<unk>  may be classified according to the etiology, anatomical location, and pathological course of the disease. Primary thoracic<unk>  occurs most commonly as iatrogenic<unk>  without associated pneumonia whereas secondary<unk>  happens more commonly secondary to pneumonia.<unk>  necessitans is a spontaneous  discharge of an<unk>  that has burrowed through the parietal<unk> into the chest wall to form a subcutaneous abscess that may eventually rupture through the skin.<unk>  is mostly caused by bacteria. It may be tuberculous or nontuberculous. Tuberculous<unk>  is the most common cause of<unk>  necessitans with majority of affected patients being immunocompromised. There are 3 stages of<unk>  which are important in terms of the laboratory findings. These are exudative, fibrinopurulent and organizing.
Pleural empyema classification
Pleural effusion classification
Hemothorax classification
Pneumothorax classification
Lung abscess classification
Farmer's lung differential diagnosis
Aspiration pneumonia classification
Pulmonary embolism classification