Pulmonary underdevelopment is a rare congenital disease which manifests as persistent hemithorax opacification at chest radiography. We present three patients with different types of pulmonary underdevelopment, their imaging features and associated anomalies. Case 1 is a premature neonate with persistent respiratory distress. Further imaging confirmed right pulmonary hypoplasia, associated with a patent foramen ovale, patent ductus arteriosus and vertebral anomalies. Case 2 is a 6-year-old child with corrected anorectal malformation, and recurrent pneumonia. Further imaging confirmed left pulmonary aplasia, associated with an aberrant right subclavian artery and vertebral anomaly. Case 3 is a full term neonate who developed excessive drooling of saliva and respiratory distress. Further imaging confirmed right pulmonary agenesis, associated with an atrial septal defect, patent ductus arteriosus and tracheo-oesophageal fistula. Pulmonary underdevelopment is classified into three types: hypoplasia, aplasia and agenesis. The majority of them have associated anomalies. This condition should be considered a differential diagnosis in paediatric patients with an opaque hemithorax on chest radiography.
Pulmonary underdevelopment is a spectrum of rare malformations, consisting of agenesis, aplasia and hypoplasia.
A premature baby boy, born at 28 weeks via breech assisted delivery, was the first twin of a monochorionic diamniotic pair. He was born non-vigorous with poor breathing and weak muscle tone. Intubation was necessary post-delivery because of oxygen desaturation. He was initially treated for respiratory distress syndrome and later complicated with pseudomonas aeruginosa septicaemia.
Serial chest radiographs (CXR) showed persistent right homogeneous opacity. Echocardiography demonstrated a patent foramen ovale (PFO), a large patent ductus arteriosus (PDA) and mild tricuspid regurgitation. Computed tomography angiography (CTA) of the thorax (
Computed tomography angiography thorax (A) demonstrates hypoplastic right lung, right lower lobe bronchi (RLB), right pulmonary artery (RPA) and veins (RPV). The right hemithorax volume is reduced with ipsilateral mediastinal shift. Large patent ductus arteriosus (PDA) connecting with the aorta (AO). Posterior CT imaging (B) demonstrates left hemivertebrae at C7/T1 and T8/T9, butterfly vertebrae of T5 and T7, and left C7/T1 cervical rib.
A 6-year-old girl underwent an anorectal malformation correction at another hospital when she was very young. She also presented with recurrent episodes of pneumonia. In view of persistent homogeneous opacification of the left hemithorax on CXR, she underwent CT thorax at 4 months of age which revealed a congenital anomaly of the left lung.
She was referred to our hospital with gradually increasing exertional dyspnoea, which restricted her physical activities. CTA thorax (
Coronal Computed tomography angiography thorax demonstrates absence of the left lung and pulmonary vessels. The LMB shows abrupt termination after the carina (thick black arrow). The mediastinum is completely displaced to the left side. There is associated fusion of the C2–C3 vertebrae (thin white arrow).
A full term baby boy was born with good Apgar scores. Antenatal ultrasound had revealed polyhydramnios. Several hours after delivery, the baby developed excessive drooling of saliva and increasing respiratory distress, requiring intubation. The right breath sounds were absent with limited advancement of the feeding tube. CXR revealed complete opacity of the right hemithorax, ipsilateral mediastinal shift, contralateral lung hyperinflation and looping of the feeding tube at mid upper thoracic level. Echocardiography demonstrated dextrocardia, an atrial septal defect (ASD) and a PDA. CTA thorax (
Computed tomography angiography thorax in the axial (A) and oblique coronal (B) planes reveals absence of the right lung, bronchus and pulmonary vessels with ipsilateral mediastinal shift. The left pulmonary artery (LPA) and veins (LPV) are present with a hyperinflated left lung. The trachea (T) divides into the left main bronchus (LMB) and communicates with the lower oesophagus (Oe) via a fistula (F) consistent with a tracheo-oesophageal fistula. The patent ductus arteriosus (PDA) is large. The tip of the central venous catheter (CVC) is in the right atrium (RA).
The lower oesophagus communicated directly with the carina in keeping with a tracheo-oesophageal fistula. The main pulmonary artery was 1.5 times larger than the ascending aorta suggestive of pulmonary hypertension (
Both cases 1 and 3 succumbed at very young ages. Case 1 had recurrent oxygen desaturation episodes and passed away at 32 weeks of age. Case 3 died 1 week post-surgery because of a nosocomial lung infection and deteriorated cardiac function.
Case 2 was discharged home with a salbutamol metered-dose inhaler (MDI) as required. She had occasional rapid breathing and wheezing during strenuous physical activities, and also when experiencing an upper respiratory tract infection. The symptoms resolved with the salbutamol MDI. She displayed failure to thrive despite having a good appetite.
Pulmonary underdevelopment is classified into three groups.
It is suggested that pulmonary agenesis and aplasia may be considered as one entity clinically and developmentally.
Pulmonary agenesis is generally sporadic, with only a few reported cases of autosomal recessive inheritance. It has no gender predilection, and it affects both lungs equally.
On the other hand, pulmonary hypoplasia can be thought as either primary or secondary. Primary pulmonary hypoplasia is less common, and it is when the cause cannot be identified.
The aetiologies of unilateral thorax opacification vary according to age. The five most common aetiologies are large pleural effusion, obstruction of the main bronchus, pneumonia, intrathoracic tumours and pulmonary underdevelopment. In neonates, congenital diaphragmatic hernia, congenital large hyperlucent lobe and congenital thoracic malformation should also be considered as the differential diagnoses.
The position of the mediastinum provides important clues to the underlying conditions. Contralateral mediastinal shift is seen in space occupying entities like intrathoracic tumours and large pleural effusion.
In patients with reduced or absent breath sounds, a decrease or absence of movement of the unilateral chest wall and an opaque hemithorax on chest radiograph, the diagnosis of pulmonary agenesis should be considered.
The prognosis of pulmonary underdevelopment is largely dependent upon the remaining functional lung parenchyma, as well as the presence and severity of the associated abnormalities.
Pulmonary underdevelopment has a wide range of clinical presentations and can occur at any age. The severity of the disease ranges from hypoplasia to agenesis, and there may be variable degrees of associated anomalies. Even though it is rare, it should be considered as one of the differential diagnoses, especially in patients with an opaque unilateral hemithorax on plain film radiography. An early diagnosis is important for early initiation of the treatment, thereby preventing possible complications.
The authors would like to thank Ooi Kieam Lim and Noor Syarida Ayu Mohamed Sukeri for their expertise in acquiring the radiological images.
The authors declare that they have no financial or personal relationships that may have inappropriately influenced them in writing this article.
T.A.R.M. prepared the whole manuscript including designing and drafting. K.A.S. was the author who interpreted the radiological images, suggested the overall concepts, proofread and edited the manuscript. C.N. was the supervisor for the case report. M.R.M.Z. provided the case and contributed to the clinical discussion.
This article followed all ethical standards for research. The cases were all anonymised. Verbal consent for inclusion in the publication was obtained from the carers.
This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
Data sharing is not applicable to this article, as no new data were created or analysed in this study.
The views and opinions expressed in this article are those of the authors and do not necessarily reflect the official policy or position of any affiliated agency of the authors.