Interstitial pneumonia is an inflammation of the lung tissue that mainly affects the alveolar walls, endothelium, capillaries and fibrous tissues of the lung parenchyma. This term denotes a whole group of inflammatory processes of the interstitial tissue of the lungs of unknown origin. It is diagnosed in patients of different ages and sex: both an adult and a child can get sick. Often the outcome of the disease is pulmonary fibrosis. The most characteristic manifestations of pathology are progressive shortness of breath and deterioration of respiratory function.

Causes of the disease

The mechanisms of the origin of this disease have not been precisely established by researchers, therefore it is called idiopathic interstitial pneumonia. It is believed that the disease can begin due to a disorder of immunological self-regulation, and the impetus for its development is the appearance of an antigen, to which the immune system reacts with active production of antibodies.

The provoking factors for the development of this severe pathology can be:

• infectious agents – cytomegaloviruses, herpes viruses, viruses that provoke respiratory infections, some types of bacteria (mycoplasma, chlamydia, legionella, parasitic microorganisms: rickettsia, pneumocystis);
• inhalation of some types of dust particles;
• long-term smoking (the disease can also develop in those who got rid of this bad habit);
• immunodeficiency conditions, such as HIV and AIDS, especially in early childhood;
• the presence of some autoimmune pathologies, for example, Sjogren’s disease (connective tissues are affected with the involvement of the external secretion glands in the pathological process);
• some rheumatic diseases involving connective tissue damage;
• drug treatment with certain drugs (antiarrhythmic and antirheumatic).

Classification

Interstitial pneumonia can occur in various forms; this is a whole group of inflammatory processes, united by a common name. Depending on the nature of the lesion, focal and diffuse interstitial pneumonia are distinguished, the pathological process can occur in a separate segment, but more often the entire lobe or the whole lung is involved. The classification is carried out depending on the characteristics of the pathogenesis, clinical course and ongoing morphological changes. On these grounds, the following forms of pathology are distinguished:

1. Common (idiopathic), also called idiopathic pulmonary fibrosis. It proceeds most often chronically, with scarring of the interstitial tissue of the lungs, various changes in the structure of the organ. It is quite rare, mainly in elderly people.
2. Nonspecific – occurs in a subacute or chronic form, characterized by a uniform inflammatory process of interstitial tissues and fibrosis.
3. Acute is the most dangerous form, which is characterized by a high percentage of deaths. It has, as a rule, a sudden acute onset, the walls of the alveoli swell, exudate forms in them, and a fibrotic process develops.
4. Desquamative – proceeds in a subacute form, characterized by homogeneous inflammatory interstitial tissues of the lungs.
5. Cryptogenic – occurs in an acute, less often in a subacute form. Exudate forms in the alveoli, granulations appear in the bronchioles, while the pulmonary architectonics does not change.
6. Lymphoid (characterized by lymphocytic infiltration of the interstitial tissue of the lungs, extensive lymphadenitis, occurs in most cases chronically).
7. Respiratory bronchiolitis is a subacute course. Bronchioles and small bronchi are mainly affected, there is an unexpressed inflammatory process, sometimes fibrosis.

Symptoms

All forms of the disease are accompanied by a number of common symptoms. Among them:

• cough (dry, unproductive);
• shortness of breath (at the initial stages of the development of pathology occurs with physical exertion, with progression – it manifests itself even in a calm state);
• difficulty breathing, inability to fully inhale, feeling of lack of air;
• pain in the affected area, sometimes very intense, with a tendency to intensify when trying to breathe in deeply;
• manifestations of bronchial obstruction (most often accompany the desquamative form of the disease);
• febrile phenomena (characteristic of cryptogenic, nonspecific and lymphoid forms);
• sleep disorders;
• high fatigue at light loads;
• loss of appetite, weight loss.

The acute form is characterized by a sudden onset and rapid development, symptoms of respiratory failure rapidly increase, more than 50% of patients die. Idiopathic pulmonary fibrosis, on the other hand, begins imperceptibly, the symptoms increase rather slowly. When the pathological process begins to progress, the patient has respiratory dysfunctions, pulmonary hypertension.

Diagnostics

In the diagnosis of interstitial pneumonia, various methods are used, making a diagnosis is a rather difficult task. First, the doctor examines the patient, examines his complaints and anamnestic data.

During auscultation, soft squeaks are heard (at the initial stages of the development of the disease – mainly at the roots of the lungs, at the expanded stage – in all segments and lobes, including the apex), hard breathing, wheezing of a different nature. Percussion sound in the affected area is shorter than normal.

To make a diagnosis, the following types of examination are prescribed:

• radiography;
• respiratory function tests (plethysmography, spirography);
• high resolution computed tomography.

In the case when the data of these studies are insufficient, fibrobronchoscopy, lung biopsy can be performed.

On the roentgenogram and HRCT images, one or more foci of tissue compaction are visible, a thickening of interlobular and intralobular interstitial tissues, a decrease in the transparency of the lung parenchyma (like ground glass, mainly observed in the lower lobes of the lungs). Also, on X-ray and HRCT images, you can see the presence of segmental enlargements of the lumen of the bronchi, called bronchiectasis.

High-resolution computed tomography is the most informative research method for this disease. With its help, it is possible to establish the prevalence of the pathological process, to determine the stage and degree of intensity of the progression of fibrosis.

Differentiate pathology from bacterial pneumonia, tuberculous lesions, and other interstitial lung diseases.

Treatment

If the disease is diagnosed and treated in a timely manner, then the prospects for the patient are favorable. The most dangerous is the acute form of pathology, characterized by a rapid deterioration in respiratory function. The patient needs oxygen therapy and breathing support with mechanical ventilation.

With other types of the disease, long courses of corticosteroids (Prednisolone) and cytostatic drugs (Cyclophosphamide) are prescribed to reduce the intensity of the inflammatory process, immunosuppressive drugs (Azathioprine) to suppress the pathological activity of immune agents.

To prevent the progression of the fibrotic process, drugs such as D-penicillamine, colchicine can be used. If the progression of the pathology has led to a decrease in the level of oxygen in the blood, then oxygen therapy methods are used. If the patient has pulmonary hypertension, then it is necessary to prescribe drugs to relax the smooth muscles of the vascular walls.

In the most severe cases, a donor lung transplant may be required.

If the cause of the development of inflammation of the interstitial tissues was smoking, then the patient should treat pneumonia with a complete rejection of this habit. Only following all the recommendations of the attending physician will help to cure this complex and dangerous disease.

Forecast and prevention

Predictions for this pathology depend on the form in which it proceeds, as well as on how pronounced the fibrotic changes in the lung tissues are. On average, people with such a disease live for about five years, but if it proceeds in the form of idiopathic pulmonary fibrosis, complicated by sclerosis of the lung tissues and insufficiency of the function of the respiratory and cardiovascular systems, then the prospects are significantly worse, the survival rate does not exceed three years.

Acute interstitial pneumonia is a serious and dangerous disease that, even with early detection and adequate therapy, leads to death in more than half of the diagnosed cases.

With nonspecific interstitial pneumonia, it is possible to achieve an improvement in clinical indicators and stabilize the patient’s condition in 70-75% of cases. In a third of cases, the life prognosis is estimated at 10 years.

Desquamative interstitial pneumonia can be stabilized in 65% of patients, more than 90% live up to 10 years, 60% – five years. Sometimes, with the help of therapy, it is possible to achieve a stable remission.

With lymphoid and cryptogenic forms, the prognosis is usually favorable.

Prevention of interstitial lung diseases consists in quitting smoking, regularly vaccinating against influenza, pneumococcal infection, preventing bacterial infections, eliminating the influence of harmful and dangerous factors.