Pneumatosis

Pneumatosis is the abnormal presence of air or other gas within tissues. In the lungs, emphysema involves enlargement of the distal airspaces, and is a major feature of chronic obstructive pulmonary disease (COPD). Other pneumatoses in the lungs are focal (localized) blebs and bullae, pulmonary cysts and cavities. Pneumoperitoneum (or peritoneal emphysema) is air or gas in the abdominal cavity, and is most commonly caused by gastrointestinal perforation, often the result of surgery. Pneumarthrosis, the presence of air in a joint, is rarely a serious sign. A lung cyst, or pulmonary cyst, encloses a small volume of air, and has a wall thickness of up to 4 mm. A minimum wall thickness of 1 mm has been suggested, but thin-walled pockets may be included in the definition as well. Pulmonary cysts are not associated with either smoking or emphysema. A lung cavity has a wall thickness of more than 4 mm. Pneumothorax, air or gas in the pleural space Pneumomediastinum, air or gas in the mediastinum Also called mediastinal emphysema or pneumatosis/emphysema of the mediastinum Pneumoperitoneum (or peritoneal emphysema), air or gas in the abdominal cavity. The most common cause is a perforated abdominal viscus, generally a perforated peptic ulcer, although any part of the bowel may perforate from a benign ulcer, tumor or abdominal trauma. Pneumatosis intestinalis, air or gas cysts in the bowel wall Gastric pneumatosis (or gastric emphysema) is air or gas cysts in the stomach wall Pneumarthrosis is the presence of air in a joint. Its presentation on radiography is a radiolucent cleft often called a vacuum phenomenon, or vacuum sign. Pneumarthrosis is associated with osteoarthritis and spondylosis. Pneumarthrosis is a common normal finding in shoulders as well as in sternoclavicular joints. It is believed to be a cause of the sounds of joint cracking. It is also a common normal post-operative finding at least after spinal surgery. Pneumarthrosis is extremely rare in conjunction with fluid or pus in a joint, and its presence can therefore practically exclude infection.