Congenital Lobar Emphysema

The right middle lobe is hyperlucent, hyperexpanded with attenuated vascularity. It compresses adjacent parenchyma with RUL collapse.
CLE is a disorder affecting neonates and young infants and is usually associated with acute or subacute respiratory distress. Various bronchial and alveolar abnormalities can cause this disorder and in some cases the cause is unknown.
The most common detected abnormality is absence or hypoplasia of cartilage rings of major and branch bronchi with resultant bronchial collapse during exhalation. This results in inhalational air entry but collapse of the narrow bronchial lumen during exhalation. The bronchial obstruction leads to progressive hyperinflation and air trapping, usually involving only one pulmonary lobe.
CLE has two forms: hypoalveolar (fewer than expected number of alveoli) and polyalveolar (greater than expected number of alveoli).
Reference: Collins & Stern: Chest Radiology: The Essentials: 2008. Lippincott Williams & Wilkins
Credit: Dr Ahmed Haroun
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