Idiopathic pulmonary fibrosis

Introduction to idiopathic pulmonary fibrosis Idiopathic pulmonary fibrosis (IPF) is a disease characterized by unclear etiology, diffuse alveolitis and alveolar structural disorders that ultimately lead to interstitial fibrosis. It is now considered to be related to immune damage. Typical IPF, mainly manifested as dry cough, progressive dyspnea, gradually worsened over several months or years, and progressed to end-stage respiratory failure or death within 3 to 8 years of symptoms. The main pathological features were pulmonary interstitial and alveolar spaces. Internal fibrosis and inflammatory cell infiltration are present in a mixture. Although the pathogenesis of the disease has not been fully elucidated, its clinical features and pathology are sufficient to show that this is a characteristic disease. The treatment of IPF still lacks objective and decisive prognostic factors or therapeutic response. Corticosteroids (hereinafter referred to as hormones) Or immunosuppressive agents, cytotoxic drugs are still the main therapeutic drugs, but less than 30% of patients have therapeutic response and can show toxic side effects. basic knowledge The proportion of sickness: 0.00025% Susceptible population: older men over the age of 60 are more common, have a history of smoking Mode of infection: non-infectious Complications: pneumothorax, lung cancer, pulmonary hypertension, pulmonary heart disease

Idiopathic pulmonary fibrosis

Immune and inflammatory response (30%):

The early stage of PF may produce an anti-specific immune response. The inflammatory response of the lower respiratory tract is the earliest detectable damage in the lungs, interstitial and alveolar lymphocytes, macrophages and neutrophils, and T lymphocytes in IPF. The regulation of lung injury and disease progression plays a dual role. The T lymphocytes obtained from the alveoli of IPF patients are activated, which can express IL-2 receptor and secrete INF-. The products secreted by T lymphocytes can inhibit fibroblasts. The proliferation of cells can also enhance the collagen synthesis of fibroblasts. In addition, T lymphocytes also have a huge auxiliary effect on B lymphocytes, which is important for enhancing the production of immune complexes.

The production of specific immune responses in the lung parenchyma is important for the accumulation of inflammatory cells that affect lung tissue. Selective adhesion molecules, adhesion molecule binding molecules and immunoglobulins play important roles in the interaction between inflammatory cells and endothelial cells. The strong adhesion of many cells depends on intercellular adhesion molecule-1 (ICAM-1) and leukocyte antigen-1 (LFA-1). TNF- induces ICAM-1 expression on the surface of endothelial cells. Extravascular leukocytes include LFA-1 and platelet endothelial cell adhesion molecules are expressed at the junction of leukocytes and endothelial cells, and urokinase-type plasminogen activator (urokinase u-PA) may be different during the movement of inflammatory cells from blood vessels to alveolar spaces. The degradation products of tissue proteolytic enzymes, the direct migration of inflammatory cells of IPF depend on a variety of chemicals, including chemokines interleukin-1 (IL-1) monocyte chemoattractant protein-1 (MCP-1), macrophages Inflammatory protein-Ia (MIP-1a), complement component C5a, cytokine (MCP-1, MIP-1a, fibronectin including RGD acting on macrophages, leukotriene B4 (LTB4), IL-8 and effects Leukocyte C5a, T lymphocytes, Macrophages, endothelial cells, epithelial cells, and fibroblasts are important sources of these cytokines, and urokinase receptors (u-PAR, CD87) are essential chemokines for monocytes and PMN, and U-PAR may Affects leukocyte circulation and activates the adhesion function of complement receptor 3.

Epithelial cell damage (30%):

Epithelial cell damage is a hallmark of IPF. Viral infection and inflammatory cell products (oxygen free radicals, proteolytic enzymes) are mediators of damage. Epithelial cell damage causes plasma proteins to exude into the alveolar space. During the injury process, the alveolar basal layer also The presence of destructible, activated inflammatory cells (lymphocytes, macrophages, PMN) contributes to the continuous development of alveolar wall damage.

Alveolar repair (15%):

Successful repair of damaged alveoli requires removal of plasma proteins entering the alveolar space, replacing the damaged alveolar wall, re-storing the damaged extracellular matrix, and alveolar exudate formed during inflammatory reactions including many cytokines and media such as growth factors (platelet growth). Factor, metastatic growth factor-, insulin-like growth factor-I), fibronectin, thromboxane, fibrin peptide, etc., alveolar epithelial cells and macrophages regulate the formation and clearance of cellulose in the alveoli due to the presence of -PA There is reticular fibrin degradation activity in the alveolar cavity. However, fibrin degradation activity in BAL of IPF patients is due to plasminogen activator and plasmin such as plasminogen activator inhibitor-1 (PAI-1). The level is increased and inhibited. Similarly, fibronectin in the alveolar space is also inhibited. If the exudate in the alveoli is not removed, the fibroblasts will invade and proliferate, producing new matrix proteins, making the fiber rich. The exudate of the prime becomes a scar.

Fibrosis (10%):

Arachidonic acid metabolism also plays an important role in the fibrosis reaction of IPF. Interleukin has a direct effect on fibroblasts and other mesenchymal cells, stimulates fibroblasts to release chemokines, promote cell proliferation and collagen synthesis, and alveolar repair. An important feature of the epithelial remodeling of the alveolar basement membrane, in order to complete this process, type II alveolar epithelial cells proliferate, the final basement membrane surface repair, local exudate mechanization, this process is undoubtedly in keratinocyte growth factor Under the influence of hepatocyte growth factor, these two factors regulate epithelial cell proliferation and migration.

During the formation of IPF, epithelial cells are missing, alveolar collapses, and a mass of scars is formed when a large number of alveoli are involved.

Pathogenesis

Histology of lung biopsy specimens is important to rule out other diagnoses and quantification of fibrosis and inflammation. The main pathological features of IPF include alveolar septum (interstitial) and alveolar fibrosis and inflammation at different degrees because of many inflammatory properties. Pulmonary diseases can have similar manifestations, so granulomas, vasculitis, inorganic pneumoconiosis or organic pneumoconiosis must be ruled out. The pathological changes of IPF are diverse and distributed in patches, mostly in the periphery of the lungs ( Subpleural), even in the severely affected lung lobe, some alveoli can be protected from involvement. In the early stage of the disease, the alveolar structure can remain intact, but the alveolar wall edema thickens, and the interstitial inflammatory cells accumulate, mainly monocytes ( Such as lymphocytes, plasma cells, monocytes, macrophages, but also scattered polynuclear neutrophils and eosinophils.

In the early stage of the disease, alveolar macrophages are focally clustered, and alveolar macrophages in moderate or advanced IPF are absent. As the disease progresses, chronic inflammatory infiltration becomes less and less obvious, and the alveolar structure is densely fibrous. Instead, the alveolar wall breaks and breaks, leading to airway cystic dilatation (honeycomb lung), advanced disease, massive pulmonary collagen in the interstitial lung, intracellular matrix, fibroblasts, inflammatory cells are few or even absent, and the course of disease is longer. Alveolar epithelial hyperplasia, squamous metaplasia, some patients may have smooth muscle reactive hyperplasia, pulmonary artery dilatation, secondary pulmonary hypertension and other changes, airway can be distorted, leading to "traction bronchiectasis", such as smoking IPF The patient has a change in emphysema, which can distinguish between emphysema and honeycomb lung depending on the presence of fibrous tissue around the cystic cavity.

Diffuse alveolar damage is not a feature of early IPF, but can also be found in many other lung diseases such as adult respiratory distress syndrome (ARDS), inhaled lung injury, radiation-induced lung injury, drug-induced lung injury, collagen vascular disease, infection, etc.

I have previously subjectively divided IPF into several pathological subtypes, suggesting that desquamative interstitial pneumonia (DIP) and common interstitial pneumonia (UIP) are pathological types of IPF at different stages of the disease, according to the American Thoracic Society. (ATS) and the European Respiratory Society (ERS) have developed a new international consensus on the diagnosis of IPF: UIP is attributed to the specific pathological manifestations of IPF, while DIP, respiratory bronchitis (BPILD), non-specific interstitial pneumonia (NSIP), lymphocytic interstitial pneumonia (LIP), acute interstitial pneumonia (AIP), and bronchiolitis obliterans with organizing pneumonia (BOOP) are not IPF.

Idiopathic pulmonary fibrosis prevention

1. Due to the slow course of the disease, medical staff should carefully check and confirm the diagnosis.

2, to encourage patients to establish confidence in the fight against disease, and actively cooperate with treatment.

3, strengthen physical exercise, enhance disease resistance, winter should pay attention to keep warm.

4, pay attention to adjust diet, increase nutrition; smokers must quit smoking.

5, patients should be encouraged to participate in lung rehabilitation exercise programs such as walking every day, stepping on a fixed bicycle, etc., although can not increase lung capacity, but can change the tolerance of activities, reduce the symptoms of dyspnea, improve the quality of life.

Idiopathic pulmonary fibrosis complications Complications, pneumothorax, lung cancer, pulmonary hypertension, pulmonary heart disease

Complications may have secondary infections, spontaneous pneumothorax in pulmonary heart disease, and finally pulmonary fibrosis, leading to heart and lung failure, extensive pulmonary fibrosis is easy to be complicated by lung cancer, and pulmonary hypertension and pulmonary heart disease occur in advanced stages.

Idiopathic pulmonary fibrosis symptoms Common symptoms Sit-out breathing labor dyspnea dry cough joint sore pus side side thoracic collapse dyspnea respiratory failure weight loss appetite

Examination of idiopathic pulmonary fibrosis

Traditional laboratory tests are not specific for IPF, 60% to 94% of patients have elevated erythrocyte sedimentation rate, 10% to 20% of patients have circulating antinuclear antibodies or rheumatoid factor positive; 50% to 67% of patients can find circulating immunity Complexes, these indicators are not related to the extent and activity of the disease, nor can they predict treatment response.

Chest radiology

95% of patients with IPF have abnormal chest radiographs. The most common is lung volume reduction, double lung reticular or reticular nodular infiltrates, lesions are often diffuse, unilateral lesions are quite rare, and infiltrates are distributed in the periphery. Or the subpleural lung tissue, as the disease progresses, the lesion extends to the apex of the lung, and the lung volume is progressively reduced. If there is a light-transmitting area (cellular cavity) with a diameter of 3 to 5 mm on the chest piece, the fibrosis is implicated, and the alveolar structure is destroyed. The treatment response of this kind of lesion is poor. Individual patients can see interstitial infiltration, alveolar opaque area (glassy-like change), honeycomb lung, pleural effusion or intrathoracic lymph node enlargement is rare, traditional chest radiograph can not be alveolar Inflammation is distinguished from pulmonary fibrosis. It is not possible to accurately estimate the prognosis or hormone response. Patients with abnormal chest X-rays or asymptomatic or mild symptoms and normal chest X-ray should be thoroughly examined and found as early as possible to reverse IPF. process.

2. High resolution CT scan

High-resolution CT (HRCT) scans show that lung parenchyma of 1 to 2 mm is more sensitive than chest radiographs and is specific for clear IPF. HRCT scans are non-invasive and provide useful value for the extent and nature of lesions, IPF The lung lesions are flaky, and can also be extrapulmonary (subpleural) and atypical lesions at the base of both lungs. On HRCT, IPF lesions are characterized by local alveolar opaque areas (glassy-like changes), cystic Cavity, bronchial aeration, pleural adhesion, bronchial or pulmonary vascular irregularity or thickening, which is dominated by ground glass, reticular or honeycomb lesions, most of the IPF patients with mixed lesions, these performance Associated with histopathological changes, the ground-glass lesion is the shadow formed by the obstructed vascular shadow of the alveoli. These opaque alveolar regions (glass-like changes) are associated with cell biopsy specimens (active alveolitis), reticular lesions. It is characterized by a cross-line or thick line that reflects fibrosis; a small cell capsule (<5mm) is an alveolar septum, an inflammation of the alveolar duct and alveoli, and a bronchial aeration sign on HRCT represents an expanded branch surrounded by fibrotic lung tissue. gas Tubes (diameter 1 to 2 ram), cystic lesions larger than 5 mm are consistent with the honeycomb lungs seen during open lung biopsy. For end-stage IPF, HRCT and pathological examination can show dilated bronchus, significantly reduced Changes in anatomical structures such as lung volume, dilated pulmonary arteries, and emphysema in patients with smoking IPF (especially in the upper lobe of the lungs).

HRCT does not fully determine treatment response and prognosis assessment, but extensive ground-glass infiltration and small cellular changes can predict improvement in lung function parameters after hormone therapy (FEV1, FEV1%, DLCO). Conversely, cellular cystic changes indicate hormone therapy No response or minimal response, only a few patients with reticular lesions in the lungs responded to hormonal therapy. The series of HRCT showed that the ground-glass changes can be improved with the treatment, but also progress to reticular changes (no treatment Reactive patients), reticular changes often suggest treatment failure or disease progression, and cellular changes are almost always associated with progression or treatment non-response, so HRCT provides useful clinical and prognostic information for IPF, but further determination The prognosis or treatment response of IPF is not enough by HRCT alone, and other tests are needed.

3. Pulmonary function test and exercise test

(1) Pulmonary function tests: The physiological changes characteristic of IPF include a decrease in lung volume (eg, VC, TLC), a decrease in diffusion (DLCO), and hypoxemia (at rest and during exercise).

Expiratory flow rate (forced expiratory volume per second / forced vital capacity, ie FEV1/FVC) tends to increase, diffuse decrease, lung volume increases, indicating emphysema in addition to pulmonary fibrosis, if spirometry or flow rate - The volume curve suggests that the expiratory flow rate is normal or increased on the basis of tidal volume reduction. IPF should be suspected. More complex examinations include lung volume, diffusion (DLCO) and cardiopulmonary exercise tests, which are more sensitive than spirometers and have To help monitor the condition, DLCO is the most sensitive basic lung function parameter. Even when the lung volume is normal, DLCO can be reduced. DLCO is also a parameter for directly measuring pulmonary blood vessels. If the decrease of DLCO reflects the loss of capillary unit of alveolar wall, DLCO can be used. The lung volume (VA) was corrected to produce a DLCO / VA ratio, but the degree of tissue lesions was better correlated with DLCO than DLCO/VA.

Pulmonary function tests are valuable for assessing the extent of the lesion and assessing the efficacy. The relationship between specific examination of lung function and histological findings or treatment response is well defined. Lung volume reduction (less than 60% predicted) suggests prognosis and treatment. Poor response, but there are exceptions, DLCO decreased or severely impaired, mortality increased, patients with DLCO below 45% predicted, 3-year mortality greater than 50%, total lung volume change and histology, prognosis, survival rate There is no correlation. For a patient, there is no physiological indicator to distinguish alveolitis from fibrosis, and no potential therapeutic response can be expected. However, a series of physiological indicators after treatment is still very valuable. If there is no response after 3 months of hormone therapy, it is unlikely that the continuation of the hormonal condition will be improved.

(2) Exercise test gas exchange abnormalities (such as hypoxemia or alveolar-arterial oxygen pressure difference increase): is a sign of IPF, 85% IPF patients resting alveolar-arterial oxygen pressure difference [P (Aa) O2 Increased, increased during exercise is more obvious, exercise-induced alveolar-arterial oxygen pressure difference [P (Aa) O2] changes and physiological abnormalities are better than lung volume or DLCO.

Exercise tests provide an objective, repeatable indicator of disease severity. Typical changes include significantly limited exercise tolerance, increased [P(Aa)O2], respiratory alkalosis, decreased oxygen consumption, and ineffective lumen ventilation. (VD/VA) increases, the amount of ventilation per minute increases at a certain oxygen consumption level, and the pulse increases. The series of gas exchange indicators measured during exercise are the most sensitive indicators for monitoring the condition, and exercise tests (especially arterial intubation) Expensive, high technical requirements, and the examination is generally painful, elderly or debilitated patients are more difficult to accept, they can use less standard exercise test (6min walking test), ear or finger oxygen saturation results It is better to measure arterial blood gas directly, but it is more acceptable for patients. Although the application of the 6-min walk test is limited, it is acceptable as a quantitative indicator of disease progression or remission. More complicated tests such as lung compliance or pressure-volume The measurements help to assess the extent of the lesion, but they are invasive, have high professional requirements and are not suitable for many lung function room applications.

4. Clinical-radiology-physiological score

The clinical-radiology-physiological score (CPR) system turns clinical, radiological, and physiological into a composite score, seven variables including the degree of shortness of breath during exercise, chest X-ray findings, lung volume, vital capacity, DLCO, static P (Aa) O2 and arterial oxygen saturation, the CPR score has gradually improved the degree of disease. Each variable at different body weights allows a score to be determined to grade the disease. Open lung biopsy confirms CPR score and pathophysiological changes. The correlation is better than any of the individual indicators. The CPR score does not represent the activity of the disease, but it can provide an objective indicator of the extent and extent of the disease. It is useful in the series of evaluation of the degree of disease relief, because HRCT The score was more correlated with pathology than the chest radiograph, so we used a corrected CPR score instead of the general chest HRCT, but it is not optimistic that the scoring system lacks a valid prospective study.

5. Bronchoalveolar lavage

It is of great help in elucidating the role of important immune factors that contribute to the inflammatory response of IPF. These immune factors are derived from IPF, inflammatory responses, increased polynuclear neutrophils (PMNs), neutrophil products, and activated alveolar giants. Phagocytes, alveolar macrophage products, cytokines, growth factors and immune complexes are elevated. Although the value of BAL is used as a research tool, it also has a certain clinical value. 67% to 90% of IPF patients have BMN PMNs. Increased or increased eosinophils (or both); patients with elevated eosinophils in BAL have poor prognosis, and less than 15% of IPF patients have elevated lymphocytes in BAL. These patients have fewer cellular lungs and hormones. The treatment response is good, but the clinical value of BAL is limited for the staging or monitoring of IPF. BAL and series of bronchial biopsy cannot be used as diagnostic and evaluation tools.

6. Radionuclide imaging

Pulmonary Metabolic Imaging Lung Epithelial Cell Permeability Assay 67Ga lung scan can be used as adjunctive method to identify alveolitis because activated macrophages and other inflammatory cells contribute to the uptake of 67Ga, IPF, sarcoidosis and various inflammations. The increase of 67Ga in the lungs of sexually transmitted diseases has a strong correlation with the lesions of lung biopsy specimens. However, even if it is very carefully quantified (the logarithm calculation is difficult), the 67Ga scan cannot predict the treatment response and clinical course, and Expensive, complicated inspection (scanning should be carried out 48 hours after injection), patients and staff are exposed to radiation radiation, although people initially have a high enthusiasm for 67Ga scanning, but it still has no IPF staging and disease monitoring How much value.

Other radionuclide scans have also been used to evaluate the activity of IPF, and positron emission tomography (PET) has shown that patients with active pulmonary interstitial disease have beta-alanine valeric acid (DTPA, a measure of alveolar epithelial permeability). Increased clearance rate of 18F-deoxyglucose metabolism, ferritin, a substance that measures pulmonary capillary permeability, increased pulmonary capillary permeability, studies have shown that Tc-DTPA clearance is increased Or 18F-deoxyglucose metabolism levels continue to indicate clinical deterioration, 99mTc-DTPA aerosol inhalation scan to measure the permeability of alveolar epithelium, can be used as a quantitative indicator of lung inflammation, but PET inspection operations are complex, expensive, still need Further research observation.

7. Lung biopsy

The best biopsy method for IPF is controversial. Surgical lung biopsy (thoracic or thoracoscopic) is considered the gold standard for diagnosis, and flexible bronchoscopy lung biopsy (IBLR) can be performed on outpatients. Low, TBLR should be performed in patients with interstitial lung disease before thoracotomy or thoracoscopic lung biopsy. TBLR can identify a large number of specific diagnoses other than IPF (eosinophilic granuloma, sarcoidosis, malignancy, allergy) Pneumonia, infection, obliterative bronchiolitis, eosinophilic pneumonia, alveolar proteinosis, etc.), because the tissue specimen taken by TBLR is small (2 ~ 5mm), the degree of fibrosis cannot be determined, when TBLR is not clear At the time of diagnosis, a video-assisted thoracoscopic lung biopsy should be performed to exclude non-specific diseases.

Surgical lung biopsy (such as thoracotomy or video-assisted thoracoscopic surgery) can more accurately distinguish the extent of inflammation and fibrosis, and has a diagnostic value for alveolar inflammation (alveolitis) activity and end-stage pulmonary fibrosis (honeycomb lung). To obtain a representative specimen of the lung, biopsy should be performed at least in two different sites. Generally, biopsy should be avoided in the most severe lesions. Specimens should be taken in moderately affected and unaffected areas to determine the type and progression of the disease. To the extent, take 2 or 3 tissue specimens in the upper or lower lobe of the ipsilateral lung, and avoid the apex or middle lobe, as non-specific scars or inflammation often involve these sites.

Even with surgical lung biopsy, it is difficult to evaluate the prognosis of different IPF patients due to changes in the degree of fibrosis of the leaves and leaves (even the same lobe). Semi-quantitative scoring systems and morphometric analysis techniques have been used to more accurately evaluate fibrosis. And the degree of inflammation, this complex scoring system can comprehensively grade the fibrosis process, cell composition, inflammation range and specific parts (alveolar wall, alveolar cavity, airway), certain histological features (such as Alveolar wall metaplasia, smooth muscle and vascular changes are associated with cellular lung and fibrotic lesions. It is now advocated to distinguish neonatal connective tissue from end-stage fibrosis (cellular lung changes), but the problem is even the most experienced Pathologists, the results observed by different people are very different, whether the use of such a complex scoring system can improve the value of lung biopsy evaluation of disease prognosis, there is no research in this area.

The flexible method of biopsy is reasonable. It is not conclusive to decide when to perform lung biopsy. Most patients should undergo surgical open lung biopsy. Video-assisted thoracoscopic lung biopsy can also be considered. Low specific mortality, short chest drainage time, and low hospitalization days, patients who are at greater risk of surgery (eg, older than 70 years, extremely obese, with heart disease, severely impaired lung function), when other characteristics are met At the time of IPF, transbronchial lung biopsy under fiberoptic bronchoscopy may also be considered.

Diagnosis and differentiation of idiopathic pulmonary fibrosis

diagnosis

(1) Diagnostic technology

1. Imaging examination:

(1) Conventional X-ray: The radiography technique should pay attention to proper penetration conditions, apply a moderately sensitized screen, and focus should be small. The early alveolitis can not show abnormalities on the X-ray; as the lesion progresses, the X-ray shows a cloud-like appearance. Visible faintly visible diffuse shadows are like grinding glass. Further progress shows that fibrosis becomes more and more obvious, from slender woven to coarse woven, or reticulated, and later in size. The cystic changes, such as the honeycomb lung, the lung volume is reduced, the diaphragm is lifted, and the interlobular fissure is displaced.

(2) CT contrast resolution is better than X-ray. High resolution CT (HRCT) can further improve spatial resolution. It is very helpful for the diagnosis of IPF, especially the identification of early alveolitis and fibrosis and the discovery of honeycomb lung.

(3) Radionuclide IPF often has increased permeability of alveolar capillary membrane, and radionuclide technique inhalation of 99mTc-DTPA aerosol to measure lung epithelial permeability (LEP) shows T1/2 shortening, which is helpful for early detection and diagnosis of interstitial Sexual lung disease, not specific for IPF.

2. Pulmonary function tests: typical pulmonary function changes of IPF include restricted ventilatory damage, decreased lung capacity, decreased lung compliance and decreased diffuse volume, severe PaO2 decline and PA-aO2 broadening, pulmonary function tests and imaging techniques. It is helpful for early diagnosis, especially in exercise test. There is a decrease in diffusion and hypoxemia before the occurrence of imaging abnormalities. Pulmonary function tests can be used for dynamic observation, which is helpful for the evaluation of the condition. It may also be useful for assessing the efficacy. Similarly, IPF's pulmonary dysfunction is not specific and has no differential diagnostic value.

3, bronchoalveolar lavage: the total number of cells in the recovery fluid increased, and the increase in the proportion of neutrophils is a typical change in IPF, which is helpful for diagnosis, and is still mainly used for research.

4, lung biopsy: IPF early, medium-term histological changes have certain characteristics, and the cause of interstitial lung disease includes many people with clear causes can be found, so lung biopsy is very meaningful for the diagnosis and activity evaluation of this disease, the first choice The fiberoptic bronchoscope is used as the TBLB, but the specimen is small, and it is difficult to diagnose the fashion. If necessary, the thoracotomy should be performed.

(II) Establishment of diagnosis: According to the typical clinical manifestations and the above examinations, IPF diagnosis can be established. The core problem is to exclude other interstitial lung diseases including those whose causes are unknown or unknown, and esthetic or cryptogenic are used. To indicate that the cause is unknown, but not all diseases with unexplained and pulmonary fibrosis are IPF, such as sarcoidosis, IPF is a specific disease as a whole, although it may not be a homogeneous disease, so the lungs Biopsy is necessary for the diagnosis of IPF, but in patients who are unable to receive (resistance) traumatic examination, as long as there is evidence to exclude other interstitial lung disease, it is acceptable to establish a clinical diagnosis of IPF.

(3) Activity judgment: Although there are many studies at present, there are no definite indications. Except for the histological evaluation of lung biopsy, it is considered that 67Ga scan, lung epithelial permeability measurement, bronchoalveolar lavage fluid cell number, especially lymph The number of cells and the determination of the medium have important reference value for estimating the activity of the lesion. Although the clinical manifestations, X-ray and CT signs, lung function changes and activity are not completely parallel, but the length of the disease, the degree of fibrosis and the presence or absence of honeycomb lung, lung Functional impairment, etc., is still helpful in estimating activity.

Differential diagnosis

In collagen vascular diseases (such as rheumatoid arthritis, systemic lupus erythematosus, progressive systemic sclerosis and diabetes), pneumoconiosis (such as asbestosis), radiation damage and certain drug-induced lung diseases (such as nitrofurantoin) may occur The same type of interstitial inflammation and fibrosis. However, in the above cases, this type of lesion cannot be called because it is limited to idiopathic damage and has nothing to do with other disease damage.

Need to be identified include desquamative interstitial pneumonia, respiratory bronchiol-related interstitial lung disease, inability to classify or non-specific chronic interstitial pneumonia, idiopathic obstructive bronchiolitis with organizing pneumonia , allergic pneumonia and pulmonary eosinophilic granuloma.

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