Idiopathic Pulmonary Fibrosis

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Annotated Information

Classification and Resources

ID 53
ICD-10
ICD-9-CM
OMIM OMIM:178500;
SNOMED-CT
Orphanet
MeSH MSH:D054990;
DO

Defination

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 dyspnea (shortness of breath) Fibrosis is usually associated with a poor prognosis~IPF belongs to a large group of more than 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 and 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~Treatment may include nintedanib or pirfenidone~

Synonyms

cryptogenic fibrosing alveolitis  ; FIBROCYSTIC PULMONARY DYSPLASIA  ; IDIOPATHIC PULMONARY FIBROSIS, FAMILIAL  ;

Etiology

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Diagnosis

An earlier diagnosis of IPF is a prerequisite for earlier treatment and, potentially, improvement of the long-term clinical outcome of this progressive and ultimately fatal disease If IPF is suspected, diagnosis can be challenging but a multidisciplinary approach involving a pulmonologist, radiologist and pathologist expert in interstitial lung disease has been shown to improve the accuracy of IPF diagnosis~A Multidisciplinary Consensus Statement on the Idiopathic Interstitial Pneumonias published by the American Thoracic Society (ATS) and the European Respiratory Society (ERS) in proposed specific major and minor criteria for establishing the diagnosis of IPF However, in , new simplified and updated criteria for the diagnosis and management of IPF were published by the ATS, ERS, together with the Japanese Respiratory Society (JRS) and Latin American Thoracic Association (ALAT) Currently, a diagnosis of IPF requires:~Exclusion of known causes of ILD, eg, domestic and occupational environmental exposures, connective tissue disorders, or drug exposure/toxicity~The presence of a typical radiological UIP pattern on 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~Recognizing IPF in clinical practice can be challenging as symptoms often appear similar to those of more common diseases, such asthma, chronic obstructive pulmonary disease (COPD) and congestive heart failure (wwwdiagnoseipfcom) The key issue facing clinicians is whether the presenting history, symptoms (or signs), radiology, and pulmonary function testing are collectively in keeping with the diagnosis of IPF or whether the findings are due to another process It has long been recognized that patients with ILD related to asbestos exposure, drugs (such as chemotherapeutic agents or nitrofurantoin), rheumatoid arthritis and scleroderma/systemic sclerosis may be difficult to distinguish from IPF Other differential diagnostic considerations include interstitial lung disease related to mixed connective tissue disease, advanced sarcoidosis, chronic hypersensitivity pneumonitis, pulmonary Langerhan’s cell histiocytosis and radiation-induced lung injury~Radiology[edit]~Chest X-rays are useful in the follow up routine of IPF patients Plain chest X-rays are unfortunately not diagnostic but may reveal decreased lung volumes, typically with prominent reticular interstitial markings near the lung bases~The radiological evaluation through HRCT is an essential point in the diagnostic pathway in IPF HRCT is performed using a conventional computed axial tomographic scanner without injection of contrast agents Evaluation slices are very thin, –?mm~Typical HRCT of the chest of IPF demonstrates fibrotic changes in both lungs, with a predilection for the bases and the periphery According to the joint ATS/ERS/JRS/ALAT guidelines, HRCT is an essential component of the diagnostic pathway in IPF which can identify UIP by the presence of:~Reticular opacities, often associated with traction bronchiectasis~Honeycombing manifested as cluster cystic airspaces, typically of comparable diameters (–?mm) but occasionally large Usually sub-pleural and characterized by well-defined walls and disposed in at least two lines Generally one line of cysts is not sufficient to define honeycombing~Ground-glass opacities are common but less extensive than the reticulation~Distribution characteristically basal and peripheral though often patchy~Histology[edit]~According to the updated guidelines, in the absence of a typical UIP pattern on HRCT, a surgical lung biopsy is required for confident diagnosis~Histologic specimens for the diagnosis of IPF must be taken at least in three different places and be large enough that the pathologist can comment on the underlying lung architecture Small biopsies, such as those obtained via transbronchial lung biopsy (performed during bronchoscopy) are usually not sufficient for this purpose Hence, larger biopsies obtained surgically via a thoracotomy or thoracoscopy are usually necessary~Lung tissue from people with IPF usually show a characteristic histopathologic UIP pattern and is therefore the pathologic counterpart of IPF Although a pathologic diagnosis of UIP often corresponds to a clinical diagnosis of IPF, a UIP histologic pattern can be seen in other diseases as well, and fibrosis of known origin (rheumatic diseases for example) There are four key features of UIP including interstitial fibrosis in a ‘patchwork pattern’, interstitial scarring, honeycomb changes and fibroblast foci~Fibroblastic foci are dense collections of myofibroblasts and scar tissue and, together with honeycombing, are the main pathological findings that allow a diagnosis of UIP~Bronchoalveolar lavage[edit]~Bronchoalveolar lavage (BAL) is a well-tolerated diagnostic procedure in ILD BAL cytology analyses (differential cell counts) should be considered in the evaluation of patients with IPF at the discretion of the treating physician based on availability and experience at their institution BAL may reveal alternative specific diagnoses: malignancy, infections, eosinophilic pneumonia, histiocytosis X, or alveolar proteinosis In the evaluation of patients with suspected IPF, the most important application of BAL is in the exclusion of other diagnoses Prominent lymphocytosis (>%) generally allows excluding a diagnosis of IPF~Pulmonary function tests[edit]~Spirometry classically reveals a reduction in the vital capacity (VC) with either a proportionate reduction in airflows, or increased airflows for the observed vital capacity The latter finding reflects the increased lung stiffness (reduced lung compliance) associated with pulmonary fibrosis, which leads to increased lung elastic recoil~Measurement of static lung volumes using body plethysmography or other techniques typically reveals reduced lung volumes (restriction) This reflects the difficulty encountered in inflating the fibrotic lungs~The diffusing capacity for carbon monoxide (DLCO) is invariably reduced in IPF and may be the only abnormality in mild or early disease Its impairment underlies the propensity of patients with IPF to exhibit oxygen desaturation with exercise which can also be evaluated using the -minute walk test (MWT)~Terms such as ‘mild’, ‘moderate’, and ‘severe’ are sometimes used for staging disease and are commonly based on resting pulmonary function test measurements However, there is no clear consensus regarding the staging of IPF patients and what are the best criteria and values to use Mild-to-moderate IPF has been characterized by the following functional criteria:~Forced Vital Capacity (FVC) of ≥%~DLCO of ≥%~MWT distance ≥ meters~

Symptoms

An earlier diagnosis of IPF is a prerequisite for earlier treatment and, potentially, improvement of the long-term clinical outcome of this progressive and ultimately fatal disease If IPF is suspected, diagnosis can be challenging but a multidisciplinary approach involving a pulmonologist, radiologist and pathologist expert in interstitial lung disease has been shown to improve the accuracy of IPF diagnosis~A Multidisciplinary Consensus Statement on the Idiopathic Interstitial Pneumonias published by the American Thoracic Society (ATS) and the European Respiratory Society (ERS) in proposed specific major and minor criteria for establishing the diagnosis of IPF However, in , new simplified and updated criteria for the diagnosis and management of IPF were published by the ATS, ERS, together with the Japanese Respiratory Society (JRS) and Latin American Thoracic Association (ALAT) Currently, a diagnosis of IPF requires:~Exclusion of known causes of ILD, eg, domestic and occupational environmental exposures, connective tissue disorders, or drug exposure/toxicity~The presence of a typical radiological UIP pattern on 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~Recognizing IPF in clinical practice can be challenging as symptoms often appear similar to those of more common diseases, such asthma, chronic obstructive pulmonary disease (COPD) and congestive heart failure (wwwdiagnoseipfcom) The key issue facing clinicians is whether the presenting history, symptoms (or signs), radiology, and pulmonary function testing are collectively in keeping with the diagnosis of IPF or whether the findings are due to another process It has long been recognized that patients with ILD related to asbestos exposure, drugs (such as chemotherapeutic agents or nitrofurantoin), rheumatoid arthritis and scleroderma/systemic sclerosis may be difficult to distinguish from IPF Other differential diagnostic considerations include interstitial lung disease related to mixed connective tissue disease, advanced sarcoidosis, chronic hypersensitivity pneumonitis, pulmonary Langerhan’s cell histiocytosis and radiation-induced lung injury~Radiology[edit]~Chest X-rays are useful in the follow up routine of IPF patients Plain chest X-rays are unfortunately not diagnostic but may reveal decreased lung volumes, typically with prominent reticular interstitial markings near the lung bases~The radiological evaluation through HRCT is an essential point in the diagnostic pathway in IPF HRCT is performed using a conventional computed axial tomographic scanner without injection of contrast agents Evaluation slices are very thin, –?mm~Typical HRCT of the chest of IPF demonstrates fibrotic changes in both lungs, with a predilection for the bases and the periphery According to the joint ATS/ERS/JRS/ALAT guidelines, HRCT is an essential component of the diagnostic pathway in IPF which can identify UIP by the presence of:~Reticular opacities, often associated with traction bronchiectasis~Honeycombing manifested as cluster cystic airspaces, typically of comparable diameters (–?mm) but occasionally large Usually sub-pleural and characterized by well-defined walls and disposed in at least two lines Generally one line of cysts is not sufficient to define honeycombing~Ground-glass opacities are common but less extensive than the reticulation~Distribution characteristically basal and peripheral though often patchy~Histology[edit]~According to the updated guidelines, in the absence of a typical UIP pattern on HRCT, a surgical lung biopsy is required for confident diagnosis~Histologic specimens for the diagnosis of IPF must be taken at least in three different places and be large enough that the pathologist can comment on the underlying lung architecture Small biopsies, such as those obtained via transbronchial lung biopsy (performed during bronchoscopy) are usually not sufficient for this purpose Hence, larger biopsies obtained surgically via a thoracotomy or thoracoscopy are usually necessary~Lung tissue from people with IPF usually show a characteristic histopathologic UIP pattern and is therefore the pathologic counterpart of IPF Although a pathologic diagnosis of UIP often corresponds to a clinical diagnosis of IPF, a UIP histologic pattern can be seen in other diseases as well, and fibrosis of known origin (rheumatic diseases for example) There are four key features of UIP including interstitial fibrosis in a ‘patchwork pattern’, interstitial scarring, honeycomb changes and fibroblast foci~Fibroblastic foci are dense collections of myofibroblasts and scar tissue and, together with honeycombing, are the main pathological findings that allow a diagnosis of UIP~Bronchoalveolar lavage[edit]~Bronchoalveolar lavage (BAL) is a well-tolerated diagnostic procedure in ILD BAL cytology analyses (differential cell counts) should be considered in the evaluation of patients with IPF at the discretion of the treating physician based on availability and experience at their institution BAL may reveal alternative specific diagnoses: malignancy, infections, eosinophilic pneumonia, histiocytosis X, or alveolar proteinosis In the evaluation of patients with suspected IPF, the most important application of BAL is in the exclusion of other diagnoses Prominent lymphocytosis (>%) generally allows excluding a diagnosis of IPF~Pulmonary function tests[edit]~Spirometry classically reveals a reduction in the vital capacity (VC) with either a proportionate reduction in airflows, or increased airflows for the observed vital capacity The latter finding reflects the increased lung stiffness (reduced lung compliance) associated with pulmonary fibrosis, which leads to increased lung elastic recoil~Measurement of static lung volumes using body plethysmography or other techniques typically reveals reduced lung volumes (restriction) This reflects the difficulty encountered in inflating the fibrotic lungs~The diffusing capacity for carbon monoxide (DLCO) is invariably reduced in IPF and may be the only abnormality in mild or early disease Its impairment underlies the propensity of patients with IPF to exhibit oxygen desaturation with exercise which can also be evaluated using the -minute walk test (MWT)~Terms such as ‘mild’, ‘moderate’, and ‘severe’ are sometimes used for staging disease and are commonly based on resting pulmonary function test measurements However, there is no clear consensus regarding the staging of IPF patients and what are the best criteria and values to use Mild-to-moderate IPF has been characterized by the following functional criteria:~Forced Vital Capacity (FVC) of ≥%~DLCO of ≥%~MWT distance ≥ meters~

Treatment

In many patients, symptoms are present for a considerable time before diagnosis The most common clinical features of IPF include the following:~Age over 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 (see image)~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~Assessment of “velcro” crackles on lung auscultation is a practical way to improve the earlier diagnosis of IPF Fine crackles are easily recognized by clinicians and are characteristic of IPFAdmin (talk)IPF Lung Sound~Sorry, your browser either has JavaScript disabled or does not have any supported player~You can download the clip or download a player to play the clip in your browser~velcro crackles on auscultation in a patient with IPF~~Problems playing this file? See media help~If bilateral fine crackles are present throughout the inspiratory time and are persisting after several deep breaths, and if remaining present on several occasions several weeks apart in a subject aged ≥ years, this should raise the suspicion of IPF and lead to consideration of an HRCT scan of the chest which is more sensitive than a chest X-ray As crackles are not specific for IPF, they must prompt a thorough diagnostic process~

Labs working on this disease

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References

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