Main Forms of Secondary Tuberculosis
Secondary tuberculosis proceeds with deep destruction of the lung tissue. In pathological anatomy practice, special attention is paid to two severe forms:
- Fibro-cavitary tuberculosis. According to autopsy data, this is the most common form. Patients actively shed M. tuberculosis into the environment, making them maximally hazardous to the healthy population. Management of such patients requires prolonged chemotherapy and strict isolation.
- Cirrhotic tuberculosis. Represents the terminal stage of the disease. The main morphological feature is the massive development of scar tissue. A dense linear scar forms at the site of a healed cavity. Marked focal or diffuse pulmonary sclerosis is observed in the lungs. The organ is severely deformed, loses its mobility, and becomes very dense. Interpleural adhesions and numerous bronchiectasis are frequently formed. The prognosis is extremely unfavorable: recovery at this stage is virtually impossible.
Routes of Infection Spread
In secondary tuberculosis, mycobacteria spread through the body via several pathways, affecting adjacent and distant organs:
- Canalicular and contact routes. The infection spreads to the bronchi, trachea, larynx, oral cavity, and gastrointestinal tract.
- Tuberculosis of the bronchi is accompanied by cough and minor hemoptysis. Such patients are extremely contagious.
- Laryngeal tuberculosis usually accompanies advanced pulmonary forms. Bacteria settle on the mucous membrane during expectoration of sputum. The process follows strict stages: it begins with superficial laryngitis, followed by ulceration, and finally granulation tissue forms (sometimes involving the epiglottis). The main clinical symptom is dysphonia.
- Gastrointestinal involvement (tuberculous ileitis). Normally, the stomach serves as a reliable barrier, so simple swallowing of bacilli does not cause disease. However, in extensive destructive pulmonary processes and severe bodily exhaustion, a sputum-borne (sputogenous) lesion develops (from Latin sputum). The patient constantly swallows infected sputum, leading to ulcer formation in the cecum and ileum.
- Hematogenous route. This is atypical for secondary tuberculosis and occurs rarely. Spread of infection via the bloodstream occurs predominantly in the terminal period when the body's defense mechanisms are critically reduced.
Fatal Complications
Most severe complications of secondary tuberculosis are directly related to the presence of destructive cavities:
- Pulmonary hemorrhage. Occurs when the walls of large blood vessels are damaged within the tissue breakdown zone. Repeated episodes of hemorrhage can cause death from post-hemorrhagic anemia.
- Cavity rupture. If the cavity contents rupture into the pleural cavity, it provokes pneumothorax, pleuritis, tuberculous empyema, and the formation of persistent bronchopleural fistulas.
- Secondary amyloidosis. Develops as a consequence of a prolonged undulating pulmonary course or chronic destructive extrapulmonary tuberculosis. This complication is particularly characteristic of the fibro-cavitary form. Amyloid accumulation can lead to death from renal failure.
- Chronic cor pulmonale. Forms against the background of chronic inflammation, emphysema, and pulmonary sclerosis. Death in this case results from progressive chronic cardiopulmonary failure.
Residual Changes After Healing
It is important to understand that lung tissue after recovering from tuberculosis never returns to its baseline state. Residual morphological manifestations always persist: chest deformation, coarse scars, focal or diffuse pulmonary sclerosis, and encapsulated calcified nodules (calcifications).
Clinical significance of these changes is immense. Within calcifications, the infection can enter a dormant state, and its complete absence cannot be ruled out. Although carriers of such changes subjectively feel completely healthy, they actually remain infected patients. They face a constant risk of developing active tuberculosis.