|Year : 2016 | Volume
| Issue : 1 | Page : 110-113
Unilateral pulmonary hypoplasia in an adult
Akshay Ajit Shah, Anjali R Singh, Amit T Kharat
Department of Radio-Diagnosis, Dr. D. Y. Patil Medical College, Hospital and Research Centre, Dr. D. Y. Patil Vidyapeeth, Pune, Maharashtra, India
|Date of Web Publication||22-Dec-2015|
Akshay Ajit Shah
Department of Radio-Diagnosis, Dr. D. Y. Patil Medical College, Pimpri, Pune - 411 018, Maharashtra
Source of Support: None, Conflict of Interest: None
Pulmonary hypoplasia is a bronchopulmonary foregut anomaly characterized by a decrease in the number or size of airways, vessels, and alveoli. Unilateral pulmonary hypoplasia is a rare congenital anomaly, which is frequently associated with other congenital anomalies. Clinical symptoms vary depending on the other system anomalies and severity of pulmonary hypoplasia. Although it is usually diagnosed in infancy and childhood, some cases do not show any symptoms until the adolescent ages. A case of the right-sided pulmonary hypoplasia is described. A 20-year-old male was referred to our department with complaints of cough, breathlessness and right sided chest pain. Chest roentgenogram showed a homogeneous opacity, shifting of the mediastinum, and narrowing of intercostal spaces on the right and an overinflated left lung. Computed tomography scan of the thorax confirmed the diagnosis of right-sided pulmonary hypoplasia. It was not associated with any other developmental anomaly.
Keywords: Computed tomography thorax, hypoplasia, pulmonary, unilateral, X-ray
|How to cite this article:|
Shah AA, Singh AR, Kharat AT. Unilateral pulmonary hypoplasia in an adult
. Med J DY Patil Univ 2016;9:110-3
| Introduction|| |
Hypoplasia of lung is a rare congenital anomaly in which gross morphology of the lung is preserved, but there is a decrease in number or size of airways, vessels, and alveoli. The developmental anomalies of the lung at the 4 th and 24 th weeks of gestation may cause bronchopulmonary foregut abnormalities. Most patients described in the literature are newborns and infants.  The incidence of unilateral pulmonary hypoplasia has been estimated approximately one in 15,000 live births,  or between 0.0034% and 0.0097%  without sex predilection.  The right and left lung are affected with equal frequency. ,, Right pulmonary hypoplasia/agenesis has an increased association with other congenital anomalies involving the cardiovascular system (tetralogy of Fallot), , gastrointestinal tract, central nervous system (anencephaly and hydrocephaly),  genitourinary tract, musculoskeletal anomalies of thoracic cage, Klippel-Feil syndrome, and Down syndrome.  Bronchiectatic changes have also been reported in the hypoplastic lung. 
| Case Report|| |
A 20-year-old male was admitted in D. Y. Patil Hospital and Research Centre, Pimpri, Pune, with chief complaints of cough, breathlessness increased on exertion, and dull aching pain over the right side of the chest for 2 years.
Chest X-ray showed a right-sided homogeneous opacity, shifting of the mediastinum, and chest retraction. The intercostal spaces on the right side were narrowed. Left lung was overinflated [Figure 1]. The lesions were nonprogressive on serial chest X-rays.
|Figure 1: Chest X-ray shows a right-sided homogeneous opacity, shifting of the mediastinum, and chest retraction. The intercostal spaces on the right side are narrowed. Left lung was overinflated|
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Computed tomography (CT) scan thorax revealed marked asymmetry in thorax. The left lung showed a herniation through anterior recess. Evidence of a significant reduction in right lung volume suggestive of hypoplasia with compensatory hypertrophy of left lung [Figure 2] and [Figure 3]. The right upper lobe bronchus was absent; with narrowing of right main stem bronchus, middle and lower lobe bronchi and their subsequent segmental, and subsegmental divisions [Figure 4] and [Figure 5]. The trachea was deviated to the right. The mediastinum was seen to be significantly shifted to the right side [Figure 6].
|Figure 2: Evidence of a signifi cant reduction in right lung volume suggestive of hypoplasia, with compensatory hypertrophy of left lung|
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|Figure 3: Computed tomography with volume rendering shows the hypoplasia of the right lung and compensatory hypertrophy of left lung|
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|Figure 4: Axial image of the lung shows narrowing of right main stem bronchus and a normal left main stem bronchus|
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|Figure 5: Sagittal image of the lung shows narrowing of right main stem bronchus|
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|Figure 6: Coronal section shows the significant shift of the mediastinum to the right|
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| Discussion|| |
Development of the bronchial tree takes place at about 26 th to 31 st day of intrauterine life. Monaldi divided the mal-development of lung in four groups.  Group I: No bifurcation of trachea; Group II: Only rudimentary main bronchus; Group III: Incomplete development after division of main bronchus; and Group IV: Incomplete development of subsegmental bronchi and small segment of the corresponding lobe. The present case belongs to the fourth group of Monaldi classification.
According to Boyden,  there are three degrees of mal-development:
Our case belongs to the third degree of mal-development according to Boyden classification.
- Agenesis, in which there is complete absence of lung tissue,
- Aplasia, in which rudimentary bronchus is present but no lung tissue is present, and
- Hypoplasia, in which all the normal pulmonary tissues are present, but are under-developed.
Hypoplasia of the lung may be regarded as primary (idiopathic) or secondary (when it occurs in association with environmental factors or other congenital anomalies that may be implicated in its pathogenesis).
Primary pulmonary hypoplasia may be caused by deficient thyroid transcription factor 1, GATA factors, hepatocyte nuclear factor (HNF310), epidermal growth factor and its receptor; mitogen-activated protein kinase.  More commonly, it is secondary arising as a result of small fetal thoracic volume, prolonged oligohydramnios, early rupture of membranes at 15-28 weeks gestation,  longer latent period before delivery, decreased fetal breathing, decreased pulmonary perfusion, congenital heart diseases, and trisomies 18, 13, 21.  The incidence of secondary form is difficult to determine; however, because of its association with a variety of other abnormalities and the difficulty of pathologic diagnosis in some cases, it is likely to be more common than generally recognized. The incidence of primary hypoplasia has been estimated to be one per 15,000 births.
Radiographic findings in cases of hypoplasia are similar and characterized principally by almost total absence of aerated lung in one hemi-thorax. The markedly reduced volume is indicated by approximation of ribs, elevation of ipsilateral diaphragm, and shift of the mediastinum. In most cases, the contralateral lung is greatly over-inflated and displaced along with anterior mediastinum into the involved hemi-thorax; this displacement of air containing lung to the side of involved lung may lead to some confusion in diagnosis. CT scan may be required to establish the degree of underdevelopment and to differentiate hypoplasia from other conditions that may closely mimic it radiographically: Atelectasis from other causes, severe bronchiectasis with collapse and advanced pulmonary fibrosis. Main differential diagnosis of hypoplastic lung is Swyer-James syndrome. Swyer-James syndrome is an uncommon abnormality characterized radiologically by hyperlucent lobe or lung and functionally by air trapping during expiration. There is substantial evidence that the syndrome is initiated by viral bronchiolitis. Although both conditions are associated with unilateral very low volume, patients with Swyer-James syndrome characteristically demonstrate an air trapping on radiographs or HRCT scans performed at the end of maximal expiration. 
Diagnosis of unilateral pulmonary hypoplasia requires a high index of clinical suspicion and experience with reading radiographs. The radiographic findings will vary depending on the extent of lung involvement and chest CT or magnetic resonance imaging may be needed to better diagnose this condition. The natural history in this case illustrates the importance of diagnosis of this condition by keeping it in mind as a differential diagnosis in cases where unilateral homogenous opacity is noted on chest radiographs. Furthermore, a thorough congenital anomaly scan during 18-22 weeks of pregnancy may help in early diagnosis of pulmonary hypoplasia and help in better management of this condition.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]