our discussion of sequestration in this group of patients. The symptoms of intralobar pulmonary sequestration in older children and young adults are respiratory in origin. The complications are usually secondary to chronic recurring pneumonia with fluid-filled intrapulmonary cysts, many of which are associated with purulent bronchiectasis and abscess formation. However, as noted by White and associates [2], intralobar pulmonary sequestration can have an acute neonatal presentation associated with congestive heart failure and pulmonary edema secondary to a large shunt from the aorta through the aberrant artery into the pulmonary venous system. Patient 7 is an example of a child with acute respiratory distress in the newborn period secondary to pulmonary congestion, while Patient 2 is illustrative of a child with the more common presentation of chronic recurring pulmonary infection with a clinical syndrome of relapsing pneumonia in a localized segment of the lung. Intralobar sequestration need not have a bronchial communication with the normal tracheobronchial tree, and, therefore, infection can be late in occurring, possibly on the basis of bloodborne infection rather than tracheobronchial contamination. In some cases there is a clearly recognizable anatomical communication between the sequestered segment and the normal tracheobronchial tree. Operative management of this condition is predicated on either relief of the congestive heart failure by division of the systemic arterial supply with concomitant removal of the sequestered pulmonary tissue or control of infection by removal of the destroyed bronchiectatic segment. In the course of operative management, the systemic artery must be carefully identified and divided. The technical error of overlooking the systemic arterial supply can lead to catastrophic hemorrhage, especially in patients with chronic inflammatory disease. In our series, a lobectomy was usually necessary for removal of the intralobar sequestration although occasionally a segmental resection was sufficient. In summary, these clearly related lung bud anomalies can be seen with acute symptoms in the neonatal period, either as a result of intrathoracic pressure mechanics or congestive heart failure; or they can be recognized in older children as radiopaque areas within normal pulmonary tissue associated with symptoms and signs of pulmonary infection and bronchiectasis. Less severe tension problems can be associated with milder forms of these anomalies in which partial obstruction of secondary bronchi can be present. While none of these anomalies contains neoplastic tissue or tissue that could become malignant, the cardiovascular and pulmonary manifestations require early, definitive diagnosis and therapy. In the newborn group, life-saving emergency operation can be necessary. References. Breckenridge RL, Gibson ET: Congenital cystic adenomatoid malformation of the lung. J Pediatr 67:863, Buntain WL, Isaacs H Jr, Payne VC, et al: Lobar emphysema, cystic adenomatoid malformation, pulmonary sequestration and bronchogenic cyst in infancy and childhood: a clinical group. J Pediatr Surg 9:85, Chin KY, Tang MY: Congenital adenomatoid malformation of one lobe of a lung with general anasarca. Arch Pathol48:22, DeMuth GR, Sloan H: Congenital lobar em-

11 43 Haller et al: Lung Bud Anomalies physema: long-term effects and sequelae in treated cases. Surgery 59:60, Eigen H, Lemen RJ, Waring WW: Congenital lobar emphysema: long-term evaluation of surgically and conservatively treated children. Am Rev Respir Dis 3:823, Fischer HW, Lucidio JL, Lynxwiler CP: Lobar emphysema. JAMA 66:340, Haller JA Jr, Shermeta DW, Donahoo JS, et al: Life-threatening respiratory distress from mediastinal masses in infants. Ann Thorac Surg 9:364, Hendren HW, McKee D: Lobar emphysema of infancy. J Pediatr Surg :24, Jones JC, Almond CH, Snyder HM, et al: Lobar emphysema and congenital heart disease in infancy. J Thorac Cardiovasc Surg 49:, Keith HH: Congenital lobar emphysema. Pediatr Ann 6:34, 977. Korngold HW, Baker JM: Non-surgical treatment of unilobar obstructive emphysema of the newborn. Pediatrics 4:296, Leape LL, Longino LA: Infantile lobar emphysema. Pediatrics 34:246, Murray GF: Congenital lobar emphysema (collective review). Surg Gynecol Obstet 24:6, Murray GF, Talbert JL, Haller JA Jr: Obstructive lobar emphysema of the newborn infant. J Thorac Cardiovasc Surg 53:886, Olson JL, Mendelsohn G: Congenital cystic adenomatoid malformation of the lung. Arch Pathol Lab Med 02:248, Opsahl T, Berman EJ: Bronchogenic mediastinal cysts in infants: case report and review of the literature. Pediatrics 30:372, Pierce WS, DeParedes CG, Friedman S, et al: Concomitant congenital heart disease and lobar emphysema in infants. Ann Surg 72:95, Schuster SR, Kirkpatrick JA, Harris BGC, et al: Bronchial atresia: a recognizable entity in the pediatric age group. J Pediatr Surg (in press) 9. Shannon DC: The natural history of lobar "emphysema." Am Rev Respir Dis 3:42, Taber P, Schwartz DW: Cystic lung lesion in a newborn: congenital cystic adenomatoid malformation of the lung. J Pediatr Surg 7:366, White JJ, Donahoo JS, Ostrow IT, et al: Cardiovascular and respiratory manifestations of pulmonary sequestration in childhood. Ann Thorac Surg 8:286, 974