Infiltrative pulmonary tuberculosis is a secondary tuberculosis infection characterized by widespread lung damage with an exudative type of inflammatory reaction and the formation of foci of caseous decay. The clinical picture is dominated by intoxication syndrome, hyperthermia, productive cough, side pain, hemoptysis. In the diagnosis of infiltrative pulmonary tuberculosis, the data of physical, X-ray, laboratory examination, the results of tuberculin tests are informative. Treatment is inpatient, with specific chemotherapy with anti-tuberculosis drugs.
Causes of infiltrative pulmonary tuberculosis
The origin of infiltrative pulmonary tuberculosis is based on one of two mechanisms: endogenous reactivation or exogenous superinfection. Reactivation is characterized by the progression of old or fresh foci of tuberculosis, the appearance of an infiltration zone around them and the development of an exudative tissue reaction. Exogenous superinfection, as the cause of infiltrative pulmonary tuberculosis, is associated with the presence of hypersensitivity sites in the lungs (i.e., areas previously in contact with tuberculosis infection). With repeated massive ingestion of Mycobacterium tuberculosis in these foci, a hyperergic reaction develops, accompanied by infiltrative inflammation. In both cases, a prerequisite for morbidity is the presence of a specific anti-tuberculosis (secondary) immunity at the time of infection.
The category of increased risk for the development of infiltrative pulmonary tuberculosis consists of persons who have had contact with a bacillus separator, neuropsychiatric trauma; suffering from alcoholism, nicotine addiction, HIV infection, drug addiction; leading an antisocial lifestyle; having chronic diseases (diabetes mellitus, etc.) and occupational diseases; undergoing hyperinsolation, etc.
Initially, an infiltrate with a diameter of about 3 cm is formed in the lung tissue, the boundaries of which tend to expand until several segments or an entire lobe of the lung are affected. The infiltrate is a focus of polymorphic exudation consisting of fibrin, mononuclears, macrophages, polymorphonuclear leukocytes, alveolar epithelium. When the infiltrates merge and expand, specific lobar pneumonia or bronchopneumonia occurs.
At the next stage, the infiltration sites are subjected to caseous melting. Treatment of infiltrative pulmonary tuberculosis can contribute to the complete resorption of the infiltrate, scarring of areas, encapsulation of the infiltrate zone with the formation of pulmonary tuberculoma. In case of further progression of infiltrative tuberculosis, two development options are possible: transition to caseous pneumonia (obsolete. – “transient consumption”) or the disintegration of lung tissue with the formation of cavities (cavernous tuberculosis).
In modern phthisiology, it is customary to distinguish five clinical and radiological variants of infiltrative pulmonary tuberculosis:
- Oblakoid infiltrate – radiologically determined in the form of a low-intensity homogeneous shadow with vague contours. It has a tendency to rapid decay and the formation of fresh cavities.
- Round infiltrate – on radiographs it has the form of a rounded homogeneous focus (sometimes with a decay site in the form of enlightenment) with clearly defined boundaries; more often it is localized in the subclavian region.
- Lobular infiltrate – when X-ray examination reveals inhomogeneous darkening of irregular shape, formed by the fusion of several foci, often with decay in the center.
- Marginal infiltrate (periscissuritis) is an extensive oblacoid infiltration, bounded from below by an interlobular furrow. It has a triangular shape with an angle facing towards the root of the lung, and the base is outward. Often there is a lesion of the interlobular pleura, sometimes with the development of tuberculous pleurisy.
- Lobitis is an extensive infiltrate in the lung, occupying an entire lobe. Radiologically characterized by inhomogeneous focus with the presence of decay cavities in it.
Small (1-2 cm), medium (2-4 cm), large (4-6 cm) and common (more than 6 cm) infiltrates are distinguished by size. Caseous pneumonia is distinguished separately, characterized by an infiltrative reaction with a predominance of necrotic processes. Caseous-pneumonic foci affect the lobe or the entire lung. Caseous pneumonia develops more often against the background of diabetes mellitus, pregnancy, pulmonary bleeding, accompanied by aspiration of blood seeded with mycobacteria.
Infiltrative pulmonary tuberculosis symptoms
The variant of the clinical course depends on the type of infiltration. Acute onset is characteristic of lobitis, periscissuritis, and some cases of oblacoid infiltration. Asymptomatic and low-symptomatic course is observed in the presence of round, lobular and oblacoid infiltrates. In general, acute manifestation is observed in 15-20% of patients, gradual – in 52-60%, asymptomatic – in 25% of cases.
In most cases, the first nonspecific symptom of infiltrative pulmonary tuberculosis is a rise in body temperature to 38-38.5 ° C, which lasts 2-3 weeks. Hyperthermia is accompanied by sweating, muscle soreness, bruising, cough with sputum. In general, the clinic resembles the flu, bronchitis or acute pneumonia. Sometimes the disease manifests with hemoptysis or pulmonary bleeding. Among the most common complaints should be noted chest pain on the affected side, decreased appetite, sleep disorder, general weakness, palpitations. Asymptomatic and low-symptomatic forms of infiltrative pulmonary tuberculosis are usually detected during a medical examination or preventive medical examination based on the results of fluorography.
Complications of infiltrative pulmonary tuberculosis include caseous pneumonia, lung atelectasis, pneumothorax, pleurisy, pulmonary hemorrhage, tuberculous meningitis, reactive myocarditis, heart failure. The onset of caseous pneumonia is always acute: fever reaches 40-41 ° C, typical differences between daytime and evening temperatures, pronounced tuberculosis intoxication. Patients are concerned about shortness of breath, cough with purulent sputum, chest pain, progressive weight loss.
Since the clinical signs of infiltrative pulmonary tuberculosis are not specific or absent at all, objective, instrumental and laboratory data are of primary importance in the diagnosis. The auscultative picture is characterized by the presence of sonorous wheezing; percussion detects a dulling of sound over the infiltrate area. These changes are especially pronounced in lobitis and the presence of infiltrate decay with the formation of a cavity. Inflammatory changes in the blood (shifts in the leukoformula, acceleration of ESR) are insignificant.
The tuberculin test in patients is more often positive. Radiography of the lungs allows not only to detect infiltrative changes, but also to assess the nature of the shadow, to trace the dynamics of treatment. MBT can be detected both by microscopic examination and by bacteriological seeding of sputum or bronchial flushing waters obtained during bronchoscopy. New, highly reliable blood tests allow to confirm the presence of tubinfection in the body: T-SPOT.TB and quantiferon test.
It is necessary to differentiate infiltrative pulmonary tuberculosis with focal tuberculosis, acute respiratory infections, nonspecific pneumonia, lung cancer, actinomycosis, echinococcosis and lung cysts, lymphogranulomatosis.
Treatment for infiltrative pulmonary tuberculosis
Patients with infiltrative pulmonary tuberculosis are immediately hospitalized in an anti-tuberculosis facility, where they are under the supervision of a phthisiologist. Patients are prescribed pathogenetic therapy with specific chemotherapy drugs (isoniazid, pyrazinamide, rifampicin, ethambutol). Treatment continues for several months; the criterion for discontinuation of therapy is complete resorption of infiltrative changes according to X-ray data; in the future, anti-relapse courses of anti-tuberculosis therapy are carried out on an outpatient basis.
At the same time, immunomodulators, antioxidants, corticosteroids are prescribed. In conditions of rational treatment, clinical symptoms disappear after an average of 3-4 weeks; bacterial excretion stops within 1 to 4 months; reduction and resorption of infiltration, closure of cavities occurs by 3-4 months. With infiltrative pulmonary tuberculosis in the decay phase, the question of surgical treatment – operative collapse therapy may be raised.
A variant of the prognosis of infiltrative tuberculosis may be a favorable outcome – resorption of the infiltrate with residual fibrococcal changes in the lungs; less often – complete resorption of the infiltrative focus. Unfavorable outcomes include the formation of pulmonary tuberculoma, the transition to caseous pneumonia or fibrous-cavernous tuberculosis, death from increasing tuberculosis intoxication or other complications. In modern conditions, when conducting anti-tuberculosis therapy, unfavorable outcomes are rare.
Prevention of infiltrative pulmonary tuberculosis does not differ from measures to prevent the incidence of other forms of tuberculosis infection. Since patients with the infiltrative form are bacillus separators, it is necessary to identify, isolate and treat them as early as possible.