There are four main types of<unk> , three of which are related to the anatomy of the lobules of the lung – centrilobular or centriacinar, panlobular or panacinar, and paraseptal or distal acinar and are not associated with fibrosis (scarring). Although fibrosis is not a normal feature of these subtypes, repair strategies in end-stage<unk>  may lead to pulmonary fibrosis. The fourth subtype is known as paracicatricial<unk>  or irregular<unk> , involves the acinus irregularly and is associated with fibrosis. Only the first two types of<unk>  – centrilobular, and panlobular are associated with significant airflow obstruction, with that of centrilobular<unk>  around 20 times more common than panlobular. The subtypes can be seen on imaging but are not well-defined clinically. There are also a number of associated conditions including bullous<unk> , focal<unk> , and Ritalin lung. Centrilobular<unk>  Centrilobular<unk>  also called centriacinar<unk> , affects the centre of a pulmonary lobule (centrilobular) in the lung, the area around the terminal bronchiole, and the first respiratory bronchiole, and can be seen on imaging as an area around the tip of the visible pulmonary artery. Centrilobular<unk>  is the most common type usually associated with smoking, and with chronic bronchitis. The disease progresses from the centrilobular portion, leaving the lung parenchyma in the surrounding (perilobular) region preserved. Usually the upper lobes of the lungs are affected. Panlobular<unk>  Panlobular<unk>  also called panacinar<unk>  affects all of the alveoli in a lobule and can involve the whole lung or mainly the lower lobes. This type of<unk>  is associated with alpha-1 antitrypsin deficiency (A1AD or AATD), and Ritalin lung, and is not related to smoking. Complications Likely complications of centrilobular, and panlobular<unk> , some of which are life-threatening, include: respiratory failure, pneumonia, respiratory infections, pneumothorax, interstitial<unk> , pulmonary heart disease, and respiratory acidosis. Paraseptal<unk>  Paraseptal<unk>  also called distal acinar<unk>  relates to<unk> tous change next to a pleural surface, or to a fissure. The cystic spaces known as blebs or bullae that form in paraseptal<unk>  typically occur in just one layer beneath the pleura. This distinguishes it from the honeycombing of small cystic spaces seen in fibrosis that typically occurs in layers. This type of<unk>  is not associated with airflow obstruction. Bullous<unk>  CT scan of bullous<unk>  When the subpleural bullae are significant, the<unk>  is called bullous<unk> . Bullae can become extensive and combine to form giant bullae. These can be large enough to take up a third of a hemithorax, compress the lung parenchyma, and cause displacement. The<unk>  is now termed giant bullous<unk> , more commonly called vanishing lung syndrome due to the compressed parenchyma. A bleb or bulla may sometimes rupture and cause a pneumothorax. Stained lung tissue from end-stage<unk> . Paracicatricial<unk>  Paracicatricial<unk> , also known as irregular<unk> , is seen next to areas of fibrosis (scarring) as large spaces. The scarring is most often a result of silicosis, granulomatous infection, tuberculosis, or pulmonary infarction. It can be difficult to differentiate from the honeycombing of pulmonary fibrosis. HIV associated<unk>  Classic lung diseases are a complication of HIV/AIDS with<unk>  being a source of disease. HIV is cited as a risk factor for the development of<unk> , and COPD regardless of smoking status. Around 20 percent of those with HIV have increased<unk> tous changes. This has suggested that an underlying mechanism related to HIV is a contributory factor in the development of<unk> . HIV associated<unk>  occurs over a much shorter time than that associated with smoking; an earlier presentation is also seen in<unk>  caused by alpha-1 antitrypsin deficiency. Both of these conditions predominantly show damage in the lower lungs which suggests a similarity between the two mechanisms. Alpha-1 related<unk> <unk>  may develop in some people with alpha-1 antitrypsin deficiency, the only genotype of chronic obstructive pulmonary disease. This usually occurs a lot earlier, as does HIV associated<unk>  than other types. Ritalin lung The intravenous use of methylphenidate, commonly marketed as Ritalin and widely used as a stimulant drug in the treatment of attention deficit hyperactivity disorder, can lead to<unk> tous changes known as Ritalin lung. The mechanism underlying this link is not clearly understood. Ritalin tablets contain talc as a filler, and these need to be crushed and dissolved for injecting. It has been suggested that the talc exposure causes granulomatosis leading to alveolar destruction. However, other intravenous drugs also contain talc and there is no associated<unk> tous change. High resolution CT scanning shows the<unk>  to be panlobular. CPFE Combined pulmonary fibrosis and<unk>  (CPFE) is a rare syndrome that shows upper-lobe<unk> , together with lower-lobe interstitial fibrosis. This is diagnosed by CT scan. This syndrome presents a marked susceptibility for the development of pulmonary hypertension. Congenital lobar<unk>  Congenital lobar<unk>  (CLE), also known as congenital lobar overinflation and infantile lobar<unk> , is a neonatal condition associated with enlarged air spaces in the lungs of newborn infants. It is diagnosed around the time of birth or in the first 6 months of life, occurring more often in boys than girls. CLE affects the upper lung lobes more than the lower lobes, and the left lung more often than the right lung. CLE is defined as the hyperinflation of one or more lobes of the lung due to the partial obstruction of the bronchus. This causes symptoms of pressure on the nearby organs. It is associated with several cardiac abnormalities such as patent ductus arteriosus, atrial septal defect, ventricular septal defect, and tetralogy of Fallot. Although CLE may be caused by the abnormal development of bronchi, or compression of airways by nearby tissues, no cause is identified in half of cases. CT scan of the lungs is useful in assessing the anatomy of the lung lobes and status of the neighbouring lobes on whether they are hypoplastic or not. Contrast-enhanced CT is useful in assessing vascular abnormalities and mediastinal masses. Focal<unk>  A large bulla and a smaller bleb illustrated Focal<unk> , is a localized region of<unk>  in the lung that is larger than alveoli, and often associated with coalworker's pneumoconiosis. This is also known as localized pulmonary<unk> . Blebs and bullae may also be included as focal<unk> . These can be differentiated from the other type of enclosed air space known as a lung cyst by their size and wall thickness. A bleb or bulla has a wall thickness of less than 1 mm, and are smaller. Occupational<unk>  A number of occupations are associated with the development of<unk>  due to the inhalation of varied gases and particles. In the US uranium mining that releases radon gas and particles has been shown to be a cause of<unk>  deaths; the figures in the study included some miners who also smoked. Uranium mining and milling was found to create environmental pollution. The inhalation of coal mine dust that can result in coalworker's pneumoconiosis is an independent risk factor for the development of<unk> . Focal<unk>  is associated with the coal macule, and this extends into progressive centrilobular<unk> . Less commonly a variant of panlobular<unk>  develops. Silicosis results from the inhalation of silica particles, and the formation of large silica nodules is associated with paracicatricial<unk> , with or without bullae. Ozone-induced<unk>  Ozone is another pollutant that can affect the respiratory system. Long-term exposure to ozone can result in<unk> .
Emphysema
Pleurisy
Plastic bronchitis
Atelectasis
Empyema
Reactive airway disease
Bronchiectasis
Acute bronchitis