<unk>  of the right lower lobe seen on chest X-ray. Clinically significant<unk>  is generally visible on chest X-ray; findings can include lung opacification and/or loss of lung volume. Post-surgical<unk>  will be bibasal in pattern. Chest CT or bronchoscopy may be necessary if the cause of<unk>  is not clinically apparent. Direct signs of<unk>  include displacement of interlobar fissures and mobile structures within the thorax, overinflation of the unaffected ipsilateral lobe or contralateral lung, and opacification of the collapsed lobe.In addition to clinically significant findings on chest X-rays, patients may present with indirect signs and symptoms such as elevation of the diaphragm, shifting of the trachea, heart and mediastinum; displacement of the hilus and shifting granulomas. Classification<unk>  of the middle lobe on a sagittal CT reconstruction.<unk>  may be an acute or chronic condition. In acute<unk> , the lung has recently collapsed and is primarily notable only for airlessness. In chronic<unk> , the affected area is often characterized by a complex mixture of airlessness, infection, widening of the bronchi (bronchiectasis), destruction, and scarring (fibrosis). Absorption (resorption)<unk>  The Earth's atmosphere is mainly composed of 78 vol. % nitrogen and 21 vol. % oxygen (+ 1 vol. % argon and traces of other gases). Since oxygen is exchanged at the alveoli-capillary membrane, nitrogen is a major component for the alveoli's state of inflation. If a large volume of nitrogen in the lungs is replaced with oxygen, the oxygen may subsequently be absorbed into the blood, reducing the volume of the alveoli, resulting in a form of alveolar collapse known as absorption<unk> . Compression (relaxation)<unk>  It is usually associated with accumulation of blood, fluid, or air within the pleural cavity, which mechanically collapses the lung. This is a frequent occurrence with pleural effusion, caused by congestive heart failure (CHF). Leakage of air into the pleural cavity (pneumothorax) also leads to compression<unk> . Cicatrization (contraction)<unk>  It occurs when either local or generalized fibrotic changes in the lung or pleura hamper expansion and increase elastic recoil during expiration. Causes include granulomatous disease, necrotising pneumonia and radiation fibrosis. Chronic<unk>  Chronic<unk>  may take one of two forms—middle lobe syndrome or rounded<unk> . Right middle lobe syndrome In right middle lobe syndrome, the middle lobe of the right lung contracts, usually because of pressure on the bronchus from enlarged lymph glands and occasionally a tumor. The blocked, contracted lung may develop pneumonia that fails to resolve completely and leads to chronic inflammation, scarring, and bronchiectasis. Patchy<unk>  Is due to lack of surfactant, as occurs in hyaline membrane disease of newborn or acute (adult) respiratory distress syndrome (ARDS). Rounded<unk>  In rounded<unk>  (folded lung or Blesovsky syndrome), an outer portion of the lung slowly collapses as a result of scarring and shrinkage of the membrane layers covering the lungs (pleura), which would show as visceral pleural thickening and entrapment of lung tissue. This produces a rounded appearance on X-ray that doctors may mistake for a tumor. Rounded<unk>  is usually a complication of asbestos-induced disease of the pleura, but it may also result from other types of chronic scarring and thickening of the pleura.
Atelectasis
Pleurisy
Emphysema
Lobar pneumonia
Pleural effusion
Pyelectasis
Hydrothorax
Atypical pneumonia