secondary_TB_eng_2015-2016-64681

Secondary Pulmonary Tuberculosis

Pathogenic Particularities

  • Occurs more frequently in adults due to:

    1. Reactivation of latent TB infection (endogenous reinfection)

      • Located in postprimary TB sequelae, intrathoracic lymph nodes

      • Requires decreased host immunity

    2. Exogenous infection with bronchogenic extension

      • Leads to lung destruction and chronic evolution

      • Reactivates latent TB due to delayed hypersensitivity immune reaction

Development of Secondary TB

  • Lesion Formation:

    • Typically in upper parts of lungs

    • Hilar lymph nodes usually absent

    • Lung and lymph node lesions may heal and calcify

    • Gradual enlargement of lesions leading to caseation and cavity formation

    • Following effective treatment, fibrosis may develop in lesion areas

Disseminated Pulmonary Tuberculosis

  • Definition:

    • Complication of primary TB in children/adolescents and secondary TB in adults

    • Characterized by micronodular lesions and variable sized nodules

    • Infection spreads via hematogenous, lymphogenous, and bronchogenous pathways

    • Occurs in 10% of TB cases

Clinical Forms

  • Sharpest form: Sepsis tuberculosis (tifobacilosis Landuzi)

  • Acute, subacute, and chronic disseminated tuberculosis variations.

Clinical Presentation of Acute Form

  • Develops in young adults with immune risk factors (low social status, alcoholism)

  • Symptoms include high fever (39-40°C), severe intoxication, cough, dyspnea

  • Poor prognosis leading to potential death

Miliary Tuberculosis

  • Onset: Often acute with symptoms varying by form:

    1. Typhoid Form:

      • Severe generalized condition, fever (39-40°C), distinct from typhoid fever

    2. Meningeal Type:

      • Symptoms similar to meningitis: high fever, headache, vomiting

      • Less pronounced meningeal signs

    3. Pulmonary Type:

      • Predominant symptoms include dyspnea, cyanosis, ARDS

Radiological Features

  • Tiny spots in the lungs resembling millet seeds, often appearing in a "starry sky" pattern.

Chronic Disseminated Tuberculosis

  • Characterized by long evolution with remissions and exacerbations

  • Symptoms: fever, weight loss, cough, dyspnea

Physical Examination Findings

  • Patient may appear older, with pale skin and reduced muscle tone

  • May present with barrel-shaped chest, dullness, and diminished breath sounds

Diagnosis

  • Sputum smear is often positive

  • Tuberculin skin test typically positive

  • Blood analysis may show anemia, leukocytosis

Differential Diagnosis

  • Includes metastatic tumors, bronchiolitis, pulmonary stasis disease

Fibrous-Cavernous Pulmonary Tuberculosis

  • Secondary TB form involving thick-walled cavities and fibrotic tissue

  • Complicated with chronic evolution, leading to multiple health risks

Complications of TB

  • Reversible: Spontaneous pneumothorax, pulmonary hemorrhage, pleurisy

  • Irreversible: Pulmonary fibrosis, chronic respiratory failure, bronchiectasis

Summary of TB Types

  1. Secondary Pulmonary Tuberculosis: Occurs from reactivation of latent TB.

  2. Disseminated Pulmonary Tuberculosis: Complication of primary TB and secondary in adults, marked by micronodular lesions.

  3. Chronic Forms: Evolving, fibro-cavernous tb with potential severe complications.