2.1 Pulmonary tuberculosis (PTB)


Certain signs of PTB are quite typical: prolonged cough (lasting more than 2 weeks) and sputum production, while others are less so: weight loss, anorexia, fatigue, shortness of breath, chest pain, moderate fever, and night sweats.

Haemoptysis (blood in sputum) is a characteristic sign present in about one third of patients1,2.

All these signs are variable and evolve in a chronic, insidious manner. History taking and questioning the patient are therefore of the utmost importance.

Advanced forms and complications are not uncommon. These include:
– Respiratory insufficiency due to extensive lesions and destroyed lungs;
– Massive haemoptysis due to large cavities with hypervascularisation and erosion of vessels;
– Pneumothorax due to the rupture of a cavity in the pleural space.

In an endemic area, the diagnosis of PTB is to be considered, in practice, for all patients who have experienced respiratory symptoms for more than 2 weeks.

Table 2.1 provides a differential diagnosis of PTB for non-HIV infected patients.

Table 2.1 - Differential diagnosis for PTB (non-HIV infected patients)

Diseases

Comments

Bacterial pneumonia

  • Usually more acute and shorter in duration; high fever often present.
  • Response to broad-spectrum antibiotics with no anti-TB activity suggests bacterial pneumonia.
  • Lobar consolidation is typical of bacterial pneumonia, however, X-ray alone cannot differentiate TB from bacterial pneumonia.

Pulmonary abscess

  • Usually arises from aspiration in individuals with impaired consciousness (coma, intoxication with alcohol/drugs, etc.).
  • Bad smelling, purulent sputum.
  • Cavities typically have a thick-wall and air-fluid levels.

Bronchectiasis

  • Frequent complication of successive, poorly treated bronchopulmonary infections in tropical regions.
  • Haemoptysis, usually mild, can be present.

Lung cancer

  • History of smoking or exposure to environmental toxins (working in a mine, etc.).
  • Haemoptysis in 20 to 50% of patients.

Paragonimiasis
(lung flukes)

  • To be ruled out in TB suspect cases in endemic areas (certain areas of South- Eastern Asia, Western Africa and Latin America).

Pulmonary echinococcosis
(hydatid disease)

  • In Latin America, the Middle East, some sub-Saharan African countries, China.
  • Lung involvement may cause chronic cough with or without haemoptysis.
  • Cysts can mimic TB cavities.

Pneumocystosis

  • In imunocompromised patients on corticosteroids or cancer chemotherapy agents.

Less common diseases

  • Silicosis, sarcoidosis, berryliosis, melioidosis, cryptococcosis, aspergillosis, histoplasmosis.

For differential diagnosis in HIV-infected patients, see Section 2.4.