<unk>  is a disease in which the normal lung architecture is replaced by a cavity.  In the healthy lung, oxygen transport occurs at the level of the alveoli which has an average size of 0.1 mm.  These air spaces can become enlarge by a number of processes: bacterial infection (Tuberculosis), fungal infection, vasculitis (Wegener's granulomatosis), collagen vascular disease (Sjögren's syndrome) or granulomatous disease (Sarcoidosis).
Cavitary pneumonia
Atypical pneumonia
Lung abscess
Viral pneumonia
Fungal pneumonia
Bacterial pneumonia
Round pneumonia
Trapped lung