Actualización y controversias en el tratamiento de las malformaciones congénitas de la vía aérea pulmonar / Update and disagreements in the treatment of congenital pulmonary airway malformations

Congenital pulmonary airway malformations (CPAM) are rare and occur due to a failure in lung embryological development. They are classified according to their pathological characteristics and their anatomical origin. They can occur from the antenatal period to adulthood, can be associated with hydrops fetalis, respiratory distress, recurrent infections, or in an otherwise asymptomatic patient. In this article we carry out a scope review of the literature to answer frequent questions of the clinical teams in charge of patients with CPAM, such as the antenatal approach, the different types of surgeries and the management of asymptomatic patients. Although the indication for surgery is clear in symptomatic patients, little is known about its natural history of this condition, including the possibility of spontaneous resolution and the development of complications or neoplasm. So, the treatment of asymptomatic patients continues to be controversial. Therapeutic decisions must be made by multidisciplinary teams with the informed participation of parents and patients. In our opinion, considering the excellent results of minimally invasive surgery, its low incidence of complications, and practically zero mortality when performed by experienced groups, it seems reasonable to consider elective resection of a MCVAP in asymptomatic patients.

Las malformaciones congénitas de la vía aérea pulmonar (MCVAP) son infrecuentes y ocurren debido a una falla en el desarrollo embriológico pulmonar. Se clasifican de acuerdo con sus características patológicas y a su origen anatómico. Se pueden presentar desde el periodo antenatal hasta la adultez, asociarse a cuadros de hidrops fetal, distrés respiratorio, infecciones recurrentes, o como un hallazgo en pacientes asintomáticos. En este artículo realizamos una revisión bibliográfica exploratoria para responder dudas frecuentes de los equipos clínicos a cargo de pacientes con MCVAP, como el enfrentamiento antenatal, los distintos tipos de cirugía y su abordaje, y el manejo de pacientes asintomáticos. Si bien la indicación de cirugía es clara en pacientes sintomáticos, poco se conoce acerca de su historia natural, incluyendo la posibilidad de resolverse de forma espontánea, de complicarse o de evolucionar hacia el desarrollo de una neoplasia, por lo que el tratamiento de pacientes asintomáticos continúa siendo controversial. Las decisiones terapéuticas deben ser tomadas por equipos multidisciplinarios con la participación informada de los padres y de los pacientes. En nuestra opinión, considerando los excelentes resultados de la cirugía mínimamente invasiva, su baja incidencia de complicaciones y prácticamente nula mortalidad, al ser realizada por grupos con experiencia, nos parece razonable plantear la resección electiva de una MCVAP en un paciente asintomático.

Fetal lung transcriptome patterns in an ex vivo compression model of diaphragmatic hernia.

BACKGROUND: The purpose of this study was to employ a novel ex vivo lung model of congenital diaphragmatic hernia (CDH) to determine how a mechanical compression affects early pulmonary development. METHODS: Day-15 whole fetal rat lungs (n = 6-12/group) from nitrofen-exposed and normal (vehicle only) dams were explanted and cultured ex vivo in compression microdevices (0.2 or 0.4 kPa) for 16 h to mimic physiologic compression forces that occur in CDH in vivo. Lungs were evaluated with significance set at P < 0.05. RESULTS: Nitrofen-exposed lungs were hypoplastic and expressed lower levels of surfactant protein C at baseline. Although compression alone did not alter the α-smooth muscle actin (ACTA2) expression in normal lungs, nitrofen-exposed lungs had significantly increased ACTA2 transcripts (0.2 kPa: 2.04 ± 0.15; 0.4 kPa: 2.22 ± 0.11; both P < 0.001). Nitrofen-exposed lungs also showed further reductions in surfactant protein C expression at 0.2 and 0.4 kPa (0.53 ± 0.04, P < 0.01; 0.69 ± 0.23, P < 0.001; respectively). Whereas normal lungs exposed to 0.2 and 0.4 kPa showed significant increases in periostin (POSTN), a mechanical stress-response molecule (1.79 ± 0.10 and 2.12 ± 0.39, respectively; both P < 0.001), nitrofen-exposed lungs had a significant decrease in POSTN expression (0.4 kPa: 0.67 ± 0.15, P < 0.001), which was confirmed by immunohistochemistry. CONCLUSIONS: Collectively, these pilot data in a model of CDH lung hypoplasia suggest a primary aberration in response to mechanical stress within the nitrofen lung, characterized by an upregulation of ACTA2 and a downregulation in SPFTC and POSTN. This ex vivo compression system may serve as a novel research platform to better understand the mechanobiology and complex regulation of matricellular dynamics during CDH fetal lung development.

Midface and upper airway dysgenesis in FGFR2-related craniosynostosis involves multiple tissue-specific and cell cycle effects.

Midface dysgenesis is a feature of more than 200 genetic conditions in which upper airway anomalies frequently cause respiratory distress, but its etiology is poorly understood. Mouse models of Apert and Crouzon craniosynostosis syndromes exhibit midface dysgenesis similar to the human conditions. They carry activating mutations of Fgfr2, which is expressed in multiple craniofacial tissues during development. Magnetic resonance microscopy of three mouse models of Apert and Crouzon syndromes revealed decreased nasal passage volume in all models at birth. Histological analysis suggested overgrowth of the nasal cartilage in the two Apert syndrome mouse models. We used tissue-specific gene expression and transcriptome analysis to further dissect the structural, cellular and molecular alterations underlying midface and upper airway dysgenesis in Apert Fgfr2+/S252W mutants. Cartilage thickened progressively during embryogenesis because of increased chondrocyte proliferation in the presence of Fgf2 Oral epithelium expression of mutant Fgfr2, which resulted in a distinctive nasal septal fusion defect, and premature facial suture fusion contributed to the overall dysmorphology. Midface dysgenesis in Fgfr2-related craniosynostosis is a complex phenotype arising from the combined effects of aberrant signaling in multiple craniofacial tissues.

Association Between Tetralogy of Fallot and Tracheobronchial Branching Abnormalities: A New Clue for Pathogenesis?

BACKGROUND: In our practice, we noticed an increased frequency of tracheobronchial branching abnormalities (TBAs) in patients with tetralogy of Fallot (ToF). This study aimed to determine whether an association exists between congenital TBAs and ToF with or without pulmonary atresia. METHODS AND RESULTS: The frequency of TBAs on chest computed tomography was assessed in 55 patients with ToF without pulmonary atresia, 34 patients with ToF with pulmonary arteria, and 100 control patients. We then looked for a possible association between TBAs and pulmonary artery branch hypoplasia, the presence of major aortopulmonary collateral arteries, and the presence of the chromosome 22q11 deletion. TBAs were significantly more frequent in patients with ToF with or without pulmonary atresia than in the control group (any TBAs, 21% versus 2% [P<0.001]; bronchial situs anomalies, 6% versus 0% [P=0.002]; right tracheal bronchus, 4% versus 0% [P=0.04]; left eparterial bronchus, 8% versus 0% [P=0.005]); and tended to be more frequent in those with ToF without pulmonary atresia than in those with ToF with pulmonary atresia (any TBAs, 27% versus 12% [P=0.11]; left eparterial bronchus, 13% versus 0% [P=0.04]). TBAs were readily multiple (8 patients of 19 with TBA) and concerned essentially the upper lobes. TBAs were not associated with pulmonary branch hypoplasia, major aortopulmonary collateral arteries, or the chromosome 22q11 deletion. CONCLUSIONS: We demonstrated a significantly increased frequency of tracheobronchial abnormalities in patients with ToF with or without pulmonary atresia compared with a control group. These results suggest an interaction between abnormalities in conotruncal septation and tracheobronchial branching and may provide a new clue to the pathogenesis of conotruncal heart diseases.

Outcome of prenatally diagnosed congenital lung anomalies in the North of England: a review of 228 cases to aid in prenatal counselling.

OBJECTIVE: To describe data on congenital lung anomalies identified on prenatal ultrasound from two centres in the North of England. METHOD: This retrospective case series includes all cases notified to the Northern Congenital Abnormality Survey from 1990 to 2010 and to Leeds Regional Fetal Medicine Unit 2000-2015. RESULTS: There were a total of 228 cases, 101 from Northern Congenital Abnormality Survey and 127 from Leeds Regional Fetal Medicine Unit. Eight-five per cent were unilateral congenital pulmonary airway malformations (CPAMs), 2% bilateral CPAMs and 11% bronchopulmonary sequestrations. Mediastinal shift was present in 50% of cases, occurring more frequently in macrocystic CPAMs and larger lesions. Polyhydramnios was evident in 28%, and fetal hydrops occurred in 9%. Prenatal regression occurred in 54%, and lesions were no longer visible on ultrasound in 27% at a later gestation. Prenatal intervention was performed in 5% of cases, and postnatal surgical intervention was required in 12% due to ongoing respiratory symptoms. Regression of fetal hydrops occurred in five cases. CONCLUSION: The outcome was favourable in 83% cases. Prenatal regression was common, and macrocystic lesions were less likely to regress than microcystic lesions. No specific prenatal features predicted the need for early surgical intervention. The data analysed in this prenatal series will help when counselling prenatal cases. © 2017 John Wiley & Sons, Ltd.

Rare Upper Airway Anomalies.

A broad spectrum of congenital upper airway anomalies can occur as a result of errors during embryologic development. In this review, we will describe the clinical presentation, diagnosis, and management strategies for a few select, rare congenital malformations of this system. The diagnostic tools used in workup of these disorders range from prenatal tests to radiological imaging, swallowing evaluations, indirect or direct laryngoscopy, and rigid bronchoscopy. While these congenital defects can occur in isolation, they are often associated with disorders of other organ systems or may present as part of a syndrome. Therefore workup and treatment planning for patients with these disorders often involves a team of multiple specialists, including paediatricians, otolaryngologists, pulmonologists, speech pathologists, gastroenterologists, and geneticists.

Prenatal diagnosis of esophageal bronchus--first report of a rare foregut malformation in utero.

AIM OF THE STUDY: Esophageal bronchus is a rare bronchopulmonary foregut malformation in which an isolated portion of the respiratory system communicates with the esophagus. There are no reports of prenatal diagnosis of an esophageal bronchus in the literature. We present 5 cases of esophageal bronchus and describe unique imaging findings. METHODS: Following IRB approval, 5 cases of pathologically proven esophageal bronchus were identified from a single center fetal therapy surgical database. Prenatal magnetic resonance and ultrasound studies were scored for the presence of bronchoceles, cysts, vascular feeders, and location. Five control cases were selected from a radiology database, with lesions determined to represent bronchial atresia prenatally and located at the lung bases. All imaging was reviewed blinded to outcome. MAIN RESULTS: A tubular T2 hyperintense structure (bronchocele) directed from the lung lesion to the gastroesophageal junction was seen in all cases of esophageal bronchus, but in none of the control cases. In all control cases, the bronchocele was directed to the pulmonary hilum. The presence of cysts or vascular feeding vessels was not statistically significant in identifying an esophageal bronchus lesion. All patients were delivered at term and underwent surgical resection between 5 to 19 weeks of age. No postoperative complications occurred. CONCLUSION: Prenatal diagnosis of an esophageal bronchus can be strongly suggested by the presence of a T2 hyperintense structure arising from a lung lesion and directed towards the GE junction. These findings may be helpful for better counseling of parents and improved surgical planning.

A complete corticotropin releasing factor system localized in human fetal lung.

OBJECTIVE: The Corticotropin Releasing Factor (CRF) system (neuropeptides CRF, Ucn I, II, III and binding sites CRFR1, CRFR2, CRF-BP) is responsible for stress regulation and the homeostasis of an organism. Herein we study the CRF system in human normal and pathological fetal lungs. DESIGN: Lung tissues from 46 archival human fetuses were divided into Group A (normal), Group B (chromosomal abnormalities) and Group C (congenital disorders). Presence of elements of the CRF system was evaluated using immunohistochemistry and was correlated to pathology, lung developmental stage and clinicopathological characteristics. RESULTS: Immunoreactivity for all antigens was found in both epithelial and mesenchymal lung cells of the bronchi and alveoli. Ucn I and CRFR1 were more frequently present in Group A. Ucns were more frequently localized at the pseudoglandular stage. There was a positive correlation between the presence of the CRF neuropeptides and between CRFR1 and CRF. Two fetuses with lung malformations showed low or no detectable presence of the CRF system. CONCLUSIONS: We report the presence of a complete CRF system in human fetal lungs correlating its developmental stage and several pathologies. Our results are in agreement with findings in experimental animal models, implicating the CRF system in fetal lung development, its action being more significant in the early stages.

Bronquio traqueal / Tracheal bronchio

Tracheal bronchus is considered an anatomical variant or bronchial malformation. Its clinical manifestations are rare, and are due to a failure to drain bronchial secretions. Anatomically it may be a supernumerary or ectopic bronchus. His diagnosis is made by direct visualization of images and airway. Generally its treatment is expectant.

El bronquio traqueal es considerado como una variante anatómica o malformación bronquial. Sus manifestaciones clínicas son infrecuentes, y se deben a una falla para el adecuado drenaje de secreciones bronquiales. Anatómicamente puede tratarse de un bronquio supernumerario o ectópico. Su diagnóstico se realiza mediante imágenes y visualización directa de la vía aérea. En general su tratamiento es expectante.

Embryology of the early foregut.

In embryology, no agreement exists how the early foregut differentiates into the respiratory tract and the intestinal tract. In particular, the formation of the early lung anlage as well as the process of separation of trachea and esophagus remains unclear. This process is explained in a rather schematic way and aims more to explain pathologic findings, whereas true embryologic investigations are extremely rare in this field. Here, scanning electron microscopy of the normal foregut development illustrates the steps, which finally leads to the development of larynx and trachea on the one hand, and pharynx and esophagus on the other hand. This study was performed in chicken embryos in accordance to the developmental stages described. As the main results from these illustrations show, we found no evidence for lateral foregut ridges inside the undivided foregut chamber and no fusion of lateral foregut components to form a trachea-esophageal septum.

Laryngeal cleft.

Laryngeal clefts are rare congenital anomalies, first described in 1792 by Richter, that allow communication between the tracheal and esophageal axis. The incidence is 1 in 10,000 to 20,000 births, which represents approximately 1.5% of the laryngeal pathology in children. Laryngeal clefts result from a failure of fusion of the posterior cricoid lamina and development of the tracheoesophageal septum. Recent work has further refined our understanding of this complex development.

Exploiting mechanical stimuli to rescue growth of the hypoplastic lung.

Impaired lung development afflicts a range of newborns cared for by paediatric surgeons. As a result the speciality has led in the development of surgical models that illustrate the biomechanical regulation of lung growth. Using transgenic mutants, biologists have similarly discovered much about the biochemical regulation of prenatal lung growth. Airway smooth muscle (ASM) and its prenatal contractility airway peristalsis (AP) represent a novel link between these areas: ASM progenitors produce an essential biochemical factor for lung morphogenesis, whilst calcium-driven biomechanical ASM activity appears to regulate the same. In this invited paper, I take the opportunity both to review our recent findings on lung growth and prenatal ASM, and also to discuss mechanisms by which ASM contractility can regulate growth. Finally, I will introduce some novel ideas for exploration: ASM contractility could help to schedule parturition (pulmonary parturition clock) and could even be a generic model for smooth muscle regulation of morphogenesis in similar organs.

Lung development and implications for hypoplasia found in congenital diaphragmatic hernia.

Congenital diaphragmatic hernia (CDH) is associated with various degrees of pulmonary hypoplasia and severe persistent pulmonary hypertension in the newborn. These conditions have significant implications for the outcome for the patient. Defects in early lung development are likely to be central to the generation of hypoplasia. A number of mouse models with defects in pathways that are central to lung development were found to have CDH. Understanding all aspects of early lung development will provide fresh insight into the pathogenesis of CDH and its associated conditions.

Peristalsis of airway smooth muscle is developmentally regulated and uncoupled from hypoplastic lung growth.

Prenatal airway smooth muscle (ASM) peristalsis appears coupled to lung growth. Moreover, ASM progenitors produce fibroblast growth factor-10 (FGF-10) for lung morphogenesis. Congenital diaphragmatic hernia (CDH) is associated with lung hypoplasia, FGF-10 deficiency, and postnatal ASM dysfunction. We hypothesized ASM dysfunction emerges in tandem with, and may contribute toward, the primordial lung hypoplasia that precedes experimental CDH. Spatial origin and frequency of ASM peristaltic waves were measured in normal and hypoplastic rat lungs cultured from day 13.5 of gestation (lung hypoplasia was generated by nitrofen dosing of pregnant dams). Longitudinal lung growth was assayed by bud counts and tracing photomicrographs of cultures. Coupling of lung growth and peristalsis was tested by stimulation studies using serum, FGF-10, or nicotine and inhibition studies with nifedipine or U0126 (MEK1/2 inhibitor). In normal lung, ASM peristalsis is developmentally regulated: proximal ASM becomes quiescent (while retaining capacity for cholinergic-stimulated peristalsis). However, in hypoplastic lung, spontaneous proximal ASM activity persists. FGF-10 corrects this aberrant ASM activity in tandem with improved growth. Stimulation and inhibition studies showed that, unlike normal lung, changes in growth or peristalsis are not consistently accompanied by parallel modulation of the other. ASM peristalsis undergoes FGF-10-regulated spatiotemporal development coupled to lung growth: this process is disrupted early in lung hypoplasia. ASM dysfunction emerges in tandem with and may therefore contribute toward lung hypoplasia in CDH.

Recent advances in sonographic imaging of fetal thoracic structures.

Recent ultrasonographic methods applied in the evaluation of fetal thoracic structures and anomalies are presented. Fetal lung volumetric assessment by 3D ultrasonography, analysis of the thoracic wall by 3D-rendered image and 3D skeletal-mode imaging, intrathoracic vessel evaluation by 3D power Doppler ultrasonography, analysis of heart anatomy and abnormalities by 4D spatiotemporal image correlation, identification of normal and abnormal intrathoracic almost isoechogenic structures by volume contrast imaging and evaluation of the heart and great vessels by 3 and 4D inverse mode will be reviewed.

Prenatal diagnosis and management of mainstem bronchial atresia.

The prenatal diagnosis, natural history and management of mainstem bronchial atresia have not been described previously. We report two cases of prenatally diagnosed proximal bronchial atresia. The first patient presented at 18 weeks with sonographic and MRI findings consistent with bronchial atresia with fetal hydrops. The mother developed the mirror syndrome and labor was induced. A non-viable fetus was delivered at 25 weeks. The second patient presented at 16 weeks gestation with evidence of an intrathoracic mass that was subsequently prenatally diagnosed as a right mainstem bronchial atresia. The right lung increased rapidly in size and was associated with the onset of fetal hydrops. At 24 weeks, fetal pneumonectomy was performed but the fetus expired intraoperatively due to cardiovascular collapse. Post-mortem findings in both cases confirmed the presence of an atretic mainstem bronchus with massive enlargement of the lung. Bronchial atresia involving the mainstem bronchus is associated with a poor prognosis.

Bronchopulmonary foregut malformations: embryology, radiology and quandary.

Bronchopulmonary foregut malformations (BPFM) are a heterogeneous group of pulmonary developmental anomalies that present at varying ages and with overlapping symptoms, signs and radiology. This article discusses the embryology of these lesions with reference to possible common origins and the link between aetiology and radiological appearance. The radiology of each lesion, both antenatally and postnatally, is described and illustrated. A number of quandaries exist in the prediction of prognosis and subsequent treatment of BPFM. We discuss the radiological features that may help to elucidate an individual prognosis and aid in the planning of treatment. The treatment options available for BPFM are briefly discussed. Finally, the link between BPFM, in particular cystic adenomatoid malformations and malignancy, is discussed. We aim to provide a comprehensive overview of the embryology, radiology, prognosis and treatment highlighting contentious issues of BPFM.

Association between pulmonary hypoplasia and hypoplasia of arcuate nucleus in stillbirth.

OBJECTIVE: To investigate lung development and to correlate pulmonary hypoplasia with hypoplasia of the arcuate nucleus in stillbirths. STUDY DESIGN: We examined 26 stillbirths which occurred after 25 complete gestational weeks. The brainstem and the lung were the particular focus of this study. The brainstem was examined according to the protocol routinely followed in our Institute. As regards the lung examination, the development stage was evaluated on the basis of the correlation between lung and body weight (LW/BW), and according to microscopic parameters, that is, the presence of cartilaginous bronchi up to the distal level and the radial alveolar count (RAC). The normal reference values for the last 3 months of gestation correspond to >0.022 for LW/BW and from 2.2 to 4.4 for RAC. RESULTS: In 17 cases (65%) pulmonary hypoplasia was observed, characterized by a LW/BW value below 0.022 and RAC below 2.2. In nine cases (35%), microscopic examination of brainstem serial sections showed varying degrees of hypoplasia of the arcuate nucleus (ARCn). In eight cases (31%) the pulmonary hypoplasia was associated with hypoplasia/agenesis of the ARCn. CONCLUSIONS: This study demonstrated that in about a third of stillbirths there is a congenital hypodevelopment of both lung and arcuate nucleus. In these cases the ARCn hypoplasia would exert a negative effect on respiratory movements in utero and therefore on lung development. When the pulmonary hypoplasia is not accompanied by hypodevelopment of this nucleus the explanation could be a failure to block the inhibitory action of the Kölliker-Fuse nucleus.