Alveolar capillary dysplasia with misalignment of the pulmonary veins: a rare but fatal cause of neonatal respiratory failure

Misalignment of lung vessels and alveolar capillary dysplasia: a case report with autopsy

Misalignment of lung vessels (MLV) with or without alveolar capillary dysplasia (ACD) is a rare cause of idiopathic persistent pulmonary hypertension of the neonate. This report describes a full-term infant with severe and intractable pulmonary hypertension. The patient's condition progressively deteriorated despite high-frequency oscillatory ventilation, infusion of magnesium sulfate, dopamine, and dobutamine to control blood pressure, and nitric oxide inhalation therapy. The infant died at 5 days of age. The diagnosis of MLV with ACD was established by autopsy. Histopathologic analysis revealed a failure of formation and an ingrowth of alveolar capillaries, thickening of the alveolar walls, poor contact of capillaries with alveolar epithelium, small intra-acinar muscularized arterioles, and anomalous pulmonary veins within bronchovascular bundles. The low rate of diagnosis of MLV with or without ACD may be because of the early high mortality rate or patchy involvement in some cases. Increasing awareness of this clinical entity may prevent the use of costly, invasive, and probably ineffective procedures. Short-term improvement after inhalation of nitric oxide does not lead to long-term survival but merely provides time for potential lung transplantation.

A novel association of alveolar capillary dysplasia, atypical duodenal atresia, and subglottic stenosis

Alveolar capillary dysplasia (ACD), which is a rare and lethal congenital pulmonary anomaly found in newborns, begins its onset or causes deterioration of the infant's condition some time after birth. Various congenital anomalies in combination with ACD have been reported, except for subglottic stenosis. Therefore, we aim to report a novel association in a case of ACD with the combination of atypical duodenal atresia and subglottic stenosis. The male infant was scheduled for duodeno-duodenostomy because a double-bubble sign was observed on a chest radiograph. He arrived at the operating theater without any symptoms. After induction of general anesthesia, although mask ventilation was performed without difficulties throughout the entire procedure, oxygen saturation values of the upper and lower extremities dissociated after several attempts of intubation. Surgery was canceled because of instability of the respiratory condition. Respiratory insufficiency worsened progressively, and the infant died at 5 days of age. An autopsy confirmed ACD and revealed cartilaginous subglottic stenosis, which had made intubation difficult. This report highlights the hazards of the onset and worsening of ACD, and the importance of thorough echocardiography before surgery when atypical duodenal atresia is suspected. Anesthesiologists should also be prepared for the difficulty of intubation.

Alveolar capillary dysplasia: absence of CD117 immunoreactivity of putative hemangioblast precursor cells

Alveolar capillary dysplasia is a rare cause of irreversible persistent pulmonary hypertension in newborns resulting from failure of formation of peripheral capillary loops with consequent reduction in the blood-gas barrier. The basic defect in morphogenesis is unknown, although it is postulated that there is a structural abnormality of the hemangioblast precursors of the primitive lung mesenchyme in the septal regions of the developing lung leading to abnormal vasculogenesis. Two cases of alveolar capillary dysplasia evaluated immunohistochemically showed uniform CD117 negativity in the septal interstitial cells forming the pulmonary capillaries. A series of 12 control cases showed positive immunoreactivity for CD117 in a subset of septal interstitial cells forming the putative hemangioblast precursor cells. This novel finding is a useful adjunctive diagnostic tool and may support the hypothesis that absence of putative CD117-positive hemangioblast precursor cells is a key structural defect. This defect results in abnormal vasculogenesis and consequent failure of formation of an adequate blood-gas barrier.

Congenital alveolar capillary dysplasia and associated gastrointestinal anomalies

Congenital alveolar capillary dysplasia is a rare cause of irreversible pulmonary hypertension with 100% mortality. We present three cases of congenital alveolar capillary dysplasia with associated gastrointestinal abnormalities. Three full-term neonates presented with pulmonary hypertension needing ventilatory support by oscillation. Of the three, two neonates subsequently needed extracorporeal membrane oxygenation. Abdominal distension associated with bilious aspirates was the gastrointestinal manifestation. One child had duodenal atresia and anorectal anomaly, one with intestinal malrotation and the other with a rare combination of intestinal malrotaion and total colonic Hirschsprung's disease. All three infants succumbed to pulmonary hypertension at mean age 34 days. The etiopathogenesis and pathology of this condition are discussed with a comprehensive review of the literature.

Alveolar capillary dysplasia: a logical approach to a fatal disease

PURPOSE

The aim of the study was to review the authors' experience with alveolar capillary dysplasia (ACD), a cause of persistent pulmonary hypertension of the neonate (PPHN) caused by decreased alveolar units, dilated anomalous pulmonary veins, thick-walled arterioles, and thickened interalveolar septa.

METHODS

The records of all neonates with ACD were reviewed from Children's Hospital, Columbus, Ohio, and Sophia's Children's Hospital, Rotterdam, The Netherlands. The clinical characteristics and pathological findings are discussed.

RESULTS

Eight neonates were diagnosed with ACD from 1994 to 2002. Twenty-five percent (2/8) experienced respiratory distress immediately after birth, whereas 75% (6/8) had normal Apgar scores but deteriorated 1.5 hours to 30 days after birth. All infants required conventional ventilation initially; 50% (4/8) were placed on high-frequency oscillating ventilation and 87% (7/8) on extracorporeal membrane oxygenation. A premorbid diagnosis was established in 3 patients by open lung biopsy. The diagnosis of ACD was confirmed at autopsy in all patients.

CONCLUSIONS

ACD is a fatal disease that should be suspected in all neonates with respiratory failure and PPHN who fail conventional therapy. Prompt diagnosis helps to avoid prolongation of costly treatment modalities in a uniformly fatal disease. An algorithm is proposed in which neonates with PPHN who fail treatment with extracorporeal membrane oxygenation are managed by open lung biopsy.

Pulmonary pathology

Common causes of neonatal respiratory distress include meconium aspiration, pneumonia, persistent pulmonary hypertension of the newborn, pneumothorax and cystic adenomatoid malformation. Genomics and proteomics have enabled the recent recognition of several additional disorders that lead to neonatal death from respiratory disease. These are broadly classified as disorders of lung homeostasis and have pathological features of proteinosis, interstitial pneumonitis or lipidosis. These pathological changes result from inherited disorders of surfactant proteins or granulocyte-macrophage colony stimulating factor. Abnormal lung vascular development is the basis for another cause of fatal neonatal respiratory distress, alveolar capillary dysplasia with or without associated misalignment of veins. Diagnosis of these genetically transmitted disorders is important because of the serious implications for future siblings. There is also a critical need for establishing an archival tissue bank to permit future molecular biological studies.

Dysplasie alvéolo-capillaire avec défaut d’alignement des vaisseaux pulmonaires

Alveolar capillary dysplasia (ACD), with or without pulmonary vein misalignment is a uniformly fatal cause of persistent pulmonary hypertension and respiratory failure, first described in 1981. We report the case of ACD in a full term newborn with post mortem pathologic confirmation. Sixty five cases have been reported in the literature, most are sporadic, but a few cases of familial ACD suggest an autosomal recessive inheritance. In 55% of the reported cases of ACD other cardiovascular, digestive or urogenital anomalies were associated. ACD is presumed to be a primary capillary disorder. It affects full-term neonates who exhibit respiratory distress during the early post natal period due to pulmonary hypertension and die within 3 weeks of birth. Histologic findings include a decrease in the number of alveolar capillaries, which are placed centrally within the intralobular septa, ectatic veins accompany the bronchovascular bundles instead of being in their normal position in the interlobular septum, and muscularized pulmonary arteries extend to the distal level. Prognosis is very poor, intravenous prostacyclin with inhaled nitric oxide have been reported in the cases with the best survival.

Open lung biopsy in neonatal and paediatric patients referred for extracorporeal membrane oxygenation (ECMO)

BACKGROUND

This study was undertaken to determine the usefulness, safety, and most appropriate timing of open lung biopsy in infants and children considered for and on extracorporeal membrane oxygenation (ECMO) for respiratory failure.

METHODS

A retrospective review of children referred for consideration of and placed on ECMO in our institution in the period 1996-2002.

RESULTS

506 patients were referred, 15 (3%) of whom underwent antemortem open lung biopsy (eight neonatal, four paediatric, and three cardiac patients). In the neonatal group open lung biopsy contributed to clinical decision making in all patients. Four neonates had a fatal lung dysplasia (three alveolar capillary dysplasia and one surfactant protein B deficiency) and treatment was withdrawn. Of the other four neonates, two had pulmonary hypoplasia, one had pulmonary lymphangiectasia, and one had meconium aspiration with mild barotrauma. Treatment was continued in these four patients and two survived. In the paediatric group the biopsies were of clinical relevance in two infants with pertussis who had lung infarction on biopsy in whom treatment was withdrawn. In the other two paediatric patients the biopsies were equivocal, treatment was continued, but both patients died. In the cardiac group, who presented perioperatively with pulmonary hypertension, the biopsies excluded a fatal lung dysplasia and severe pulmonary vascular disease but all three infants died. One patient had non-fatal bleeding complications.

CONCLUSION

Open lung biopsy is clinically most useful when performed to diagnose fatal lung dysplasias in neonates and to confirm the presence of viable lung tissue in patients with acute lung injury due to pertussis infection.

Misalignment of lung vessels: diagnostic role of conventional histology and immunohistochemistry

Misalignment of lung vessels represents a rare congenital anomaly that may cause respiratory failure in the newborn. It is characterized by abnormal position of pulmonary veins and venules that lie adjacent to arteries and bronchi, and it is usually associated with a decreased number of alveolar capillaries (i.e., alveolar capillary dysplasia), although these two conditions have been separately described. Awareness of this anomaly is required by pathologists because it can be easily overlooked on lung biopsy or autopsy, and because definite diagnosis relies on histology. We report the case of a newborn male baby who developed respiratory distress 18 h after an uncomplicated delivery. The patient died on the 7th day, after high frequency oscillatory ventilation, nitric oxide inhalation and extracorporeal membrane oxygenation were unsuccessful. On autopsy, histology and immunohistochemistry demonstrated diffuse changes, fulfilling diagnostic criteria of misalignment of lung vessels and of alveolar capillary dysplasia in both lungs, with muscularization of very peripheral pulmonary arteries and a prominent interstitial and periadventitial fibrosis. Diffuse distribution of vessel misalignment could explain the rapid onset of respiratory failure, and the presence of diffuse fibrosis might have contributed to irreversible respiratory dysfunction by impairment of lung parenchyma extensibility.

Incidence of alveolar capillary dysplasia in severe idiopathic persistent pulmonary hypertension of the newborn

OBJECTIVE

To determine the incidence and outcome and to review the management of alveolar capillary dysplasia (ACD) among newborns with severe idiopathic persistent pulmonary hypertension (PPHN).

METHODS

A retrospective review of medical records of infants admitted to a paediatric intensive care unit from 1982 to 2000 with a diagnosis of severe PPHN, and re-examination of lung histological sections was carried out.

RESULTS

Thirteen new-born infants with pulmonary hypertension not associated with any known cause were identified. All were treated with conventional mechanical ventilation or high-frequency oscillatory ventilation with high inspired-oxygen and non-specific pulmonary vasodilators. Nine infants were also treated with inhaled nitric oxide therapy and eight with extracorporeal membrane oxygenation (ECMO). Seven infants died and six survived. At autopsies, the histological features of ACD were seen in the six who had died in the newborn period. All these had been treated with ECMO. In two of these six infants, lung biopsies had been performed showing similar features, suggesting the possibility of diagnosis during life. In the remaining infant, who died at 3 months of age, there was only marked hypertrophy of the muscle coat in the small pulmonary arteries.

CONCLUSIONS

Alveolar capillary dysplasia is probably not as rare a condition as previously suggested in sporadic case reports from literature on the subject. It should be entertained as a cause of otherwise severe idiopathic PPHN of the newborn, particularly if ECMO is required. Diagnosis during life is possible by lung biopsy. It is uncertain if survival occurs with milder forms of the condition.

Congenital alveolar capillary dysplasia with misalignment of pulmonary veins associated with hypoplastic left heart syndrome

Three full-term infants died in the first month of life with hypoplastic left heart syndrome (HLH) and persistent pulmonary hypertension (PPH). At postmortem examination, they were found to have alveolar capillary dysplasia with misalignment of pulmonary veins (ACD with MPV). The association of HLH syndrome, and ACD with MPV with intestinal malrotation and/or obstruction, is unique. Decreased blood flow in the ascending aorta in fetuses with left outflow tract obstruction might cause vasoconstriction of pulmonary arterioles to maintain cerebral perfusion. Vasoconstriction early during embryogenesis might lead to decreased growth and development of alveolar capillaries and pulmonary veins. This results in pulmonary hypertension, and the arterial blood is forced to bypass the deficient capillary bed and can drain only via the anomalous bronchial veins.