to the lung, treatment can occasionally be curative but only in certain, rare circumstances. Benign tumors Benign tumors are relatively rare causes of respiratory disease. Examples of benign tumors are: Pulmonary hamartoma Congenital malformations such as pulmonary sequestration and congenital cystic adenomatoid malformation (CCAM). Pleural cavity diseases Pleural cavity diseases include pleural mesothelioma which are mentioned above. A collection of fluid in the pleural cavity is known as a pleural effusion. This may be due to fluid shifting from the bloodstream into the pleural cavity due to conditions such as congestive heart failure and cirrhosis. It may also be due to inflammation of the pleura itself as can occur with infection, pulmonary embolus, tuberculosis, mesothelioma and other conditions. A pneumothorax is a hole in the pleura covering the lung allowing air in the lung to escape into the pleural cavity. The affected lung "collapses" like a deflated balloon. A tension pneumothorax is a particularly severe form of this condition where the air in the pleural cavity cannot escape, so the pneumothorax keeps getting bigger until it compresses the heart and blood vessels, leading to a life-threatening situation. Pulmonary vascular disease Pulmonary vascular diseases are conditions that affect the pulmonary circulation. Examples are: Pulmonary embolism, a blood clot that forms in a vein, breaks free, travels through the heart and lodges in the lungs (thromboembolism). Large pulmonary emboli are fatal, causing sudden death. A number of other substances can also embolise (travel through the blood stream) to the lungs but they are much more rare: fat embolism (particularly after bony injury), amniotic fluid embolism (with complications of labour and delivery), air embolism (iatrogenic – caused by invasive medical procedures). Pulmonary arterial hypertension, elevated pressure in the pulmonary arteries. Most commonly it is idiopathic (i.e. of unknown cause) but it can be due to the effects of another disease, particularly COPD. This can lead to strain on the right side of the heart, a condition known as cor pulmonale. Pulmonary edema, leakage of fluid from capillaries of the lung into the alveoli (or air spaces). It is usually due to congestive heart failure. Pulmonary hemorrhage, inflammation and damage to capillaries in the lung resulting in blood leaking into the alveoli. This may cause blood to be coughed up. Pulmonary hemorrhage can be due to auto-immune disorders such as granulomatosis with polyangiitis and Goodpasture's syndrome. Neonatal diseases Pulmonary diseases also impact newborns and