Multicystic Lobar Lung Lesion in a Preterm Neonate

A female infant aged 24 weeks and 5 days gestation is born to a G3P1 mother aged 30 years old via cesarean section for breech presentation in the setting of preterm labor. The mother receives a course of antenatal steroids. Pregnancy is complicated by type 2 diabetes mellitus. The infant’s birth weight is 581 g (22.5 percentile for weight on the Fenton growth chart), with proportional head circumference and length. The infant is intubated at delivery, receives surfactant, and stabilizes on first intention high-frequency oscillatory ventilation as per the center’s protocol. The initial chest radiograph at birth is consistent with respiratory distress syndrome. Due to the increasing fraction of inspired oxygen (FiO2) requirement to a maximum of 0.85, a second dose of surfactant is given on the day of life 4. She is transitioned to a high-frequency jet ventilator (HFJV) and receives a third dose of surfactant on the day of life 9, given poor oxygenation on FiO2 of 1. Her oxygenation remains challenging, and a chest radiograph demonstrates optimal endotracheal tube position, multiple cystic lucencies in the right lower lobe with focal hyperinflation, and associated mass effect with right upper lung collapse and mediastinal shift. An 18-day course of intravenous dexamethasone is started on day 12 of life as the FiO2 requirement remains high. She later develops a large, well-demarcated lucency in the anterior midline chest representing pneumomediastinum, so HFJV settings are adjusted. The 4 sigh breaths were removed, and the positive end-expiratory pressure decreased from 14 to 12 cm H2O, with subsequent resolution of pneumomediastinum by the next day. Her oxygenation remains suboptimal with worsening cystic changes with emphysematous blebs in her right lung (Figure 1A). The infant continued to be managed on HFJV over the next several days. Many interventions are attempted, including antibiotic treatment of possible pneumonia, repositioning, sedation, and paralysis, without sustained improvement. A trial of left mainstem intubation (Figure 1B) is pursued for a few hours, which she did not tolerate with ensuing severe hypercarbia and needing a FiO2 of 1, prompting retraction of the endotracheal tube from the left main stem bronchus. As the infant’s clinical condition is not improving on different ventilator strategies, including a trial of single-lung ventilation, general surgery is consulted for possible lobectomy. She is transferred to the level IV neonatal intensive care unit (NICU) on the day of life 36.The differential diagnosis of cystic lung lesions in this premature infant includes severe cystic pulmonary interstitial emphysema (PIE) secondary to ventilator-associated lung injury, cystic pulmonary airway malformation (CPAM), and congenital lobar emphysema (CLE). Other differential diagnoses in an infant presenting with cystic lung disease include necrotizing pneumonia, pneumatocele, congenital diaphragmatic hernia, and cystic bronchopulmonary dysplasia.After transferring to the level IV NICU for surgical evaluation, the patient becomes critically ill and hypotensive, likely due to mediastinal compression by the significant cystic changes in the right lung. After aggressive fluid resuscitation and inotropic support, a computed tomography (CT) of the chest with contrast is obtained, revealing a large right lower lobe multicystic lesion, which the radiologist reports to be consistent with a type I CPAM (Figure 2). The following day, at 30 weeks and 1 day postmenstrual age (PMA) and weighing 1300 g, she underwent a right lower lobe lobectomy with a preoperative diagnosis of type 1 CPAM. A surgical specimen is sent for pathology review. The patient rapidly improves postoperatively, and ventilator settings are weaned as tolerated. She receives a 10-day course of dexamethasone to aid with extubation. She is successfully extubated (Figure 3), weaned progressively to room air by 36 weeks PMA, and discharged home at 39 weeks PMA on room air, taking all oral feeds.The patient is now 62 weeks PMA, thriving well, and is healthy without any respiratory issues.Histopathology confirmed the diagnosis of cystic PIE (Figure 4).PIE is a ventilator-associated acquired disease of preterm neonates caused by air leakage into the interstitial space and characterized by radiolucency along the perivascular sheaths. PIE causes ventilation/perfusion mismatch and compression of unaffected lung tissue and can lead to pneumothorax, pneumomediastinum, and/or pneumopericardium.1,2Managing PIE can be complex, as increased support from mechanical ventilation may worsen the cystic lesions, which may compress the unaffected adjacent lung tissue, impairing oxygenation and ventilation. Thus, it may be necessary to tolerate hypercapnia while attempting to wean the mean airway pressure to prevent worsened distension. Positioning the affected side of the chest down and using high-frequency jet ventilation help decrease further distension and worsening of PIE. For the subset of patients whose cysts worsen and coalesce, there may be a role for single-lung ventilation, as described by Rastogi et al.3 In term infants, a trial of selective bronchial blockade can be attempted to determine if single-lung ventilation can be tolerated before subjecting the infant to lobectomy.4 In refractory cases, there are reports of surgical intervention with lobectomy.5,6 Histopathology provides a definitive diagnosis of the PIE, and resection may be curative in the most severe cases.Based on this experience, we only had a definitive diagnosis after resection. To our knowledge, there is no literature in pediatric surgery regarding the optimal timing for surgical intervention in cystic lung lesions in premature infants. In the future, we recommend considering early surgical consultation and CT imaging to better delineate the extent of lung involvement. If severe diffuse cystic PIE involves a single lobe of the lung and is not responding to medical management, surgical resection of the affected lobe can be curative.While rare, refractory PIE may present as a worsening cystic lung disease that progresses to the point of hemodynamic instability.High-frequency ventilation and patient positioning are the first lines of management for PIE.In refractory cases of PIE, surgical consultation may be warranted for potential lobectomy.American Board of Pediatrics Neonatal-Perinatal Content SpecificationRecognize the clinical, laboratory, and imaging features of air leaks.Know how to prevent and manage air leaks.Know the appropriate management for an infant with congenital malformations of the lung, including congenital pulmonary lymphangiectasia, and cystic lung diseases, such as CLE, cystic adenomatoid malformation, and mediastinal tumors.