Cavernous and fibrotic cavernous pulmonary tuberculosis

With a relatively favorable course of tuberculosis, infiltration and fresh foci sometimes quickly resolve, but the cavity of decay in the lung tissue can persist, become delimited and turn into a cavern. Under conditions of specific chemotherapy, such a course of the process has become much more frequent, and cavernous tuberculosis has been isolated as a separate clinical form. A tuberculous cavern is a cavity formed in the area of tuberculous damage, delimited from the adjacent lung tissue by a three-layer wall.

After the formation of a cavity, the initial form of tuberculosis loses its typical manifestations, and the tuberculosis process, which remains active, acquires new features. An important feature of cavernous tuberculosis is the limited and reversible nature of morphological changes, manifested in the form of a thin-walled cavity without pronounced infiltrative, focal and fibrous changes in the adjacent lung tissue.

The cavern is a constant source of infection and threatens the progression of the tuberculosis process with its transformation into fibrous-cavernous tuberculosis of the lungs. The development of fibrous-cavernous tuberculosis can be prevented by timely appointment and consistent implementation of a set of adequate treatment measures.

Fibrocavernous tuberculosis is characterized by the presence of one or more caverns with a well-formed fibrous layer in the walls, pronounced fibrous and polymorphic focal changes in the lung tissue.

Fibrocavernous tuberculosis is typically characterized by a chronic, wave-like, usually progressive course. At the same time, severe specific damage to the lung tissue with coarse fibrosis limits the possibilities of effective therapeutic impact on the pathological process.

There are three main types of fibrocavernous tuberculosis:

• limited and relatively stable;
• progressive:
• complicated.

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Epidemiology of cavernous and fibro-cavernous pulmonary tuberculosis

Cavernous and fibro-cavernous tuberculosis of the lungs mainly affects adults. In children with primary forms of tuberculosis: primary tuberculosis complex and tuberculosis of the intrathoracic lymph nodes - the formation of cavities is rarely observed.

Cavernous and fibrous-cavernous tuberculosis are diagnosed in 3% of newly diagnosed patients (of which cavernous - no more than 0.4%). Among patients observed for active tuberculosis in dispensaries, cavernous tuberculosis occurs in approximately 1%, fibrous-cavernous - in 8-10%.

Fibro-cavernous tuberculosis and its complications are the main cause of death in patients with pulmonary tuberculosis. Among patients who died from tuberculosis, fibro-cavernous tuberculosis was found in 80%.

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Pathogenesis of cavernous and fibro-cavernous pulmonary tuberculosis

The disintegration of lung tissue with subsequent formation of a cavity is possible with the progression of any form of pulmonary tuberculosis. This is facilitated by a decrease in general and immunological resistance against the background of additional sensitization, massive superinfection, addition of various diseases, drug resistance of mycobacteria.

Impaired immunity and the inevitable increase in the bacterial population are accompanied by increased exudation, development of microcirculatory disorders and damage to the surfactant system. Destroyed cellular elements form caseous masses filling the alveoli. Under the action of proteolytic enzymes secreted by leukocytes, caseous masses melt and undergo partial resorption by macrophages. When caseous masses are rejected through the draining bronchus, a pneumonigenic cavity of decay is formed. In other cases, the destructive process can begin with damage to the bronchus and the development of panbronchitis with subsequent destruction of the adjacent lung tissue and the formation of a bronchogenic cavity of decay. Another way of forming a bronchogenic cavity is the penetration of the pathogen into previously formed bronchiectasis.

The cavity of decay is directly surrounded by a wide layer of caseous-necrotic masses. Tuberculous granulations, mainly formed by epithelioid and giant cells, are adjacent to them on the outside. Over time, collagen fibers are formed in the outer part of the granulation layer, which form a thin fibrous layer with an uneven structure. As a result, a three-layer wall, characteristic of a cavern, appears around the cavity. The inner layer of the wall is formed by caseous-necrotic masses, the middle layer is represented by granulation tissue, and the outer layer is formed by concentrically located fibrous fibers. The formation of the cavern wall usually takes several months. Exceptions occur when caseous-necrotic masses are rejected from an encapsulated focus (tuberculoma). In this case, a cavity with a three-layer wall appears, in which there is already a previously formed fibrous layer.

A fresh (early, acute) cavity has a round or oval shape, surrounded by slightly changed lung tissue without significant inflammatory and fibrous changes. Such a cavity is typical for cavernous pulmonary tuberculosis.

Depending on the nature and specific mechanism of formation, proteolytic, sequestering, alterative and atheromatous caverns are distinguished. In cases where the melting of caseous masses begins in the center of the pneumonic focus and gradually spreads to the periphery, a proteolytic cavern is diagnosed. Melting of caseous masses in marginal areas with movement to the center of the caseous focus is a sign of a sequestering cavern. When caseous masses melt in encapsulated foci, atheromatous caverns occur. Sometimes the main cause of decay is impaired microcirculation and tissue nutrition in the area of tuberculous lesions with subsequent necrosis of individual areas. Such a formation mechanism is characteristic of an alterative cavern.

Due to the formation of a cavity, tuberculous inflammation usually spreads to the mucous membrane of the draining bronchus. Tuberculous granulations narrow its lumen and impede the movement of air from the cavity. As a result, its volume can increase significantly, and the cavity becomes "swollen". Deterioration of bronchial drainage makes it difficult to evacuate the contents of the cavity, increases the inflammatory reaction and general intoxication.

During treatment, the following variants of involution of a fresh cavern are possible:

• rejection of caseous-necrotic masses, transformation of the granulation layer into fibrous and healing of the cavity with the formation of a scar. This is the most perfect version of cavity healing;
• filling the cavity with granulation tissue and lymph, which are partially absorbed and then grow into connective tissue. As a result, a lesion or focus is formed;
• when eliminating tuberculosis inflammation in the draining bronchus and its cicatricial obliteration, air is sucked out of the cavern and it collapses. Conditions are created for reparative processes and the formation of a lesion or focus at the site of the cavern;
• while maintaining the normal structure and function of the draining bronchus, gradual epithelialization of the inner wall of the cavern occurs. However, the epithelium growing from the bronchus does not always line the cavern completely. This healing option is not entirely reliable;
• a combination of different paths of cavern involution is possible.

As cavernous tuberculosis progresses, caseous-necrotic inflammation spreads beyond the cavern wall, caseous lymphangitis and endobronchitis develop, and fresh foci of specific inflammation form in the pericavitary zone. Bronchogenic dissemination of mycobacteria causes the formation of tuberculous foci and foci in previously unaffected parts of the lung. The fibrous layer of the cavern wall gradually becomes thicker and denser, and fibrous changes develop in the adjacent lung tissue. The cavern wall is deformed, and the shape of the cavity becomes irregular.

Over time, the outer fibrous layer of the cavern wall becomes thick and continuous. The inner surface of the cavern wall is often uneven, the cavity may contain a small amount of mucopurulent contents with crumbs of caseous masses. Such a cavern is called fibrous or old. Its formation indicates the transformation of cavernous tuberculosis into fibrous-cavernous tuberculosis of the lungs.

At first, fibrous-cavernous tuberculosis may have a relatively limited extent and show no obvious tendency to progress (limited and relatively stable fibrous-cavernous tuberculosis). Later, the size of the fibrous cavern increases, the partitions between closely located caverns are destroyed and multi-chamber, often giant tuberculous caverns are formed. Blood vessels are located in the partitions dividing the cavern, and their destruction often leads to pulmonary hemorrhage. Foci of bronchogenic seeding in the lung tend to merge into foci with the gradual formation of new caverns. Over time, gross destructive, fibrous and degenerative changes of an irreversible nature are formed in the walls of the caverns, lung tissue and pleura. As a result of deformation and destruction of the bronchi, cylindrical and saccular bronchiectasis is formed, which is often filled with purulent contents. The branches of the pulmonary artery narrow and partially obliterate, and the bronchial arteries expand, especially near the walls of the caverns. This clinical form is designated as widespread progressive fibrous-cavernous pulmonary tuberculosis. In this form, empyema of the pleura and tuberculous lesions of other organs are often detected, in particular, sputum-cavernous tuberculosis of the larynx or intestine. Fibrous-cavernous tuberculosis may be accompanied by amyloidosis of the kidneys, liver, and spleen. Complicated course of fibrous-cavernous tuberculosis with the development of caseous pneumonia often leads to death.

Symptoms of cavernous and fibro-cavernous pulmonary tuberculosis

Cavernous tuberculosis of the lungs often develops against the background of insufficiently successful treatment of other forms of tuberculosis. Patients may be bothered by a cough with a small amount of mucous sputum: sometimes they note increased fatigue, decreased appetite, unstable mood. Such complaints are often renewed by a significant duration of previous treatment and a large drug load. In patients with newly diagnosed cavernous tuberculosis, complaints are usually absent. Percussion of the chest over the cavity area can determine a shortening of the percussion sound due to compaction of the pleura and lung tissue around the cavity. After coughing and deep inhalation, isolated wet and dry wheezing is sometimes heard over the affected area. In most patients, the caverns are "silent", i.e. they are not detected using physical examination methods.

Patients with fibrous-cavernous pulmonary tuberculosis are characterized by symptoms of intoxication, cough with sputum, sometimes with an admixture of blood, shortness of breath. They can have chest deformation, displacement of the mediastinal organs towards the lesion, pronounced and varied stethoacoustic symptoms. The severity of clinical manifestations of fibrous-cavernous tuberculosis changes in a wave-like manner depending on the phase of the tuberculosis process: an abundance of complaints during an exacerbation and a relatively satisfactory condition during short-term remissions.

Adequate treatment of fibrous-cavernous tuberculosis in most patients contributes to stabilization and limitation of the lesion. As a result of long-term treatment, pericavitary inflammation decreases, the granulation layer is partially sanitized, and tuberculous foci are absorbed. Such dynamics are more often observed with limited fibrous-cavernous tuberculosis.

X-ray picture of cavernous and fibro-cavernous tuberculosis of the lungs

In X-ray examination, tuberculous cavities are most often found in the upper parts of the lungs, where decay cavities are localized in many clinical forms preceding the development of cavernous tuberculosis. CT is considered the most informative method for diagnosing a cavity and the changes in the lungs that accompany it.

In cavernous tuberculosis, one rounded cavity no more than 4 cm in diameter is usually detected. The thickness of the cavity wall is 2-3 mm. The inner contour of the wall is clear, the outer one is often uneven and blurred, especially with persistent perifocal inflammation. When a cavity is formed from focal tuberculosis or tuberculoma, changes in the surrounding lung tissue are insignificant. Shadows of fibrous scars and foci are most often detected around cavities that have developed from infiltrative or disseminated pulmonary tuberculosis. The cicatrizing cavity has an irregular shape with strands to the root of the lung and pleura.

In fibro-cavernous pulmonary tuberculosis, the radiographic picture is varied and depends on the initial form of tuberculosis, the duration of the disease, the prevalence of the lesion and its features. One or more ring-shaped shadows, fibrous reduction of the affected parts of the lung, polymorphic focal shadows of bronchogenic seeding are detected. The diameter of the ring-shaped shadows varies from 2-4 cm to the size of a lung lobe, the shape can be rounded, but more often it is irregular or polycyclic (with the combination of several cavities). The outlines of the inner contour of the cavern wall are sharp, the outer contour against the background of compacted lung tissue is less clear. Sometimes a sequestrum or fluid level is determined in the lumen of the cavern.

In the upper lobe localization of the cavity, polymorphic foci and bronchogenic seeding foci are found in the lower parts of the lungs. In the affected area, there is local or diffuse fibrous cordiness with areas of increased transparency. A decrease in the volume of the affected lung leads to a shift of the mediastinal organs toward the affected side. The intercostal spaces narrow, the dome of the diaphragm rises. In the middle and lower parts of both lungs, foci of bronchogenic seeding are visible, which, with progression, turn into foci and cavities of decay.

In bilateral fibro-cavernous tuberculosis, formed from hematogenous disseminated, caverns and fibrous changes are localized in the upper parts of the lungs quite symmetrically. In the lower parts, the transparency of the lung fields is increased.

In the process of treating fibro-cavernous tuberculosis, positive changes are considered to be the resorption of infiltrative and focal changes in the lungs, a decrease in the thickness of the cavern wall. However, caverns usually remain and are well visualized on X-rays and CT.

Treatment of tuberculosis

• Chemotherapy for tuberculosis
• Anti-tuberculosis drugs
• Artificial pneumothorax
• Pneumoperitoneum
• Surgical methods of treatment of tuberculosis
• Treatment of extrapulmonary tuberculosis
• Pathogenetic therapy of tuberculosis
• Immunotherapy in the treatment of tuberculosis
• Physical methods of treating tuberculosis
• Methods of extracorporeal hemocorrection in tuberculosis
• Prevention of tuberculosis (BCG vaccination)
• Chemoprophylaxis of tuberculosis
• Sanitary and social prevention of tuberculosis