Phenotypic and genetic spectrum of alveolar capillary dysplasia: a retrospective cohort study

Alveolar capillary dysplasia with misalignment of the pulmonary veins: A surgical lung biopsy and autopsy in a full-term newborn

Alveolar capillary dysplasia with misalignment of the pulmonary veins (ACD/MPV) is a rare and lethal interstitial lung disorder, caused by a congenital abnormality affecting the development of the parenchyma and pulmonary vessels. We report the case of a newborn at the end of 40 weeks of pregnancy, who showed no cardiopulmonary anomalies in prenatal control ultrasounds. However, after delivery, pulmonary hypertension and hypoxemic respiratory failure became apparent. She died after 12 days from refractory hemodynamic and respiratory failure despite intensive therapy. A surgical lung biopsy and clinical autopsy were performed, both revealing the same histopathological signs consistent with this disorder. In our case, the findings of digestive and genital malformations, together with the genetic result of the alteration in the FOXF1 gene, led us to conclude the definitive diagnosis of alveolar capillary dysplasia.

Pulmonary Hypertension in Developmental Lung Diseases

Diverse genetic developmental lung diseases can present in the neonatal period with hypoxemic respiratory failure, often associated with with pulmonary hypertension. Intractable hypoxemia and lack of sustained response to medical management should increase the suspicion of a developmental lung disorder. Genetic diagnosis and lung biopsy are helpful in establishing the diagnosis. Early diagnosis can result in optimizing management and redirecting care if needed. This article reviews normal lung development, various developmental lung disorders that can result from genetic abnormalities at each stage of lung development, their clinical presentation, management, prognosis, and differential diagnoses.

Lung biopsies in infants and children in critical care situation

INTRODUCTION

Lung biopsy is considered as the last step investigation for diagnosing lung diseases; however, its indication must be carefully balanced with its invasiveness. The present study aims to evaluate the diagnostic yield of lung biopsy in critically ill patients hospitalized in the pediatric intensive care unit (ICU).

MATERIAL AND METHODS

Children who underwent a lung biopsy in the ICU between 1995 and 2022 were included. Biopsies performed in the operating room and post-mortem biopsies were excluded.

RESULTS

Thirty-one patients were included, with a median age of 18 days (2 days to 10.8 years); 21 (67.7%) were newborns. All patients required invasive mechanical ventilation, 26 (89.7%) had a pulmonary hypertension, and 22 (70.9%) were placed under extracorporeal membrane oxygenation (ECMO). The lung biopsy led to a diagnosis in 81% of the patients. The diagnostic reliability seemed to decrease with age (95% in newborns, 71% in 1 month to 2 years and 0/3 patients aged over 2 years old). Diffuse developmental disorders of the lung accounted for 15 (49%) patients, primarily alveolar capillary dysplasia, followed by surfactant disorders in 5 (16%) patients. Complications occurred in 9/31 (29%) patients including eight under ECMO, with massive hemorrhages in seven cases.

DISCUSSION AND CONCLUSION

In critical situations, lung biopsy should be performed. Lung biopsy is a reliable diagnostic procedure for neonates in critical situation when a diffuse developmental disorder of the lung is suspected. The majority of lung biopsy complication was associated with the use of ECMO. The prospective evaluation of the complications of such procedure under ECMO, and particularly over 10 days of ECMO and in children over 2-year-old remains to be ascertained.

Twins with alveolar capillary dysplasia with misalignment of pulmonary veins: Strategies for diagnosis and management

We present a case of dichorionic-diamniotic twin females who developed hypoxemic respiratory failure. They were ultimately diagnosed by lung biopsy with alveolar capillary dysplasia with misalignment of pulmonary veins. This case highlights a practical approach to reaching a diagnosis in infants with suspected developmental lung disease.

Rapid genome diagnosis of alveolar capillary dysplasia leading to treatment in a child with respiratory and cardiac failure

Alveolar capillary dysplasia (ACD) is a fatal disorder that typically presents in the neonatal period with refractory hypoxemia and pulmonary hypertension. Lung biopsy is traditionally required to establish the diagnosis. We report a 22-mo-old male who presented with anemia, severe pulmonary hypertension, and right heart failure. He had a complicated hospital course resulting in cardiac arrest and requirement for extracorporeal membrane oxygenation. Computed tomography of the chest showed a heterogenous pattern of interlobular septal thickening and pulmonary edema. The etiology of his condition was unknown, lung biopsy was contraindicated because of his medical fragility, and discussions were held to move to palliative care. Rapid whole-genome sequencing (rWGS) was performed. In 2 d it resulted, revealing a novel FOXF1 gene pathogenic variant that led to the presumptive diagnosis of atypical ACD. Cases of atypical ACD have been reported with survival in patients using medical therapy or lung transplantation. Based on the rWGS diagnosis and more favorable potential of atypical ACD, aggressive medical treatment was pursued. The patient was discharged home after 67 d in the hospital; he is currently doing well more than 30 mo after his initial presentation with only one subsequent hospitalization and no requirement for lung transplantation. Our case reveals the potential for use of rWGS in a critically ill child in which the diagnosis is unknown. rWGS and other advanced genetic tests can guide clinical management and expand our understanding of atypical ACD and other conditions.

Optical genome mapping for prenatal diagnosis: A prospective study

PURPOSE

Cytogenetic analysis provides important information for prenatal decision-making and genetic counseling. Optical genome mapping (OGM) has demonstrated its performances in retrospective studies. In our prospective study, we assessed the quality of DNA obtained from cultures of amniotic fluid (AF) and chorionic villi (CV) and evaluated the ability of OGM to detect all clinically relevant aberrations identified by standard methods.

METHODS

A total of 37 prenatal samples from pregnancies with a fetal anomaly on ultrasound were analyzed prospectively by OGM between January 1, 2021 and June 31, 2022. OGM results were interpreted blindly and compared to the results obtained by standard techniques.

RESULTS

OGM results were interpretable in 92% of samples. We observed 100% concordance between OGM and karyotype and/or chromosomal microarray results. In addition, OGM identified a median of 30 small (<100 kb) structural variations per case with the involvement of 12 OMIM genes, of which 3 were OMIM morbid genes.

CONCLUSION

This prospective study showed OGM performed well in detecting genomic alterations in cell cultures from prenatal samples. The place of OGM in relation to CMA or exome sequencing remains to be defined in order to optimize the prenatal diagnostic procedure.

Extracorporeal Membrane Oxygenation (ECMO) for suspected neonatal genetic diagnoses with cardiorespiratory failure

Recent data describe an increasing use of extracorporeal membrane oxygenation (ECMO) in neonates with various clinical conditions besides primary respiratory or cardiac diagnoses. Infants with underlying genetic disorders characterized by cardiopulmonary failure pose unique management challenges. When pathognomonic dysmorphic features for common genetic diagnoses are not present, the prognosis is uncertain at best when determining ECMO candidacy. Lengthy turnaround times of genetic testing often delay definitive diagnosis during the ECMO course. Clinical management pathways to guide practice and evidence to support the use of ECMO in rare genetic conditions are lacking. The decision to initiate ECMO is daunting but may be of benefit if the subsequent genetic diagnosis is non-lethal. In lethal genetic cases warranting discontinuation of care, the time spent on ECMO may still be advantageous as a bridge to diagnosis while allowing for parental bonding with the terminally ill infant. Diagnostic confirmation may also facilitate the attainment of closure for these parents. Here, we report our experience providing ECMO to three neonates presenting with cardiorespiratory failure and later diagnosed with rare genetic syndromes. We share the challenges faced, lessons learned, and outcomes of these critically ill neonates.

Unusual presentation of alveolar capillary dysplasia with misalignment of the pulmonary veins in a child with respiratory syncytial virus pneumonia: A case report

Alveolar capillary dysplasia with misalignment of the pulmonary veins (ACDMPV) is a rare congenital diffuse lung disorder, with a fatal course during the neonatal period. We describe an 18-month-old boy who presented with respiratory syncytial virus pneumonia and pulmonary hypertensive crisis requiring extracorporeal membrane oxygenation. Exome sequencing revealed a FOXF1 frameshift variant, NM_001451.2:c.995_998delACTC, inherited from his asymptomatic mother. Genetic findings were compatible with histopathology findings from a lung biopsy. Based on the disease course, histopathology, and outcomes of this case, we believe ACDMPV should be considered a possibility in an infant presenting with hypoxemic respiratory failure, resistant pulmonary hypertension, and vasodilator-induced pulmonary edema. Genetic testing can contribute to the diagnostic process.

Pulmonary hypertension in the newborn- etiology and pathogenesis

A disruption in the well-orchestrated fetal-to-neonatal cardiopulmonary transition at birth results in the clinical conundrum of severe hypoxemic respiratory failure associated with elevated pulmonary vascular resistance (PVR), referred to as persistent pulmonary hypertension of the newborn (PPHN). In the past three decades, the advent of surfactant, newer modalities of ventilation, inhaled nitric oxide, other pulmonary vasodilators, and finally extracorporeal membrane oxygenation (ECMO) have made giant strides in improving the outcomes of infants with PPHN. However, death or the need for ECMO occurs in 10-20% of term infants with PPHN. Better understanding of the etiopathogenesis of PPHN can lead to physiology-driven management strategies. This manuscript reviews the fetal circulation, cardiopulmonary transition at birth, etiology, and pathophysiology of PPHN.

Interstitial lung disease in infancy and early childhood: a clinicopathological primer

Children's interstitial lung disease (chILD) encompasses a wide and heterogeneous spectrum of diseases substantially different from that of adults. Established classification systems divide chILD into conditions more prevalent in infancy and other conditions occurring at any age. This categorisation is based on a multidisciplinary approach including clinical, radiological, genetic and histological findings. The diagnostic evaluation may include lung biopsies if other diagnostic approaches failed to identify a precise chILD entity, or if severe or refractory respiratory distress of unknown cause is present. As the majority of children will be evaluated and diagnosed outside of specialist centres, this review summarises relevant clinical, genetic and histological findings of chILD to provide assistance in clinical assessment and rational diagnostics.

ILD of childhood is comparable by name only to lung disease in adults. A dedicated interdisciplinary team is required to achieve the best possible outcome. This review summarises the current clinicopathological criteria and associated genetic alterations.https://bit.ly/3mpxI3b

Two cases of different genetic variants of alveolar capillary dysplasia associated with left-sided obstructive CHDs

Alveolar capillary dysplasia with misalignment of the pulmonary veins is an uncommon disorder that affects the lung vasculature development in the neonatal period and leads to pulmonary hypertension. We describe two patients with alveolar capillary dysplasia associated with left-sided obstructive heart defects with two different genetic variants. Our cases highlight the importance of early recognition of this disease in the setting of persistent and supra-systemic pulmonary hypertension despite surgical correction of the associated lesions. Identification of these cases will facilitate the development of a multidisciplinary approach and provide guidance to the affected families.

Early prenatal diagnosis of alveolar capillary dysplasia with misalignment of pulmonary veins due to a 16q24.1 deletion

First trimester ultrasound screening is an essential fetal examination performed generally at 11-13 weeks of gestation (WG). However, it does not allow for an accurate description of all fetal organs, partly due to their development in progress. Meanwhile, increased nuchal translucency (INT) is a widely used marker known to be associated with chromosomal deleterious rearrangements. We report on a 14 WG fetus with an association of INT and univentricular congenital heart malformation (CHM) leading to chorionic villous sampling (CVS). Cytogenetic investigations performed using array-Comparative Genomic Hybridization (CGH) and fluorescence in situ hybridization (FISH) demonstrated a 1.17 Mb deletion in 16q24.1 encompassing FOXF1 arisen de novo on maternal inherited chromosome. Fetopathological study confirmed CHM with hypoplastic left heart syndrome (HLHS) associating aortic atresia, mitral stenosis, and left ventricular hypoplasia and revealed in addition specific lung lesions corresponding to alveolar capillary dysplasia with misalignment of pulmonary veins (ACDMPV). This is so far the first case of first trimester prenatal diagnosis of ACDMPV due to the deletion of FOXF1 gene. An interpretation of the complex genomic data generated by ultrasound markers is facilitated considerably by the genotype-phenotype correlations on fetopathological examination.

[Interstitial lung disease in infancy and early childhood]

Diffuse interstitial lung disease of infancy (chILD) shows a spectrum of disease substantially different from that of adults. Established classification systems divide chILD into conditions that are more prevalent in infancy and conditions that occur at any age. The classification is based on a multidisciplinary approach including clinical, radiological, genetic, and histological findings. Lung biopsies become necessary if other diagnostic investigations have not identified a precise chILD or if severe or refractory respiratory distress of unknown cause is present. As the majority of pediatric lung biopsies will be received first by pathologists outside of specialist centers this review summarizes relevant clinical and histological findings of chILD.