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Chronic Diffuse Lung Diseases

*Morbi pulchri diffusi chronici*

For medical students2 min readUpdated 2026-10-10

Chronic diffuse lung diseases represent the most prevalent pathology of the bronchopulmonary system, characterized by a steady increase in incidence and involvement of the respiratory or conducting airways. Chronic bronchitis predominates within the structure of this pathology.

Leading PathologyThe most common disease of the bronchopulmonary system

Patient GrowthThe number of patients doubles every 10–12 years

Chronic BronchitisAccounts for 65–90% of the incidence structure

Functional TypesDivided into obstructive, restrictive, and mixed

Epidemiology and Incidence Structure

Chronic diffuse lung diseases rank first in prevalence among all chronic bronchopulmonary pathologies. Statistics show a steady upward trend in the number of cases:

In urban areas, the annual growth rate is 6–7%.
In rural areas, this figure is 2–3%.

The total number of patients with this pathology doubles every 10–12 years. The largest share (from 65 to 90%) in the incidence structure belongs to chronic bronchitis. There is also an increase in cases of bronchial asthma, which is accompanied by epidemic flare-ups.

Etiology and Pathogenesis

The development of the pathological process is closely linked to a complex of adverse factors:

Environmental factors: atmospheric pollutant emissions.
Smoking as a potent damaging agent.
Occupational hazards: continuous contact with organic and mineral dusts, toxic gases, and isocyanates.
Infections: previous acute respiratory infections, especially of viral etiology.
Immune status: individual state of the body's defense mechanisms.
Genetic predisposition: the role of hereditary factors has been proven, in particular the PiZZ and PiSS phenotypes, which cause alpha-1 antitrypsin deficiency.

The morphogenesis of the pathology develops strictly along one of three possible pathways.

Classification of Lung Lesions

Taking into account functional features and the nature of morphological changes in the conducting or respiratory divisions, all diseases are subdivided into three main groups:

Obstructive — characterized by impaired airway patency.
Restrictive — characterized by limited lung expansion and reduced lung volume.
Mixed — combining features of both obstruction and restriction.

Note: A mixed type of lesion characteristically develops in the late stages of virtually all chronic diffuse lung diseases.

Mnemonic

Doubling every 10–12 years, and bronchitis accounts to 65–90%: remember the rule '10 years to double and nearly 90% for bronchitis'.

Frequently asked questions

Through what three pathways does the morphogenesis of chronic diffuse lung diseases occur?

The morphogenesis of chronic diffuse lung diseases is implemented through three main mechanisms. These include:

Bronchitogenic — based on impaired bronchial drainage function and bronchial patency.
Pneumoniogenic — develops as a consequence of acute pneumonia and its complications.
Pneumonitogenic — based on primary inflammation of the interstitium.

All three mechanisms ultimately lead to the development of pulmonary sclerosis, secondary pulmonary hypertension, and cor pulmonale.

Which nosologies belong to the group of chronic obstructive pulmonary diseases?

The group of chronic obstructive pulmonary diseases includes five main nosologies. These are:

Chronic obstructive bronchitis;
Bronchiectasis;
Chronic obstructive pulmonary emphysema;
Chronic bronchiolitis;
Bronchial asthma.

The development of these diseases is based on impaired bronchial drainage function (obstructio — hindrance, obstacle), which is accompanied by decreased airway patency and increased resistance to airflow.

What morphological changes in the bronchial wall are characteristic of chronic bronchitis?

Chronic bronchitis is characterized by the development of chronic inflammation within the bronchial wall. The main morphological substrates of the disease include:

Chronic inflammation of the bronchial wall;
Goblet cell hyperplasia;
Mucous gland hyperplasia — accompanied by mucus production.

The pathological process affects the entire bronchial tree, including the bronchioles, leading to the development of chronic bronchiolitis.

Which disease holds the largest share in the structure of CDLD?

Chronic bronchitis holds the largest share, accounting for 65% to 90% of cases.

How often does the total number of CDLD patients double?

The total number of patients doubles every 10–12 years.

What groups are distinguished in the functional classification of lung diseases?

Three groups are distinguished: obstructive, restrictive, and mixed (combining obstruction and restriction).

Which genetic factor predisposes to the development of this pathology?

Genetic predisposition is associated with the PiZZ and PiSS phenotypes, which cause alpha-1 antitrypsin deficiency.

Go deeper

Dynamics of incidence growth among urban and rural populations
Impact of occupational factors and pollutants on lung tissue
Role of alpha-1 antitrypsin deficiency (PiZZ, PiSS phenotypes) in pathogenesis
Three possible pathways of chronic diffuse lung disease morphogenesis
Clinical and morphological differences between obstructive and restrictive disorders in late stages