Case No. :	23
Month :	November
Year :	2000
Contributor :	Dr. Swati Ugale

Clinical Profile | Radiological Findings | Discussion

Clinical Profile:
A 14 year-old-girl presented with recurrent cough & cold since childhood. On examination, air entry was grossly decreased on the left side of the chest. All hematological investigations were within normal limits.

Radiological Findings

A chest radiograph was obtained (Fig 1).

This shows a homogenous opacity involving the left mid & lower zones of the left lobe of the lung. There is compensatory emphysema of the remaining lung field and the opposite lung. Rib crowding & deformity were seen on the affected side.

A plain and contrast enhanced CT scan of the chest was then obtained (Fig 2,3,4).

 

This confirmed the findings on the chest radiograph. In addition, close apposition of the mediastinal structures to the antero-lateral chest wall was also seen. There is extrapleural soft tissue seen in the area that would otherwise have been occupied by the left upper lobe. The left lower lobe extends superiorly & shows compensatory emphysema. The left hilum was not visualized. The left main pulmonary artery is not visualized & the proximal left main bronchus is hypoplastic. There is no evidence of any focal parenchymal lesion in the visualized lung field and the pleura is normal. These radiological findings are consistent with the diagnosis of unilateral lobar primary pulmonary hypoplasia affecting the left upper lobe.

Differential Diagnosis and Discussion :

Unilateral absence of a lung / a lobe (hypoplsia) is a rare congenital abnormality. It is generally asymptomatic, detected at the adulthood or may be symptomatic(with the recurrent episodes of the wheezing/pneumonia ) and frequently associated with other congenital anomalies.. Men are more frequently affected than the women. The right lung is more commonly affected than the left. The common congenital anomaly associated with it is tracheo-esophageal fistula especially if the pulmonary pathology is on the right side. Left lung affection is associated with tracheo-esophageal fistulas without esophageal atresia. About 10% of patients with esophageal atresias have unilateral pulmonary agenesis.
Pulmonary hypoplasia found in 10% neonatal autopsies and 50% of these have associated congenital anomalies. During intrauterine life, fetal lung communicates freely with the amniotic sac & the fetus is known to exhibit breathing movements in the utero. Thus entry of the amniotic fluid into the lungs probably occurs. The fetal lung itself produces fluid as evidenced by expansile build up of the fluid behind a bronchial obstruction. The presence of the lung fluid & respiratory movements appears to play a role in the development of the normal lung. The most striking example of the influence of the fluid on the pulmonary embryogenesis is found in Potter's syndrome (oligohydramnios tetrad). In these infants, oligohydramnios is the result of the abnormal development of the urinary tract, mostly renal agenesis. The full tetrad comprises of- underlying renal abnormality causing oligohydramnios; abnormal facies resulting from the pressure effect in the utero and pulmonary hypoplasia.

More commonly, pulmonary hypoplasia is secondary to any condition that may causes stunted growth of the lung/lungs in the utero, e.g. congenital diaphragmatic hernia. The variation in the g degree of the pulmonary hypoplasia depends on the size of the hernia & the period during which the pressure effect on the lung were operative. In this condition, the basic problem being lack of the space for growth & the developing lung.

In pulmonary hypoplasia, following radiological findings are seen
The affected lung is small Affected lung/lobe shows n trace of the main bronchus - a bronchial bud may be seen
Bronchi form normal bronchial tree but end in the cavities (congenital cystic bronchiectasis) i.e. no alveoli.
Compensatory emphysema of the remaining lung / congenital emphysema
Displacement of the mediastinum fissures & diaphragm towards the affected area
The presence of the areolar tissue adjacent to the heart & the mediastinum frequently results in lack of definition of these bands on the affected side
Transradiant lung crossed by many vessels
Pulmonary vasculature is deformed /stunted

Conditions Associated With The Pulmonary Hypoplasia: