Idiopathic fibrosing alveolitis - Overview of information

Interstitial lung diseases are a large group of diseases of various etiologies, characterized by inflammatory lesions of the alveolar walls (alveolitis) and the interstitial tissue surrounding them. Currently, this group includes more than 130 diseases; however, infectious lung diseases of known etiology and malignant tumors (for example, lymphogenous carcinomatosis), which may cause similar clinical symptoms, are not classified as interstitial lung diseases.

Depending on the etiology, a distinction is made between interstitial lung diseases of known and unknown etiology, and within each group, two subgroups are distinguished (the presence or absence of granulomas in the interstitial tissue).

B. M. Korenev, E. A. Kogan and E. N. Popova (1996) propose classifying interstitial lung diseases taking into account the characteristics of the morphological picture of damage to the pulmonary interstitium. Interstitial lung diseases have a number of common characteristic features:

• progressive clinical course;
• progressive restrictive respiratory failure;
• X-ray picture of diffuse damage to lung tissue in the form of increased and deformed pulmonary pattern and small or medium focal dissemination;
• the leading role of immune mechanisms in the pathogenesis of most nosological forms.

Idiopathic fibrosing alveolitis is a disseminated lung disease characterized by inflammation and fibrosis of the pulmonary interstitium and air spaces, disorganization of the structural and functional units of the parenchyma, leading to the development of restrictive changes in the lungs, impaired gas exchange, and progressive respiratory failure.

The disease was first described by Hamman and Rich in 1935.

Causes and pathogenesis of idiopathic fibrosing alveolitis

The causes of idiopathic fibrosing alveolitis have not been definitively established. The following possible etiologic factors are currently under discussion:

• viral infection - the so-called latent, "slow" viruses, primarily the hepatitis C virus and the human immunodeficiency virus. A possible role of adenoviruses, Epstein-Barr virus is also assumed (Egan, 1995). There is a point of view on the dual role of viruses in the development of idiopathic fibrosing alveolitis - viruses are the primary triggers for the development of lung tissue damage and, in addition, virus replication occurs in already damaged tissue, which naturally contributes to the progression of the disease. It has also been established that viruses interact with genes regulating cell growth, and thus stimulate collagen production, fibroformation. Viruses are also capable of intensifying existing chronic inflammation;
• environmental and professional factors - there is evidence of a connection between idiopathic fibrosing alveolitis and long-term professional contact with metal and wood dust, brass, lead, steel, and some types of inorganic dust - asbestos, silicate. The etiological role of aggressive etiological factors is not excluded. However, it should be emphasized that the above-mentioned professional factors cause pneumoconiosis, and in relation to idiopathic fibrosing alveolitis, they can probably be considered as trigger factors;

Idiopathic fibrosing alveolitis - Causes and pathogenesis

Symptoms of idiopathic fibrosing alveolitis

Idiopathic fibrosing alveolitis develops most often between the ages of 40 and 70, and in men it is 1.7-1.9 times more common than in women.

The most typical is a gradual, barely noticeable onset, however, in 20% of patients the disease begins acutely with an increase in body temperature and severe shortness of breath, but subsequently the body temperature normalizes or becomes subfebrile.

For idiopathic fibrosing alveolitis, the complaints of patients are extremely characteristic, a thorough analysis of which allows us to suspect this disease:

• dyspnea is the main and constant manifestation of the disease. At first, dyspnea is less pronounced, but as the disease progresses, it increases and becomes so pronounced that the patient cannot walk, take care of himself or even talk. The more severe and prolonged the disease, the more pronounced the dyspnea. Patients note the constant nature of dyspnea, the absence of attacks of suffocation, but often emphasize the inability to take a deep breath. Due to progressive dyspnea, patients gradually reduce their activity and prefer a passive lifestyle;

Idiopathic fibrosing alveolitis - Symptoms

Diagnosis of idiopathic fibrosing alveolitis

An important marker of the activity of idiopathic fibrosing alveolitis is an increase in the level of surfactant glycoproteins A and D in the blood serum, which is due to a sharp increase in the permeability of the alveolar-capillary membrane.

With the development of decompensated pulmonary heart disease, a moderate increase in the blood levels of bilirubin, alanine aminotransferase, and gamma-glutamyl transpeptidase is possible.

Immunological blood test - characteristically a decrease in the number of T-suppressor lymphocytes and an increase in T-helpers, an increase in the general level of immunoglobulins and cryoglobulins, increased titers of rheumatoid and antinuclear factors, possible appearance of antipulmonary antibodies, circulating immune complexes. The indicated changes reflect the intensity of autoimmune processes and inflammation of the pulmonary interstitium.

Idiopathic fibrosing alveolitis - Diagnosis

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