Interstitial pneumonia is a progressive inflammatory process affecting the walls of the alveoli and the connective tissue of the parenchyma, with possible secondary intraalveolar exudation and outcome in fibrous restructuring of the pulmonary structures. The disease is accompanied by increasing shortness of breath, dry or slightly sputum cough, chest pain, subfebrility, “warm” cyanosis, cardiopulmonary insufficiency. Diagnosis includes analysis of lung x-ray and CT, respiratory tests, lung biopsies. In interstitial pneumonia, corticosteroids, cytostatics, oxygen therapy, ventilators are used.
J84.1 Other interstitial pulmonary diseases with mention of fibrosis
Interstitial (idiopathic interstitial) pneumonia is a primary acute or chronic inflammation of the interstitial lung tissue of unclear etiology, characterized by its fibroproliferative changes and a decrease in respiratory function. The clinical and pathological classification identifies idiopathic interstitial pneumonia as a separate group of interstitial lung diseases (ILD), the exact prevalence of which is difficult to assess due to the rare establishment of a correct diagnosis.
Disease occupies a special place among the many problems of pulmonology, because it is characterized by a long severe course, often an unfavorable outcome due to the steadily progressive fibrous and sclerotic transformation of the lungs. With this disease, there is almost always a decrease in the quality of life and disability of patients.
Causes of interstitial pneumonia
The etiology of idiopathic interstitial pneumonia has not been fully studied. A violation of immunological homeostasis may be involved in the disease, and the trigger factor is a certain antigen, to which the body begins to produce antibodies. The development of this pathology can be provoked by infectious agents (mycoplasmas, chlamydia, pneumocysts, legionella, rickettsia, respiratory viruses, CMV, herpes virus) and certain types of dust.
People who smoke or have previously smoked, HIV-infected and AIDS patients (mainly children) are prone to interstitial pneumonia. The lymphoid form can be combined with autoimmune diseases (Sjogren’s syndrome), immunopathies (hypo- and hypergammaglobulinemia). Smoking is one of the main causes of desquamative pneumonia and respiratory bronchiolitis. Cryptogenic organizing pneumonia is usually idiopathic in nature, but it may be associated with collagenoses or drug therapy with amiodarone, gold preparations.
Inflammation in disease proceeds according to the type of pneumonitis (alveolitis), is most often of an immune non-infectious nature, affecting mainly the alveolar walls and extraalveolar connective tissue of the lungs, sometimes with a secondary organization of exudate inside the alveoli. Interstitial pneumonia is characterized by primary inflammation of interstitial tissue with the accumulation of immunocompetent cells in it that secrete various damaging mediators (oxidants, interleukin-1, etc.) at an early stage and fibrogenic factors that cause the development of fibroproliferative reactions at a late stage.
The group of interstitial pneumonia includes various pathomorphological forms of the disease. These include:
- common interstitial pneumonia (idiopathic pulmonary fibrosis/fibrosing alveolitis)
- is nonspecific
- acute (Hammen–Rich syndrome)
- desquamative (macrophage)
- lymphoid (lymphocytic)
- cryptogenic organizing
- respiratory bronchiolitis associated with ILD.
The lesion in interstitial pneumonia can be focal or diffuse, and in volume it can cover an entire lobe or the entire lung.
All variants of interstitial pneumonia have some pathogenetic, morphological and clinical differences, features of the course and prognosis:
- Idiopathic pulmonary fibrosis (IPF). Typical are heterogeneous violation of lung architectonics, scarring of interstitial tissue, “cellular” transformation of the lungs with many thin-walled cavities without contents and infiltration, foci of fibroblasts.
- Nonspecific interstitial pneumonia (NSIP) has a picture of homogeneous inflammatory changes in interstitial and fibrosis with a rare occurrence of fibroblastic foci. In acute interstitial pneumonia (IPR), there is a sharp edema of the alveolar walls, the formation of exudate and hyaline membranes inside the alveoli, and the frequent development of interstitial fibrosis.
- Cryptogenic organizing pneumonia (COP), or obliterating bronchiolitis with organizing pneumonia proceeds with the preservation of pulmonary architectonics, organized intraalveolar exudate and diffuse polyp-like granulations in the bronchioles.
- Desquamative interstitial pneumonia (DIP). In the desquamative form, there is a slight uniform inflammation of the interstitium of the pulmonary parenchyma with an accumulation of alveolar macrophages in the lining of the alveoli.
- Lymphoid intestinal pneumonia (LIP) is manifested by a combination of homogeneous pronounced lymphocytic infiltration of interstitium and peribronchial lymphoid follicles.
- Respiratory bronchiolitis. Bronchocentric migration of alveolar macrophages is typical with minimal signs of inflammation and fibrosis of the alveoli and interstitium.
The most common are idiopathic pulmonary fibrosis and a non-specific form of interstitial pneumonia. IPF is more typical for older men (average age 65 years), other forms of IIP are more often detected in female patients (35-55 years), and nonspecific and desquamative sometimes occur in children.
Symptoms of interstitial pneumonia
Chronic course (more than 12 months) is characteristic of IPF and LIP; subacute/chronic – NSIP; subacute (months and years) – DIP and RB; acute/subacute – COP; sudden – OIP. Clinical forms of interstitial pneumonia are accompanied by an unproductive (dry or with slight sputum) cough, difficulty breathing (feeling of “incomplete inhalation”) and increasing shortness of breath, first expressed during exercise, then at rest. There are chest pains, episodes of sudden lack of air at night. Shortness of breath limits the patient’s activity, accompanied by rapid fatigue, poor sleep, and sometimes weight loss.
Symptoms of bronchial obstruction in IPF are observed only in 4% of patients, they are much more common in the desquamative form. Patients may have “warm” cyanosis of the skin, which gradually covers the entire body. With COP, NSIP, LIP, fever is possible. Manifestations of the cryptogenic form often resemble the symptoms of bacterial pneumonia. For IPF, nonspecific, desquamative and lymphocytic interstitial pneumonia, “Hippocratic fingers” are typical.
IPF has an imperceptible beginning with a slow increase in shortness of breath and cough, general weakness, pain in muscles and joints, absence of fever and hemoptysis. The progression of this form is accompanied by weight loss (up to cachexia), the development of respiratory disorders, primary pulmonary hypertension. Severe respiratory failure with manifestations of the pulmonary heart in IPF can form over a period of 2 months to 2 years.
The symptoms of acute interstitial pneumonia (Hammen–Rich syndrome) are similar to the clinic of influenza and acute respiratory distress syndrome. There is a lightning-fast course with rapidly progressive respiratory failure and a high percentage of deaths.
Complications of interstitial pneumonia can be lung carnification with the formation of pneumosclerosis, the development of a “cellular” lung, respiratory and heart failure, and the addition of a secondary bacterial infection. The stage of the “cellular” lung in interstitial pneumonia is defined as prognostically unfavorable in terms of the occurrence of lung cancer.
Diagnosis of interstitial pneumonia is difficult, based on the results of anamnesis, physical examination, radiography and CT of the lungs, studies of FER (spirometry, bodyplethysmography); thoracoscopic or open lung biopsy.
In interstitial pneumonia, mild crepitation is detected: at an early stage, mainly in the basal segments of the lungs, at a late stage – in all pulmonary fields and in the tops of the lungs. Inspiratory crepitation of the “cellophane cod” type is typical for IPF. There is hard breathing, wet or dry small-bubbly wheezing in the lungs. With percussion, there is a slight shortening of the sound corresponding to the affected area. Instrumental diagnostics includes:
- Functional breathing tests. There is a violation of ventilation and disorders of the diffusion ability of the lungs (with IPF – restrictive type with a sharp and extremely sharp decrease in lung volumes).
- Radiography. Radiological signs of this disease may be symmetrical translucent darkening of the “frosted glass” type, mainly in the lower parts of the lungs; thickening of the interlobular and intralobular interstitium; cystic fibrotic changes, perivascular and peribronchial infiltration and traction bronchiectasis.
- High-resolution CT. It helps to clarify the prevalence of lung tissue damage, assess the stage, activity and rate of progression of the fibrous process.
- Biopsy. An important stage in the diagnosis of interstitial pneumonia is a lung biopsy with histological analysis of lung tissue biopsies.
- EchoCG. Echocardiographic symptoms of hemodynamic disorders in the small circle of blood circulation are noted only with sufficiently high indicators of the area of fibrous changes in the lungs.
Differential diagnosis of interstitial pneumonia is performed with bacterial pneumonia, tuberculosis, and other ILD. Therapeutic and diagnostic measures for interstitial pneumonia involve the interaction of a pulmonologist, a thoracic surgeon, a radiologist, a pathologist.
Interstitial pneumonia treatment
Early diagnosis of interstitial pneumonia has a positive effect on the effectiveness of treatment and prognosis. In the case of acute interstitial pneumonia, respiratory function is maintained with the help of oxygen therapy and artificial lung ventilation. Treatment of other forms is based on the use of glucocorticosteroids (GCS) and cytostatics capable of having a pronounced anti-inflammatory and immunosuppressive effect.
With NSIP, COP, RB-IBL, DIP and LIP, high or medium doses of prednisolone are indicated for a long course, if necessary, the addition of cytostatic drugs. Quitting smoking is a prerequisite for the resolution of desquamative interstitial pneumonia and respiratory bronchiolitis associated with ILD. In IPF, GCS-monotherapy and more preferred combinations with azathioprine or cyclophosphamide are used for at least 6 months with careful monitoring of the patient’s condition.
Antifibrotic drugs (D-penicillamine, colchicine, interferon γ-1b) are used as additional ones. With the development of hypoxemia, oxygen therapy is recommended, with pulmonary hypertension – vasodilators. Effective use of drugs that affect the functional activity of the endothelium – prostaglandins, antiplatelet agents, endothelin-1 inhibitors, antioxidants. In the formation of a “cellular lung”, the only method of treating interstitial pneumonia is lung transplantation.
The outcome of interstitial pneumonia depends on the form of the disease and the severity of pulmonary fibrosis. The survival rate of patients on average is 5-6 years, with IPF with the development of pneumosclerosis and cardiopulmonary insufficiency, life expectancy does not exceed 3 years. Acute interstitial pneumonia, even with timely treatment, has very high mortality rates – up to 50-70%.
Clinical improvement and stabilization of the patient’s condition as a result of treatment of nonspecific for, occurs in about 75% of cases; about 35% of patients have a 10-year survival rate. In the desquamative form, improvement / stabilization is observed in 2/3 of cases, and 5- and 10-year survival reaches 93 and 69%, complete remission is possible.
Most cases of lymphocytic interstitial and cryptogenic organizing pneumonia have a favorable prognosis. RB-ILD is often resolved upon cessation of smoking, in some cases there is a persistent progression with relapses. IPF patients are regularly vaccinated against influenza and pneumococcal infection.
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