is generally known as PNEUMONIA, when it is due to infection; as ALVEOLITIS when the inflammation is immunological; and as PNEUMONITIS when it is due to physical or chemical agents.

consists of a collection of PUS within the lung tissue. Causes include inadequate treatment of pneumonia, inhalation of vomit, obstruction of the bronchial tubes by tumours and foreign bodies, pulmonary emboli (see EMBOLISM) and septic emboli. The patient becomes generally unwell with cough and fever. BRONCHOSCOPY is frequently performed to detect any obstruction to the bronchi. Treatment is with a prolonged course of antibiotics. Rarely, surgery is necessary.

is the accumulation of fluid in the pulmonary tissues and air spaces. This may be caused by cardiac disease (heart failure or disease of heart valves – see below, and HEART, DISEASES OF) or by an increase in the permeability of the pulmonary capillaries allowing leakage of fluid into the lung tissue (see ACUTE RESPIRATORY DISTRESS SYNDROME (ARDS)).

(left ventricular failure) can be caused by a weakness in the pumping action of the HEART leading to an increase in back pressure which forces fluid out of the blood vessels into the lung tissue. Causes include heart attacks and HYPERTENSION (high blood pressure). Narrowed or leaking heart valves hinder the flow of blood through the heart; again, this produces an increase in back pressure which raises the capillary pressure in the pulmonary vessels and causes flooding of fluid into the interstitial spaces and alveoli. Accumulation of fluid in lung tissue produces breathlessness. Treatments include DIURETICS and other drugs to aid the pumping action of the heart. Surgical valve replacement may help when heart failure is due to valvular heart disease.

complicates a variety of serious illnesses such as sepsis, trauma, aspiration of gastric contents and diffuse pneumonia. There is congestion throughout the lungs because of leakage of fluid through pulmonary capillaries. Treatment involves treating the cause and supporting the patient with intensive care, including artificial ventilation and oxygen.

may occur due to blockage of a bronchial tube by tumour, foreign body or a plug of mucus from bronchitis or pneumonia. Air beyond the blockage is absorbed into the circulation, causing the affected area of lung to collapse. Collapse may also occur when air is allowed into the pleural space – the space between the covering of the lung and the lining of the inside of the chest wall. This is called a pneumothorax, and may occur following trauma, or spontaneously – for example, when there is a rupture of a subpleural air pocket (such as a cyst), allowing a communication between the airways and the pleural space. Lung collapse by compression may occur when fluid collects in the pleural space (pleural effusion): when this fluid is blood, it is known as a haemothorax; if it is due to pus it is known as an empyema. Collections of air, blood, pus or other fluid can be removed from the pleural space by insertion of a chest drain, thus allowing the lung to re-expand.

are the most common form of cancer in men and, along with breast cancer, are also a major cause of cancer in women. Several types of lung cancer occur, the most common being squamous cell carcinoma, small- (or oat-) cell carcinoma, adenocarcinoma, and large-cell carcinoma. All but the adenocarcinoma are likely to have been caused by smoking. Each type has a different pattern of growth and responds differently to treatment. More than 35,000 men and women died of cancer of the lung in the UK in 2013.

The most common presenting symptom is cough; others include haemoptysis (coughing up blood), breathlessness, chest pain, wheezing and weight loss. As well as spreading locally in the lung – the rate of spread varies – lung cancer commonly spawns secondary growths in the liver, bones and brain. Diagnosis is confirmed by X-rays or scanning, and by bronchoscopy with BIOPSY.

may cause damage and, by admitting air into the pleural cavity, cause the lung to collapse with air in the pleural space (pneumothorax). This may require the insertion of a chest drain to remove the air from the pleural space and allow the lung to re-expand. The lung may be wounded by the end of a fractured rib or by some sharp object such as a knife pushed between the ribs.