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. Lung cysts
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. Other thoracic
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

Abdominal
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

Joints
Pneumarthrosis is the presence of air in a joint.
Emicizumab (trade name Hemlibra) is a humanized bispecific antibody for the treatment of haemophilia A, developed by Genentech and Chugai (a subsidiary of Roche). A Phase I clinical trial found that it was well tolerated by healthy subjects.In November 2017, it was approved in the United States for treatment of haemophilia A in those who had developed resistance to other treatments. It was subsequently approved by the US FDA in April 2018 under the breakthrough therapy designation for treatment of haemophila A in those who have not developed resistance to other treatments. The U.S. Food and Drug Administration (FDA) considers it to be a first-in-class medication. Mechanism of action
Emicizumab binds to both the activated coagulation factor IX and to factor X, mediating the activation of the latter. This is normally the function of coagulation factor VIII, which is missing in haemophilia A patients. References
External links
"Emicizumab". Drug Information Portal. U.S. National Library of Medicine.