A<unk>  is a collection of blood within the tissue of the lung.  It may result when a<unk>  laceration fills with blood.  A lung laceration filled with air is called a pneumatocele.  In some cases, both pneumatoceles and<unk> s exist in the same injured lung.<unk> s take longer to heal than simple pneumatoceles and commonly leave the lungs scarred.  A<unk>  contusion is another cause of bleeding within the lung tissue, but these result from microhemorrhages, multiple small bleeds, and the bleeding is not a discrete mass but rather occurs in with the lung tissue.  An indication of more severe damage to the lung than<unk>  contusion, a<unk>  also takes longer to clear. Unlike contusions,<unk> s do not usually interfere with gas exchange in the lung, but they do increase the risk of infection and abscess formation.
Pulmonary hematoma
Hemothorax
Chylothorax
Urinothorax
Mediastinal hematoma
Hemopneumothorax
Hydropneumothorax
Pneumothorax