Idiopathic Pulmonary Fibrosis
Idiopathic pulmonary fibrosis (IPF) is a chronic and ultimately fatal disease characterized by a progressive decline in lung function. The term pulmonary fibrosis means scarring of lung tissue and is the cause of worsening shortness of breath. Fibrosis is usually associated with a poor prognosis.
IPF belongs to a large group of more than 200 lung diseases known as interstitial lung diseases (ILDs), characterized by the involvement of lung interstitium. The interstitium, the tissue between the air sacs in the lung, is the primary site of injury in ILDs. However, these disorders frequently affect not only the interstitium, but also the airspaces, peripheral airways, and vessels. Lung tissue from people with IPF shows a characteristic histopathologic pattern known as usual interstitial pneumonia (UIP). UIP is therefore the pathologic counterpart of IPF. The term 'idiopathic' is used because the cause of pulmonary fibrosis is still unknown. IPF usually occurs in adult individuals of between 50 and 70 years of age, particularly those with a history of cigarette smoking, and affects more men than women. The diagnosis of IPF requires exclusion of other known causes of ILDs and the presence of a typical radiological pattern identified through high resolution computed tomography (HRCT). In the right clinical setting, it is possible to make the diagnosis of IPF by HRCT alone, obviating the need for surgical lung biopsy.
In many patients, symptoms are present for a considerable time before diagnosis. The most common clinical features of IPF include the following:
- Age over 50 years.
- Dry, non-productive cough on exertion.
- Progressive exertional dyspnea (shortness of breath with exercise).
- Dry, inspiratory bibasilar "velcro-like" crackles on auscultation (a crackling sound in the lungs during inhalation similar to Velcro being torn apart slowly, heard with a stethoscope).
- Clubbing of the digits, a disfigurement of the finger tips or toes.
- Abnormal pulmonary function test results, with evidence of restriction and impaired gas exchange.
These features are due to chronic oxygen deficiency in blood and can occur in a wide variety of other pulmonary disorders and not be specific for IPF. However, IPF should be considered in all patients with unexplained chronic exertional dyspnea who present with cough, inspiratory bibasilar crackles, or finger clubbing.
The cause of IPF is unknown but certain environmental factors and exposures have been shown to increase the risk. Cigarette smoking is the best recognized and most accepted risk factor for IPF, and increases the risk of IPF by about twofold. Other environmental and occupational exposures such as exposure to metal dust, wood dust, coal dust, silica, stone dust, biologic dusts coming from hay dust or mold spores or other agricultural products, and occupations related to farming / livestock have also been shown to increase the risk for IPF. There is some evidence that viral infections may be associated with idiopathic pulmonary fibrosis and other fibrotic lung diseases. Despite extensive investigation, the cause of IPF remains unknown. The fibrosis in IPF has been linked to cigarette smoking, environmental factors (e.g. occupational exposure to gases, smoke, chemicals or dusts), other medical conditions including gastroesophageal reflux disease (GERD), or to genetic predisposition (familial IPF). However, none of these is present in all people with IPF and therefore do not provide a completely satisfactory explanation for the disease. IPF is believed to be the result of an aberrant wound healing process including/involving abnormal and excessive deposition of collagen (fibrosis) in the pulmonary interstitium with minimal associated inflammation.
Asbestosis, Mesothelioma, Pulmonary Fibrosis and Idiopathic Pulmonary Fibrosis: Asbestosis is also known as Mesothelioma or Pulmonary Fibrosis. These diseases and their similarities are often subject to many clinical trials and studies to differentiate them from each other with some medical professionals disagreeing on their differences. Asbestosis generally progresses slowly, whereas malignant mesothelioma has an extremely poor prognosis. The treatment of patients with asbestos exposure and lung cancer is identical to that of any patient with lung cancer. Because exposure to cigarette smoke increases the risk of developing lung cancer in patients with a history of asbestos exposure, smoking cessation is essential. In many respects, asbestosis is clinically similar to idiopathic pulmonary fibrosis, but asbestosis usually progresses slowly, whereas idiopathic pulmonary fibrosis has a rapidly progressive course. No current treatment effectively alters the natural course of asbestosis.
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