Transient unilateral hyperlucent lung due to mucus plugs.

A 63-year-old patient with a tracheostomy presented with a transient unilateral hyperlucent lung and absent breath sounds over the left lower lobe. A tracheobronchial cast and an additional floating mucus plug in the left lower lobe bronchus were retrieved with fiberbronchoscopy. Subsequently normalisation of ventilation and radiological appearance of the left lung occurred.