Main forms of secondary tuberculosis
Secondary tuberculosis proceeds with deep damage to the lung tissue. In pathological anatomical practice, special attention is paid to two severe forms:
- Fibrocavernous tuberculosis. According to autopsy data, this is the most common form. Patients actively excrete M. tuberculosis into the environment, thus posing a maximum threat to the healthy population. Management of such patients requires prolonged chemotherapy and strict isolation.
- Cirrhotic tuberculosis. This represents the final stage of the disease. The main morphological feature is the massive development of scar tissue. A dense linear scar forms at the site of the healed cavity. Pronounced focal or diffuse pneumosclerosis is observed in the lungs. The organ is severely deformed, loses mobility, and becomes very dense. Interpleural adhesions and numerous bronchiectasis frequently form. The prognosis is extremely unfavorable: curing patients at this stage is practically impossible.
Routes of infection generalization
In secondary tuberculosis, mycobacteria spread through the body via several routes, affecting neighboring 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 sputum expectoration. The process goes through strict stages: it begins with superficial laryngitis, then ulceration occurs, and in the final stage, granulomas form (sometimes the epiglottis is involved). The main clinical symptom is dysphonia.
- Gastrointestinal tract involvement (tuberculous ileitis). Normally, the stomach serves as a reliable barrier, so mere swallowing of bacilli does not cause the disease. However, with an extensive destructive process in the lungs and marked physical exhaustion, sputum-borne involvement develops (from the Latin sputum — sputum). The patient constantly swallows infected sputum, which leads to the formation of ulcers in the cecum and ileum.
- Hematogenous route. This is atypical for secondary tuberculosis and occurs rarely. The spread of infection through the bloodstream occurs predominantly in the terminal period, when the body's defenses are critically reduced.
Fatal complications
Most severe complications of secondary tuberculosis are directly related to the presence of destructive cavities:
- Pulmonary hemorrhages. They occur when the walls of large blood vessels are damaged in the tissue destruction zone. Repeated episodes of bleeding can cause death from posthemorrhagic anemia.
- Rupture of the cavity. If the contents of the cavity rupture into the pleural cavity, this provokes the development of pneumothorax, pleurisy, tuberculous empyema, and the formation of persistent bronchopleural fistulas.
- Secondary amyloidosis. It develops as a consequence of a prolonged undulating course of the pulmonary process or chronic destructive extrapulmonary tuberculosis. This complication is particularly characteristic of the fibrocavernous form. The accumulation of amyloid can lead to death from renal failure.
- Chronic cor pulmonale. It forms against the background of persistent chronic inflammation, emphysema, and pneumosclerosis. Death in this case ensues from progressive chronic cor pulmonale failure.
Residual changes after recovery
It is important to understand that lung tissue never returns to its baseline state after overcoming tuberculosis. Residual morphological manifestations always persist: chest deformity, rough scars, focal or diffuse pneumosclerosis, as well as encapsulated calcifications.
The clinical significance of these changes is enormous. Inside calcifications, the infection can enter a "dormant" state, and it is impossible to completely rule out its presence. Although carriers of such changes subjectively feel absolutely healthy, they effectively remain infected patients. They retain a constant risk of developing active tuberculosis.
Briefly: answers to topical questions
What forms of secondary tuberculosis are distinguished in pathological anatomy?
In pathological anatomy, 8 morphological forms of secondary tuberculosis are distinguished, which represent successive phases transitioning into one another:
- acute focal;
- fibro-focal;
- infiltrative;
- tuberculoma;
- caseous pneumonia;
- acute cavernous tuberculosis;
- fibro-cavernous;
- cirrhotic.
What is the macroscopic and microscopic picture of the cavity wall in fibro-cavernous tuberculosis?
Macroscopically, the cavity wall in fibro-cavernous tuberculosis is thick and dense, the inner surface is uneven and contains caseous masses, while the lumen is crossed by sclerosed blood vessels and bronchi. The microscopic picture has a layered structure:
- Inner layer — a focus of caseous necrosis (cheesy masses) containing M. tuberculosis and remnants of destroyed tissue.
- Middle layer — specific granulation tissue with an accumulation of epithelioid cells, lymphocytes, and multinucleated Pirogov–Langhans giant cells.
- Outer layer — a dense fibrous (connective tissue) capsule.
What is the fundamental difference between secondary and primary tuberculosis?
Secondary tuberculosis is more common in adults, whereas primary tuberculosis is traditionally more common in infants and children. In primary tuberculosis, a primary tubercular complex is formed, including the primary affect, lymphangitis, and lymphadenitis. Secondary tuberculosis is characterized by an isolated lung lesion without lymph node involvement; the process usually begins in the apical segments I and II of the right, less frequently the left, lung. Secondary tuberculosis can be associated with the reactivation of old foci or reinfection.
To memorize the fatal complications of secondary tuberculosis, use the acronym KARK: Bleeding (pulmonary), Amyloidosis (secondary), Rupture of the cavity, Cor pulmonale (chronic pulmonary heart).
Class and exam questions
Why can the intestine be affected in pulmonary tuberculosis?
With extensive destruction of lung tissue, the patient swallows infected sputum (sputum). The gastric barrier is overcome against the background of exhaustion, and mycobacteria cause ulcerative lesions of the ileum and cecum (sputogenic ileitis).
Why are encapsulated calcifications dangerous after healing?
A "dormant" infection may persist in them. The person considers themselves healthy, but in fact remains infected with a constant risk of tuberculosis relapse.
Which form of secondary tuberculosis is considered the terminal one?
Cirrhotic tuberculosis. In this condition, scars form in place of the cavities, the lung becomes deformed and dense, and bronchiectasis and pneumosclerosis develop.
What else to study on this topic
- Morphological picture of cirrhotic tuberculosis
- Stages of development of laryngeal tuberculosis
- Pathogenesis of secondary amyloidosis in the fibro-cavernous form
- Mechanism of chronic cor pulmonale formation
- Sputum-borne lesion of the gastrointestinal tract
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