Interstitial pneumonia

Introduction to interstitial pneumonia Interstitial lung disease (ILD), also known as interstitial lung disease, diffuse lung disease, etc., as a disease name, only a history of more than 10 years, as its name suggests it is a lung interstitial lesion. Interstitial pneumonia is not a single disease, but a general term for a large class of diseases. There are about a hundred kinds of diseases. A small number of causes are known, such as pneumoconiosis, drug pneumonia, radiation pneumonitis, etc.; but there are quite a few causes. Unknown, such as idiopathic pulmonary fibrosis, sarcoidosis. Although interstitial pneumonia is called "pneumonia", it is mainly not caused by infection by microorganisms such as bacteria and viruses. basic knowledge The proportion of illness: 0.001% Susceptible people: no special people Mode of infection: non-infectious Complications: pulmonary fibrosis, respiratory failure

Cause of interstitial pneumonia

Inhalation of inorganic dust (15%):

Silica, asbestos, talc, antimony, bismuth, coal, aluminum, tin, iron.

Inhalation of organic dust (15%):

Mold grass dust, sugar cane dust, mushroom lung, pigeon disease, cotton dust, synthetic fiber, bakelite radiation damage.

Microbial infection (10%):

Virus, bacteria, fungi, Pneumocystis carinii, parasites.

Drug factors (10%):

Cytotoxic chemotherapy drugs, mesamine, cyclophosphamide.

Disease factors (15%):

Cancerous lymphangitis, pulmonary edema, etc.

Inhalation gas (15%):

Oxygen, sulfur dioxide, chlorine, nitrogen oxides, soot, lipids, mercury vapor

Unknown cause

Idiopathic pulmonary interstitial fibrosis (also known as cryptogenic fibrotic alveolitis, idiopathic interstitial pneumonia), acute interstitial pneumonia; desquamative interstitial pneumonia; collagen vascular disease: systemic Lupus erythematosus, rheumatoid arthritis, ankylosing spondylitis, polymyositis-dermatomyositis, Sjogren's syndrome; sarcoidosis; histiocytosis; pulmonary hemorrhagic-nephritis syndrome; idiopathic pulmonary hemorrhage Xanthinosis; Wegener granuloma; chronic eosinophilic pneumonia; alveolar proteinosis; hereditary pulmonary fibrosis; tuberous sclerosis, neurofibromatosis; pulmonary vascular interstitial lung disease; primary pulmonary hypertension Diffuse amyloidosis; obliterative bronchiolitis and organizing pneumonia.

It is known that the etiology category accounts for about 35% of all ILD. Among them, occupational exposure is the common cause of the disease, among which inorganic dust is the most common cause, and the number of organic dusts is increasing, and organic dust is also caused. Allergic alveolitis, often because of a history of allergies, when inhaled allogeneic protein or polysaccharides, the cause of unknown ILD accounted for 2 / 3 of all cases, including idiopathic pulmonary fibrosis, sarcoidosis and collagen Vascular disease is most common in the lungs, histiocytosis X, pulmonary-renal syndrome and pulmonary vasculitis, and idiopathic hemosiderin.

Pathogenesis

The exact pathogenesis of ILD has not yet been fully elucidated, but ILD changes from different causes start from alveolitis, and the propensity to cause pulmonary fibrosis during development and repair has something in common. Activated macrophages have the function of regulating lymphocytes. And secretory inflammatory mediators such as complement components, prostaglandins, collagenase, elastase, neutral protease, plasmin activator, beta glucuronidase, angiogenic factors, fibroblast growth factor and neutrophils The role of chemokines, activated T lymphocytes can secrete lymphokines, such as macrophage migration inhibitory factor, leukocyte inhibitory factor, monocyte chemotactic factor and macrophage activating factor, B lymphocytes can secrete IgG, IgA And IgM, etc., neutrophils can secrete collagenase, elastase, neutral protease (cathepsin G), acid protease (cathepsin D), beta glucuronidase and inflammatory pathways that activate various body fluids.

Pathological classification

(1) Classification by pathological changes:

1 non-inflammatory non-neoplastic diseases: such as sarcoidosis, exogenous granulomatous alveolitis.

2 granulomatous interstitial lung disease: such as chronic interstitial pulmonary edema, alveolar proteinosis, primary pulmonary hemosiderosis, uremia and so on.

3 lung-specific inflammation: such as common interstitial pneumonia, obliterative bronchiolitis and organizing pneumonia (BOOP), exogenous irritating smog, fluid and other toxic stimulating chronic interstitial pneumonia, acute respiratory distress Syndrome (ARDS), idiopathic pulmonary fibrosis and pulmonary vasculitis.

4 inorganic dust inhalation occupational disease.

5 hyperplasia and neoplastic lesions: such as primary bronchioloalveolar carcinoma induced pulmonary interstitial lesions, diffuse Hodgkin's lymphoma.

6 pulmonary interstitial fibrosis and honeycomb lung (end lung).

(2) Classification according to the type of cells aggregated in the alveolar structure:

1 macrophage-lymphocyte-neutrophil type: referred to as neutrophilic alveolitis, macrophages still account for the majority, but neutrophils increase, and long-term accumulation in the alveolar structure, the most typical of this type The characteristics of this type of lesion are: idiopathic pulmonary fibrosis (cryptogenic fibrosis alveolitis), familial pulmonary fibrosis, chronic interstitial pulmonary fibrosis associated with collagen vascular disease, tissue Cell hyperplasia X and asbestosis lungs.

2 macrophage lymphocyte type: abbreviated lymphocytic alveolitis, macrophages and lymphocytes increased, but lymphocytes increased more than macrophages, neutrophils did not increase, sarcoidosis, allergic Pneumonia and sputum poisoning, etc., belong to this type.

Pulmonary parenchymal cells are directly affected by certain pathogenic factors, or acute alveolitis occurs through the indirect effects of inflammation and immune cell system. In the stage of alveolitis, such as removal of the cause or treatment, the lesion can be reversed; when acute alveolitis Turning to chronic, neutrophils secrete collagenase and elastase, destroy type I collagen and alveolar wall, affecting the reversibility of lesions, such as the further development of lesions, disordered collagen fibers in the interstitial, microscopic examination of a large number of fibrous tissue proliferation, The alveolar septal destruction, the formation of cystic fibrosis, the destruction of the alveolar wall is irreversible; the lesions further develop into complete damage to the alveolar structure, forming a wide range of cystic fibrosis.

2. Staging of interstitial lung disease:

Stage I: Impaired lung parenchymal cells, acute alveolitis, inflammatory and immune effector cells proliferate, recruit and activate.

In the bronchoalveolar lavage fluid of idiopathic pulmonary fibrosis, it is confirmed that there is an immune complex that stimulates macrophages to secrete neutrophil chemotactic factors, allowing neutrophils to accumulate in the alveolar structure, activated macrophages. Cells and neutrophils can secrete collagenase, and bronchoalveolar lavage is followed up for 8 to 24 months. Collagenase activity persists. Activated collagenase can destroy interstitial collagen of alveolar structure (in acute pneumonia such as pneumococcal pneumonia) The presence of neutrophils in the alveolar structure is very short, so it does not cause progressive and permanent damage to the interstitial connective tissue.) Isolation of idiopathic fibrosis and sarcoidosis bronchoalveolar lavage fluid Macrophages, cultured in RPMI-1640-free medium, produced fibronectin at a rate 20-fold and 10-fold faster than normal macrophages, respectively. Fibronectin has a chemotactic effect on lung fibroblasts. In the formation of interstitial fibrosis plays an important role, sarcoidosis T lymphocytes can secrete lymphoapoptin, causing granuloma formation, in the stage I, the lung parenchymal damage is not obvious, if stimulated Su is eliminated, the lesion can be restored.

Stage II: alveolitis evolves to be chronic, and the non-cellular and cellular components of the alveoli are progressively damaged, causing changes in the number, type, location, and/or differentiation properties of the lung parenchymal cells, and damage to type I epithelial cells. Type II epithelial cell hyperplasia repair, from stage I to stage II, either fast or slow, the elderly can reach several years, subject to various factors such as exposure period, lung defense mechanism effectiveness, damage range, basement membrane integrity and The susceptibility of the individual affects the destruction of the alveolar structure and becomes irreversible.

Stage III: It is characterized by interstitial collagen disorder. Microscopic examination reveals a large amount of fibrous tissue hyperplasia. Fibroplasia is not caused solely by fibroblast activation, but by various composite factors such as collagen synthesis and various types of cell abnormalities. Collagen The tissue is broken, the alveolar septum is destroyed, and cystic changes are formed. By the third stage, most of the alveolar structure is damaged and significantly disordered, and demobilization is impossible.

Stage IV: In the advanced stage of the disease, the alveolar structure is completely damaged, and replaced with a diffuse non-functional cystic change, and the basic structure and characteristics of various types of interstitial fibrosis cannot be identified.

The boundaries of the above periods are difficult to separate and overlap each other.

Interstitial pneumonia prevention

ILD for which the cause is unknown is not yet preventable.

However, the risk of developing idiopathic pulmonary fibrosis is increased in smokers, and the risk increases with the increase in smokers. The cause of prevention of ILD prevention should be for all types of personnel in a large dust working environment, long-term exposure to irritating gases such as chlorine, ammonia, carbon dioxide, formaldehyde and various types of acid mist, radiation-damaged and bird-raising The crowds and other key monitoring, regular lung function measurement, blood gas analysis and routine X-ray examination, timely detection of disease, timely diagnosis and treatment. In addition, inhalation of various microorganisms, microparticles, heterologous protein allergens, and harmful irritating gases in the air can also cause lung damage. Through clinical observation, the pathogenesis of ILD is sometimes very slow. Clinically, patients who have been exposed to dust or poison in youth and have obvious symptoms in old age are often encountered. For these elderly patients, due to low immune function, nutritional status Poor and the existence of basic diseases such as heart, lung and kidney are very difficult to treat and the mortality rate is very high. The physical activity of the elderly may mask the symptoms of dyspnea and shortness of breath caused by this disease. Therefore, the high-risk group of the disease should take the family as the unit, take the health care function as the community, and carry out regular health education and health consultation.

Interstitial pneumonia Complications pulmonary fibrosis respiratory failure

Mainly complicated by pulmonary fibrosis, respiratory failure and so on.

Symptoms of interstitial pneumonia Common symptoms Straight sputum dry cough labor dyspnea clubbing (toe) Inhalation burst sound of both lungs Fatigue purple

Have difficulty breathing, dry cough. Since then, it has been induced and aggravated by colds and acute respiratory infections, and it is progressively aggravated. Gradually there is increased breathing but no wheezing, irritating cough or cough, and a few have fever, hemoptysis or chest pain. After severe, the movement is asthmatic, flustered with sweat, body weakness, weight loss, lip purpura and clubbing (toe). A wet rales can be heard in the lower lungs during a physical examination. In the case of concurrent pulmonary heart disease, there is a second sound of the pulmonary artery, jugular vein, hepatomegaly and lower extremity edema.

The main symptom of interstitial pneumonia in the early stage is cough, which is not easy to detect the cause, so it is easy to be delayed, and the disease can only be stable and cannot be cured. Chinese medicine conditioning has a certain effect. In the late stage, fibrosis of the lungs occurred and cracks appeared. This leads to difficulty breathing. The fibrotic process is irreversible and is basically ineffective in the late stage. The cause of the disease is not known internationally, and the exact treatment is not known.

Currently, ILD/DPLD is divided into four categories internationally:

1 known cause of DPLD

Such as drug-induced, occupational or environmentally harmful substances induced (, asbestos) DPLD or pulmonary vascular disease, etc.;

2 idiopathic interstitial pneumonia

Idiopathic interstitial pneumonia (IIP), including seven clinical pathological types: idiopathic pulmonary fibrosis (IPF)/interstitial pneumonia (UIP), non-specific interstitial pneumonia (NSIP) ), cryptogenic organizing pneumonia (COP) / organizing pneumonia (OP), acute interstitial pneumonia (AIP) / diffuse alveolar damage (DAD), respiratory bronchiolitis with interstitial lung disease ( RB-ILD)/breathing bronchiolitis (RB), desquamative interstitial pneumonia (DIP), lymphocytic interstitial lung (LIP);

3 granulomatous DPLD

Such as sarcoidosis, exogenous allergic alveolitis, Wegener granulomatosis, etc.;

4 other rare DPLD

Such as alveolar proteinosis, pulmonary hemorrhagic-nephritis syndrome, pulmonary lymphangioleiomyoma, Langerhans cell histiocytosis, chronic eosinophilic pneumonia, idiopathic pulmonary hemosiderosis, etc. .

Interstitial pneumonia

blood test

Inflammatory and immune cell abnormalities in the alveolar structure of interstitial pneumonia are not associated with other extrapulmonary lesions. In many patients, erythrocyte sedimentation rate, or elevated blood immunoglobulin, is not closely related to pulmonary fibrosis. In some patients, immune complexes can be found in the serum and are spilled from the lungs. Some patients have positive rheumatoid factor and anti-nuclear antibodies, and some patients have anti-lung collagen antibodies in serum. Arterial blood gas analysis: due to decreased tidal volume, increased respiratory rate, shallow breathing, insufficient alveolar ventilation, resulting in decreased ventilation/blood flow, hypoxemia, but normal arterial carbon dioxide partial pressure. The blood oxygen partial pressure decreased significantly after exercise. Bronchoalveolar perfusion examination: Bronchoalveolar lavage fluid was obtained by inserting the left lung lingual lobe or the right middle lobe with fiberoptic bronchoscopy and irrigating with normal saline. The lavage fluid was assayed for cytological and non-cellular components. This method has the following advantages: 1 The cytological examination of the lavage fluid can truly reflect the type and number of inflammatory and effector cells in the alveolar structure of alveolitis. 2 diagnosis and differential diagnosis of various interstitial lung diseases. The total number of cells in non-smoker lavage fluid is (0.2-0.5)×10 ⁴ /ml, among which alveolar macrophages account for 85%-90%, lymphocytes account for about 10%, and neutrophils and eosinophils only account for 10%. Below 1%, the total number of cells is increased by the increase of alveolar macrophages, and the changes of cell types are diagnostic in ILD. Lymphocytes showed a significant increase in allergic alveolitis, sarcoidosis, and chronic silicosis. Increased lymphocytes are also seen in collagen disease with pulmonary fibrosis. Increased neutrophils in bacterial pneumonia, airway infection, and ARDS. Increased lymphocytes and granulocytes may occur in bronchiolitis obliterans with organizing pneumonia. T lymphocytes in bronchoalveolar lavage fluid account for 70% to 80% of T cells, and B cells account for 10% to 20%, while sarcoidosis, allergic alveolitis, and chronic silicosis in TLD increase T cells. I have always wanted to explain the activity and prognosis of ILD with the degree of activation of labeled T cell subsets or T cells and B cells. Only the increase in the number of T cells and the number of activated T cells in sarcoidosis is related to the progression of the disease. In addition, the increase of B cells activated during idiopathic pulmonary interstitial fibrosis suggests a progression of the disease, and lymphocytosis has a better effect on hormone therapy and a better prognosis.

Chest X-ray

One of the common methods of diagnosing interstitial pneumonia. Early alveolitis shows blurred shadows in both lower lung fields, and the density is increased like frosted glass. Because the early clinical symptoms are not obvious, the patient rarely sees the doctor, is easily ignored, the disease progresses further, and there are reticular shadows or even reticular nodules in the lung field. Shadows, nodules ranging from 1 to 5 mm in size. In the late stage, there are cystic changes of different sizes, which are honeycomb lungs, lung volume shrinks, diaphragmatic uplift, interlobular fissure shift, and the diagnosis is easier in the late stage, but the significance of early diagnosis has been lost. About 30% of patients have interstitial pulmonary fibrosis confirmed by lung biopsy, but chest X-ray is normal, so X-ray is not sensitive enough to alveolitis and lacks specificity. Pulmonary CT or high-resolution CT: The lung tissue and interstitial are more detailed to show their morphological changes, which is valuable for early pulmonary fibrosis and the establishment of honeycomb lung. Features of CT images include nodule shadow, bronchial wall Four images, such as regular shadow, linear shadow and lung field concentration, can appear in the center of the leaflet, around the pleura, around the vein, in the irregular shadow of the venule and bronchial vessel wall. Similarly, bronchial wall irregularities occur in the center of the lobule, around the bronchial artery and veins and venules. High-resolution CT imaging is superior to common X-ray chest in the diagnosis of interstitial lung disease, and is valuable for early pulmonary fibrosis and the establishment of honeycomb lung. In particular, CT images have unique diagnostic value in determining ILD, which is often dominated by peripheral lesions.

Pulmonary function tests

This test is only a functional diagnosis, not a pathological diagnosis. In the early stage, the pulmonary function test can be completely normal, and the abnormality of the pulmonary function test may occur when the disease progresses. The most significant changes in lung function in ILD are abnormalities in ventilation function and a decrease in gas exchange function. Ventilation function is mainly based on restrictive ventilation disorder, decreased lung capacity, and the amount of residual gas decreases as the disease progresses, and the total lung volume also decreases. The ratio of 1st time lung capacity (FEV1.0) to forced vital capacity (FVC) was significantly higher than that of 1st, and if it reached 90%, the diagnosis of ILD was supported. Early stage of ILD may have small airway dysfunction, and both V50 and V25 decrease the V50 and V25 after ILD forms fibrosis. Gas exchange dysfunction can also occur in the early stages of ILD. For example, the diffusion function (DLCO) is reduced at an early stage. Once the interstitial changes are found on the chest X-ray, DLCO has been reduced by less than 50%. The correlation between lung function changes and lung lesions was extremely poor in patients with mild lesions, and the correlation was better in patients with severe disease. In cases of severe lung damage, the lung lesions must be severe. In the various tests of lung function, the volume-pressure curve test and changes in arterial oxygen in exercise are most sensitive to the severity of pulmonary fibrosis. Pulmonary function tests are very useful for early diagnosis and prognosis of ILD, especially for dynamic observation of VC, FEV1.0, DLCO and other indicators. As to whether pulmonary function tests can judge the efficacy of hormones or immunosuppressive agents in the treatment of ILD, there are different opinions. It is not enough to evaluate the efficacy only by changes in lung function.

Lung biopsy

Lung biopsy is the best procedure for diagnosing ILD. Lung biopsy is performed when medical history, X-ray film, pulmonary function tests, and bronchoalveolar lavage, as well as biochemical, infectious disease, and other tests cannot be inferred. Lung biopsy is divided into two types: 1 using fiberoptic bronchoscopy for lung biopsy. Its advantages are simple operation and high safety. It can be used as a routine examination and easy to review. Scholars believe that the lung tissue taken by the fiberoptic bronchoscope is too small, and it is difficult to see the whole pathological structure (<2mm). Moreover, the rate of misdiagnosis and missed diagnosis is high, and 5 to 6 pieces of lung tissue can be taken to increase the positive rate. 2 Scratch chest lung biopsy: cut the lung tissue 2cm × 2cm, can fully observe the type and extent of alveolitis. Although this method is a means of invasive examination, it is undoubtedly necessary to open a chest biopsy in terms of establishing a diagnosis and avoiding unnecessary types of examinations and unintended treatments. Foreign scholars have reported that 90% of cases that cannot be clearly diagnosed by fiberoptic bronchoscopy can be diagnosed by open chest biopsy, and that interstitial pneumonia and desquamative interstitial in idiopathic pulmonary fibrosis are considered. Pneumonia can only be diagnosed if it is opened by a chest biopsy. In contrast, there are very few open lung biopsy in China, which is the main reason for hindering the improvement of diagnostic level.

67Ga radionuclide scanning

67Ga does not accumulate in normal tissues and organs, but accumulates in chronic inflammatory tissues with high sensitivity but low specificity. The 67Ga index, which is the percentage of total lung area where 67Ga accumulates in the lungs. >50U means positive. 70% of idiopathic pulmonary fibrosis 67Ga index >50U.

Epidemiology

The disease is mostly scattered, found in all age groups, more than 40 to 70 years old, the incidence of ILD in the United States is 20/100,000 to 40/100,000, the United States Center for Disease Control statistics, post-inflammatory fibrosis (collagen vascular disease, The number of deaths from radiation pneumonitis and asbestosis lungs rose from 48.6/100,000 (1979) to 50.9/100,000 (1991), and from 21.4/100,000 to 27.2/100,000, about the increase in ILD reports. The rate is also growing. The incidence of idiopathic pulmonary interstitial fibrosis is unknown. Between 1990 and 1994, it was reported that the incidence rate was 3/100,000 to 6/100,000. More men than women in this disease, the survey data of New Mexico in 1994 showed that the incidence of idiopathic pulmonary fibrosis was 20.2/100,000 for men and 13.2/100,000 for women, mostly middle-aged, usually 40-70 years old. The average age at diagnosis was 66 years and the incidence increased with age. The incidence rate is 2.7/100,000 in the 35-44 age group; the incidence rate increases to 175/100,000 in the 75-year-old. There is no obvious geographical distribution difference, and there is no obvious ethnic tendency, but the mortality rate seems to be higher than that of black people, and the reason is unclear. Mortality increases with age. ILD for which the cause is unknown is not yet preventable. However, the risk of developing idiopathic pulmonary fibrosis is increased in smokers, and the risk increases with the increase in smokers. The cause of prevention of ILD prevention should be for all types of personnel in a large dust working environment, long-term exposure to irritating gases such as chlorine, ammonia, carbon dioxide, formaldehyde and various types of acid mist, radiation-damaged and bird-raising The crowds and other key monitoring, regular lung function measurement, blood gas analysis and routine X-ray examination, timely detection of disease, timely diagnosis and treatment. In addition, inhalation of various microorganisms, microparticles, heterologous protein allergens, and harmful irritating gases in the air can also cause lung damage.

Diagnosis and diagnosis of interstitial pneumonia

Diagnostic criteria

1. History and occupational history

About 1/3 of the causes of ILD are clear. Among them, exposure to exogenous antigens accounts for a considerable proportion of occupational environment. Therefore, medical history and occupational history may provide important diagnostic clues. Detailed information on past history such as occupation, hobbies, and medications should be collected.

2, clinical manifestations

Mostly insidious onset, progressive progressive increase in labor dyspnea is the most common symptom, usually accompanied by dry cough, fatigue. The main signs are shallow breathing, bursting sounds with double lower lungs, cyanotic purpura and clubbing (toe), pulmonary hypertension and right ventricular hypertrophy in the late stage, often due to respiratory failure or (and) heart failure.

3, chest imaging examination

The early abnormal signs of chest radiographs have ground-glass shadows and increased lung texture, which are often overlooked. Further development of the lesions, there may be a wide range of mesh shadows, reticular nodules, nodular shadows, etc., late in the cellular lung-like changes, lesions often involving both lung fields.

Differential diagnosis

Interstitial pneumonia is more difficult to diagnose than alveolar inflammation, lung texture weight gain, edge blur, reticular and point shadows and emphysema coexist as its main performance. The X-ray findings of interstitial pneumonia are similar to those of other interrelated pulmonary interstitial lesions (collagen disease, pneumoconiosis, histiocytosis X, sarcoidosis, bronchiolitis), and should be identified.

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