<unk>  is inflammation of the tissues in the mid-chest, or mediastinum. It can be either acute or chronic. It is thought to be due to four different etiologies: * direct contamination * hematogenous or lymphatic spread * extension of infection from the neck or retroperitoneum * extension from the lung or pleura Acute<unk>  is usually caused by bacteria and is most often due to perforation of the esophagus. As the infection can progress rapidly, this is considered a serious condition. Chronic sclerosing (or fibrosing)<unk> , while potentially serious, is caused by a long-standing inflammation of the mediastinum, leading to growth of acellular collagen and fibrous tissue within the chest and around the central vessels and airways. It has a different cause, treatment, and prognosis than acute infectious<unk> . Space infections: Pretracheal space – lies anterior to trachea. Pretracheal space infection leads to<unk> . Here, the fascia fuses with the pericardium and the parietal pleura, which explains the occurrence of empyema and pericardial effusion in<unk> . However, infectious of other spaces can also lead to<unk> .
Mediastinitis
Tonsillitis
Bronchitis
Tracheal tumor
Tracheitis
Lung abscess
Croup
Tracheobronchitis