Congenital lobar emphysema

A congenital lobar emphysema (CLE) refers to an over inflation of one or more lung lobes presumably due to various factors including a possible obstructive check valve mechanism at a bronchial level ².

Epidemiology

Congenital lobar emphysema is more common in males (M : F = 3 : 1) ⁵. 

Clinical presentation

Patients will typically have respiratory distress, most commonly in the neonatal period, and usually within the first 6 months of life ⁵. 

Pathophysiology

In congenital lobar emphysema, a lobe (or more) become distended and may or may not have more alveoli. There are many presumed mechanisms for progressive overdistension of a lobe including obstruction, cartilage deficiency, dysplasia, and immaturity. Most cases are idiopathic. 

Associations

A CLE can be associated with congenital heart defects such as :

• ventricular septal defect (VSD)
• patent ductus arteriosus (PDA) 
• tetralogy of Fallot 

Radiographic features

Interestingly there is quite a pronounced predilection for some lobes : 

• left upper lobe : most common ~ 40 - 45 % 
• right middle lobe : ~ 30 %
• right upper lobe : ~ 20 % 
• may involve more than a single lobe in ~ 5 %
• much rarer in the lower lobes.

Therefore despite the left upper lobe being most commonly affected, the right hemithorax is the most common side to be affected ⁶.

Plain film - chest radiograph

Immediate postpartum period 

The affected lobe tends to appear opaque and homogeneous because of fetal lung fluid or it may show a diffuse reticular pattern that represents distended lymphatic channels filled with fetal lung fluid.

Later findings

• appears as an area of hyperlucency in the lung with a paucity of vessels
• mass effect with mediastinal shift and hemidiaphragmatic depression
• decubitus films lying on the affected side will show little or no change in lung volume
• lateral film may demonstrate posterior displacement of the heart

CT chest

• shows above features in greater detail
• attenuation of vascular structures in affected lobe ⁴
• may also show compressive atelectasis of neighbouring lobes

Treatment

Mildly symptomatic patients are usually followed up. A lobectomy can be considered in severe cases ³. 

Differential diagnosis

• congenital cystic adenomatoid malformation (CCAM) / congenital pulmonary airway malformation (CPAM)
• pulmonary arterial hypoplasia
• pulmonary hypoplasia
• bronchial atresia : the distal to the atretic segment can have air trapping

See also

• differential for unilateral transradiant hemithorax