Publications
Recurrent, Persistent Pneumothorax in a Neonate A Cryptic Cause
Hegde, Shalini G.; Mohanty, Suravi1; Balachander, Bharathi; Shubha, A. M. Abstract
Newborns, especially preterms, have a higher risk of developing pneumothorax. We report a 33-week preemie who presented with recurrent, persistent right pneumothorax, which failed to resolve with standard treatment. The child underwent surgical removal of a suspect nonexpanding upper lobe of the right lung with clinical improvement. Histopathology was atypical but nearly consistent with congenital pulmonary airway malformation (CPAM). This report highlights the clinicopathological discordance noted and aims to draw an embryological explanation toward the atypical histomorphology of CPAM in preemies. INTRODUCTION
Both invasive and noninvasive ventilation of a sick neonate predisposes to pneumothorax. Mortality among ventilated newborns with pneumothorax is twice as high and accounts for 12.8%.[1] We report here a preterm neonate with persistent pneumothorax due to an unusual cause, its surgical management, and outcome with a probable explanation of the embryological maldevelopment. CASE REPORT
A 1.6 kg male, 33-week preemie, delivered by cesarean section due to maternal preeclampsia, had respiratory distress since birth requiring continuous positive airway pressure. Antenatal anomaly scans were normal. The child received surfactant, but by 8 h of life, he had to be mechanically ventilated for worsening distress. Chest X-ray revealed right-sided pneumothorax for which an intercostal tube drainage (ICTD) was inserted. His respiratory parameters improved, and ventilatory support was withdrawn in 2 days. Following transient stabilization, pneumothorax recurred, necessitating re-ventilation, chest tube reinsertion, and drainage with two tubes. Contrast-enhanced computed tomography chest showed residual pneumothorax with two ICTDs in situ and apparently normal lungs [Figure 1]. Failed response to conservative treatment prompted for a right thoracotomy on day 16 of life. A nonexpanding right upper lobe which failed to inflate even with positive pressure rendered by the anesthetist was removed [Figure 2]. The child thereafter had an uneventful recovery. The cut surface of the lobe showed multiple ill-defined gray-white areas with no cysts. Histopathology, however, was consistent with bronchopulmonary malformation-congenital pulmonary airway malformation (CPAM). The baby is now a year old and well. DISCUSSION
Incidence of pneumothorax in neonates admitted to intensive care units is 1%–2%, but with mechanical ventilation and coexisting lung pathology, it can be as high as 30%.[2] The concurrent pulmonary conditions that predispose to pneumothorax are respiratory distress syndrome, meconium aspiration syndrome, neonatal asphyxia, transient tachypnea of newborn, hyaline membrane disease, pneumonia, diaphragmatic eventration, and congenital lung and thoracic malformations.[3] Treatment includes tube thoracostomy with noninvasive or invasive ventilatory support in all, except in the mild ones. When associated with a compromised pulmonary physiology, pneumothorax has an overall mortality of 15%–20%.[4] Preterm neonates are especially vulnerable and have a higher incidence of pneumothorax ranging from 3.8% to 9%,[5] along with a higher rate of recurrence of 28% as against 10% in term babies and a mortality of 38.6%.[6] Low birth weight, male gender, and rupture of membranes longer than 24 h increase the risk.
Our patient developed pneumothorax within 48 h of life and had risk factors of prematurity, male gender, respiratory distress syndrome, surfactant use, and mechanical ventilation. However, the persistence of pneumothorax in spite of appropriate treatment was unusual. Persistent pneumothorax is defined as pneumothorax lasting for more than 7 days. In the index child, change of intercostal tubes, change of track, and insertion of two tubes along with mechanical ventilation were the strategies employed, and yet except for transient improvement, pneumothorax recurred.
There are isolated reports of neonatal persistent pneumothorax treated with povidone-iodine,[7] fibrin glue injection,[8] selective bronchial occlusion/intubation, and autologous blood patch pleurodesis.[9] We have limited experience with these, especially in premature neonates, and hence opted for a surgical exploration.
All bronchopulmonary malformations predispose to pneumothorax but have salient radiological features such as microcysts or macrocysts in CPAM, hyperinflated herniating lobe in congenital lobar emphysema, and segmental opacity in sequestration. None were noted in any of the chest radiographs of the child. Akin to the radiological discordance, histopathology of the lobe too was atypical. Figure 3a shows mildly dilated bronchiole-like spaces separated by normal alveoli suggestive of a CPAM. These spaces were closely spaced but did not show classical back-to-back arrangement. The gross appearance of the resected lung also had no cysts. There were few areas resembling sequestration [Figure 3b] with uniformly dilated bronchioles, alveolar ducts, and alveoli with mild chronic inflammation in the parenchyma. However, morphologically, the upper lobe was affected; there was normal bronchopulmonary communication and no separate blood supply from the aorta, unlike a sequestrated lobe.
(a) Microscopy showing mildly dilated bronchiole-like spaces separated by normal alveoli suggestive of congenital pulmonary airway malformation. spaces are closely spaced but do not show back-to-back arrangement (H and E, ×10). (b) Areas resembling sequestration with uniformly dilated bronchioles, alveolar ducts, and alveoli with mild chronic inflammation in the parenchyma and congested blood vessels (H and E, ×10). Inset highlights mild chronic inflammation and congested blood vessels in the lung parenchyma
CPAM, congenital lobar emphysema, sequestration, and bronchogenic cyst are the four types of bronchopulmonary malformations. CPAM, in particular, has a cystic overgrowth of terminal bronchioles. Both imaging and histopathology in our child did not concur with any specific type of the above. The treatment of any bronchopulmonary malformations involves excision of the affected segment/lobe, which presents as multiple small air-filled cysts on the X-ray. Although the embryological insult resulting in disorganized growth occurs at around the 35th day of life, the lesion changes morphologically in parallel with the normal development of the lung. The lung development is divided into five stages – embryonic (3–7 weeks), pseudoglandular (7–17 weeks), canalicular (17–26 weeks), saccular (26–36 weeks), and alveolar (36 weeks to birth).[10] The discordance observed here can be explained by the hypothesis that since the child was a 33-week preemie, the CPAM did not progress through its usual course of formation of cysts and was probably arrested in the saccular phase of lung development.
