Tuberculosis (summary)

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This is a basic article for medical students and other non-radiologists

Tuberculosis is a non-bacterial multisystem infection that often affects the lungs. It may be a primary tuberculous infection, secondary infection or appear as chronic scarring. TB may also be seen on a chest x-ray as lymphadenopathy.

Reference article

This is a summary article; read more in our article on tuberculosis.

Summary

  • epidemiology
    • developing nations - adolescents and young adults
    • developed nations - immigrants, homeless and HIV infected
  • presentation
    • ​primary infection
      • usually asymptomatic
      • may feel generally unwell or have a small pleural effusion
    • post-primary infection​
      • when patients usually present to clinicians
      • systemic symptoms
        • malaise
        • weight loss
        • fever
        • night sweats
      • pulmonary symptoms
        • productive cough (mucopurulent or blood-stained)
        • shortness of breath
        • chest pain
      • ​extra-pulmonary symptoms
        • variable on location of lesions
      •
  • pathology
    • M. tuberculosis
      • ​aerobic mycobacterium that infects human lungs and organs
      • Gram staining ineffective due to waxy coating
    • ​primary infection
      • non-immune host exposed to M. tuberculosis
      • primary lesion usually occurs in the upper region of the lung
        • Ghon focus describes the initial granulomatous lesion 
      • Ghon complex is the calcified focus with associated mediastinal lymphadenopathy
      • most primary infections result in healing and calcification of the Ghon complex
      • healing leads to post-primary immunity and latent infection
  • post-primary infection (secondary tuberculosis)
    • harboured bacteria is reactivated after primary infection
      • occurs in immunocompromised individuals (e.g. HIV, steroid therapy, cytotoxic drugs)
    • lung infection causes patchy consolidation or cavitation
    • extra-pulmonary infection may involve meninges, bones, lymph nodes, urinary tract or GI tract
  • miliary tuberculosis
    • disseminated disease from TB infection in immunocompromised patients
      • may follow primary or post-primary infection
    • poor prognosis
  • presentation
    • ​primary infection
      • usually asymptomatic
      • may feel generally unwell or have a small pleural effusion
    • post-primary infection​
      • when patients usually present to clinicians
      • systemic symptoms
        • malaise
        • weight loss
        • fever
        • night sweats
      • pulmonary symptoms
        • productive cough (mucopurulent or blood-stained)
        • shortness of breath
        • chest pain
      • ​extra-pulmonary symptoms
        • variable on location of lesions
  • investigation
    • chest x-ray
    • sputum sample
      • Ziehl-Neelsen stain for acid-fast bacilli
      • culture for confirmation of diagnosis and sensitivity testing
    • HIV serology
    • lumbar puncture
      • investigation for TB meningitis 
    • blood tests
    • bronchoscopy
    • lumbar puncture
  • radiographic features (CT & CXR)
  • treatment
    • active TB
      • 4-drug regimen of rifampicin, isoniazid, pyrazinamide and ethambutol (2 months)
      • continuation of rifampicin and isoniazid (4 months)
    • latent TB
      • rifampicin and isoniazid (3 months)
      • OR isoniazid alone (6 months)
    • consideration of multidrug-resistant TB
  • screening and prevention
    • ​Mantoux test (tuberculin skin test)screening for latent tuberculosis
  • treatmentBCG vaccine
    • recommended for high risk groups
  • prevention
    • -<strong>epidemiology</strong><ul><li>​</li></ul>
    • +<strong>epidemiology</strong><ul>
    • +<li>developing nations - adolescents and young adults</li>
    • +<li>developed nations - immigrants, homeless and HIV infected</li>
    • +</ul>
    • +</li>
    • +<li>
    • +<strong>presentation</strong><ul>
    • +<li>​<a title="primary infection" href="/articles/primary-pulmonary-tuberculosis">primary infection</a><ul>
    • +<li>usually asymptomatic</li>
    • +<li>may feel generally unwell or have a small pleural effusion</li>
    • +</ul>
    • +</li>
    • +<li>
    • +<a title="post-primary infection​" href="/articles/post-primary-pulmonary-tuberculosis-1">post-primary infection​</a><ul>
    • +<li>when patients usually present to clinicians</li>
    • +<li>systemic symptoms<ul>
    • +<li>malaise</li>
    • +<li>weight loss</li>
    • +<li>fever</li>
    • +<li>night sweats</li>
    • +</ul>
    • +</li>
    • +<li>pulmonary symptoms<ul>
    • +<li>productive cough (mucopurulent or blood-stained)</li>
    • +<li>shortness of breath</li>
    • +<li>chest pain</li>
    • +</ul>
    • +</li>
    • +<li>​extra-pulmonary symptoms<ul><li>variable on location of lesions</li></ul>
    • +</li>
    • +</ul>
    • +</li>
    • +</ul>
    • -<em>M. tuberculosis</em><ul>
    • +<a href="/articles/mycobacterium-tuberculosis"><em>M. tuberculosis</em></a><ul>
    • -<em>​</em>aerobic mycobacterium that infects human lungs and organs</li>
    • +<em>​</em>aerobic mycobacterium</li>
    • -<li>primary lesion usually occurs in the upper region of the lung<ul><li>Ghon focus describes the initial granulomatous lesion </li></ul>
    • +<li>primary lesion usually occurs in the upper region of the lung<ul><li>
    • +<a href="/articles/ghon-lesion">Ghon focus</a> describes the initial granulomatous lesion </li></ul>
    • -<li>Ghon complex is the focus with associated mediastinal lymphadenopathy<ul><li>most primary infections result in healing and calcification of the Ghon complex</li></ul>
    • +<li>Ghon complex is the calcified focus with associated mediastinal lymphadenopathy</li>
    • +<li>most primary infections result in healing<ul><li>leads to post-primary immunity and latent infection</li></ul>
    • -<li>healing leads to post-primary immunity and latent infection</li>
    • -<li>miliary tuberculosis<ul>
    • +<li>
    • +<a href="/articles/miliary-tuberculosis">miliary tuberculosis</a><ul>
    • -<strong>presentation</strong><ul>
    • -<li>​primary infection<ul>
    • -<li>usually asymptomatic</li>
    • -<li>may feel generally unwell or have a small pleural effusion</li>
    • +<strong>investigation</strong><ul>
    • +<li>chest x-ray</li>
    • +<li>sputum sample<ul>
    • +<li>Ziehl-Neelsen stain for acid-fast bacilli</li>
    • +<li>culture for confirmation of diagnosis and sensitivity testing</li>
    • -<li>post-primary infection​<ul>
    • -<li>when patients usually present to clinicians</li>
    • -<li>systemic symptoms<ul>
    • -<li>malaise</li>
    • -<li>weight loss</li>
    • -<li>fever</li>
    • -<li>night sweats</li>
    • +<li>HIV serology</li>
    • +<li>lumbar puncture<ul><li>investigation for TB meningitis </li></ul>
    • +</li>
    • +<li>blood tests</li>
    • -<li>pulmonary symptoms<ul>
    • -<li>productive cough (mucopurulent or blood-stained)</li>
    • -<li>shortness of breath</li>
    • -<li>chest pain</li>
    • +<li>
    • +<strong>radiographic features (CT &amp; CXR)</strong><ul>
    • +<li>
    • +<a title="primary infection" href="/articles/primary-pulmonary-tuberculosis">primary infection</a><ul>
    • +<li>parenchymal consolidation</li>
    • +<li>lymphadenopathy</li>
    • +<li>pleural effusion</li>
    • +<li>Ghon complex</li>
    • -<li>​extra-pulmonary symptoms<ul><li>variable on location of lesions</li></ul>
    • +<li>
    • +<a title="post-primary infection" href="/articles/post-primary-pulmonary-tuberculosis-1">post-primary infection</a><ul>
    • +<li>patchy consolidation (upper zones)</li>
    • +<li>cavitation</li>
    • +<li>healing results in fibrosis</li>
    • +<li>pleural disease</li>
    • +</ul>
    • +<li>
    • +<a title="miliary tuberculosis" href="/articles/miliary-tuberculosis">miliary tuberculosis</a><ul>
    • +<li>1-3 mm diameter miliary nodules</li>
    • +<li>uniform size and distribution throughout both lungs</li>
    • +</ul>
    • +</li>
    • +<li>
    • +<a href="/articles/extrapulmonary-tuberculosis-1">extrapulmonary tuberculosis</a><ul>
    • +<li>
    • +<a href="/articles/tuberculoma">tuberculoma</a> within an affected organ</li>
    • +<li>widely variable</li>
    • -<strong>investigation</strong><ul>
    • -<li>chest x-ray</li>
    • -<li>sputum sample</li>
    • -<li>blood tests</li>
    • -<li>bronchoscopy</li>
    • -<li>lumbar puncture</li>
    • +<strong>treatment</strong><ul>
    • +<li>active TB<ul>
    • +<li>4-drug regimen of rifampicin, isoniazid, pyrazinamide and ethambutol (2 months)</li>
    • +<li>continuation of rifampicin and isoniazid (4 months)</li>
    • +</ul>
    • +</li>
    • +<li>latent TB<ul>
    • +<li>rifampicin and isoniazid (3 months)</li>
    • +<li>OR isoniazid alone (6 months)</li>
    • +</ul>
    • +</li>
    • +<li>consideration of multidrug-resistant TB</li>
    • -<strong>radiographic features</strong><ul><li>chest x-ray<ul><li> </li></ul>
    • -</li></ul>
    • +<strong>screening and prevention</strong><ul>
    • +<li>
    • +<strong>​</strong>Mantoux test (tuberculin skin test)<ul><li>screening for latent tuberculosis</li></ul>
    • +</li>
    • +<li>BCG vaccine<ul><li>recommended for high risk groups</li></ul>
    • +</li>
    • +</ul>
    • -<li><strong>treatment</strong></li>
    • -<li><strong>prevention</strong></li>
    • -</ul>
    • +</ul><p> </p><p> </p>
    Images Changes:

    Image 1 CT (lung window) ( create )

    Image 2 X-ray (Frontal) ( create )

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