Infiltrative pulmonary tuberculosis

Infiltrative pulmonary tuberculosis is a clinical form of tuberculosis that occurs against the background of specific hypersensitivity of the pulmonary tissue and a significant increase in the exudative tissue response in the inflammatory zone.

Clinical and morphological features of infiltrative tuberculosis are considered widespread lung damage with a tendency to rapid progression of the tuberculosis process.

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Infiltrative pulmonary tuberculosis: epidemiology

People with infiltrative tuberculosis are mostly adults, usually young. The likelihood of developing infiltrative tuberculosis increases with poorly organized detection of earlier forms of the disease. Infiltrative tuberculosis is diagnosed in 65-75% of newly diagnosed patients with pulmonary tuberculosis. Patients with this form make up 45-50% among patients with active tuberculosis, observed in anti-TB dispensaries.

In the structure of mortality from tuberculosis Infiltrative tuberculosis is about 1%. The lethal outcome of the disease is observed, mainly, with the development of complications: caseous pneumonia, pulmonary hemorrhage.

What causes infiltrative pulmonary tuberculosis?

The development of infiltrative tuberculosis is associated with the progression of focal tuberculosis, the appearance and rapid expansion of the infiltration zone around fresh or old tuberculosis foci. The spread of perifocal inflammation leads to a significant increase in the volume of damage to the lung tissue. A tuberculous infiltrate is a complex of fresh or old foci with an extensive area of perifocal inflammation. Infiltrates are more often localized in the 1-, 2-, and 6-m segments of the lung, i.e. In those departments where tuberculosis foci are usually located.

In terms of localization and volume of lung tissue damage, bronchopulmonary excretion, usually 2-3 pulmonary lobules, segmental (within one segment), as well as polysegmental or lobar infiltrates, are isolated. Infiltrate, which develops along the course of the main or additional interlobar fissure, is called periscisuritis.

A massive tubercular superinfection, accompanying diseases (diabetes mellitus, alcoholism, drug addiction, HIV infection) contribute to the intensification of the inflammatory reaction around the foci . These factors create the prerequisites for rapid growth in the number of microbial populations. Around the tuberculosis foci an inflammatory reaction develops with a pronounced exudative component. Specific inflammation extends beyond the pulmonary lobe, the total volume of lesions increases. So the bronchial fibroblast infiltrate is formed.

With relatively moderate disturbances of immunological reactivity, the intensity of exudation is relatively small, the cellular infiltration is moderately expressed. The alveoli are filled with macrophages, epithelioid and plasma cells and a relatively small amount of exudate. Inflammatory changes have a mixed exudative-proliferative character and spread relatively slowly. The area of tubercular inflammation is usually limited to the limits of the segment, in it an infiltrate is formed, which is commonly called round.

A significant weakening of local and general immunity contributes to higher rates of growth in the number of microbial populations. Hyperergic reaction of the lung tissue to a large population of virulent and rapidly multiplying mycobacteria causes pronounced exudation. Perifocal inflammation is characterized by the poverty of the cellular composition and the weakly expressed signs of specific inflammation. The alveoli are filled with a tissue fluid containing mainly neutrophils and a small number of macrophages. Expressed a tendency to progression of tuberculosis with rapid damage to many segments of the lung (cloud-like infiltrate). Further progression of immunological disorders is characterized by an increase in T suppressor activity and inhibition of HRT. Macrophage cells die, forming a zone of caseous necrosis. Caseous masses gradually melted and released into the drainage bronchus. So in the zone of progressive tubercular inflammation there is a site of destruction, limited by an inflamed-altered pulmonary tissue. Gradually formed cavity decay, which serves as a source of further bronchogenic and lymphogenous distribution of mycobacteria. Involvement in the pathological process of almost the entire lobe of the lung and the formation of multiple cavities of decay in the affected lobe testify to the formation of the lobite.

Over time, the differences between different infiltrates are largely lost. With a progressing course, infiltrative pulmonary tuberculosis is transformed into caseous pneumonia or cavernous tuberculosis.

The rate of regression of infiltrative tuberculosis depends on the nature of the exudate, the prevalence of the lesion, the extent of caseous necrosis, the reactivity of the patient's body. Infiltrates of small length with serous exudate against the background of adequate treatment can resolve relatively quickly. With serous-fibrinous or hemorrhagic exudate, resorption occurs more slowly and is combined with the development of fibrosis. Caseous masses as the resorption of infiltrative changes are condensed and drained. At the site of the decay cavity, a fibrous focus with inclusions of caseosis is formed. In the future, a linear or stellate scar can form on the site of the focus.

Symptoms of infiltrative pulmonary tuberculosis

In patients with a bronchodilator or round infiltrate, the symptoms of infiltrative pulmonary tuberculosis are mild (increased fatigue, decreased appetite, episodic body temperature increases), and the disease is often detected in a controlled medical examination.

A cloud-like infiltrate with lesions of one or more pulmonary segments and periscussuritis is usually characterized by a sharp onset with marked symptoms of intoxication, a small cough with sputum, sometimes hemoptysis. Involvement in the pathological process of the pleura leads to the appearance of pains in the chest on the side of the lesion, which are associated with respiratory movements. Further progression of tubercular inflammation with the development of the lobite is characterized by a sharp deterioration in the patient's condition, increased intoxication and respiratory symptoms.

Stethoacoustic changes in patients with bronchodilator and round infiltrate, as a rule, are absent. With a cloud-like infiltrate, periscussurate. Lobite it is possible to reveal a shortening of percussion sound over the zone of injury, an increase in vocal trembling, bronchial breathing. Sometimes a few damp little bubbling rales are listened to, and above the cavity of disintegration are unstable mild wheezing, which often appear only on inspiration after coughing up the patient.

Diagnosis of infiltrative pulmonary tuberculosis

X-ray diagnostics of infiltrative pulmonary tuberculosis allows the establishment of a clinical-x-ray type of infiltrate and a number of details of the lesion.

When bronholobulyarnom infiltrate in the cortical zone of the pulmonary field, more often in the 1-, 2- or 6-th segments, identify a limited darkening, often of low intensity, with diffuse contours, up to 3 cm in size. The infiltrate has a polygonal shape elongated towards the root of the lung . CT scan can reveal the lumen and division of the small bronchus around which the infiltrate was formed. Bronchial lumen is sometimes filled with dense caseous masses. On the tomogram, the bronchial fibroblast infiltrate often looks like a conglomerate of several more or less dense small foci, united by a zone of perifocal inflammation.

Rounded infiltration is represented by a limited diminution of rounded shape, mainly of medium intensity with clear, but unsharpened outlines. In the subclavian region, the classical type of the Asmann-Redeker infiltrate is localized.

From the medial parts of the darkness, the inflammatory pathway to the lung root leaves, in which the projection of the draining bronchus (the symptom of the "tennis racket") is sometimes revealed. When the infiltrate breaks down in its central regions, cavities are usually identified. In the lower parts of the lungs, foci of bronchogenic seeding can often be seen.

The cloud-like infiltration on the roentgenogram looks like an uneven blackout. Limited to the limits of one or more segments and not having clear boundaries. When the infiltrate is localized in the interlobar fissure (periscisuritis), it approaches a triangular shape with a diffuse upper border and a rather distinct lower one, which runs along the intersecting fissure. CT allows us to consider the structure of the infiltrate formed during the fusion of many foci. For a cloud-like infiltrate is characterized by the presence in the affected area of several small cavities of decay, limited inflammatory-compacted pulmonary tissue, possibly the formation of large cavities.

With lobar infiltration (lobit), the location and shape of the shading depends on how much of the lung is affected. On CT scan lobit sometimes is visualized as a continuous, almost uniform compaction of the lobe fraction. In the affected part, the bronchi are deformed and partly surrounded by caseous masses, and also multiple cavities of disintegration of small and medium diameter ("honeycomb" or "bread crumb"). With the progression of the lobite, focal dissemination is often detected) in the opposite lung, mainly in the 4th and 5th segments.

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