Primary (Nonimmune) Tuberculosis

The prevalence of acute primary infection at any age, even without AIDS, is one of the major variations in tuberculosis in the tropics compared with other regions. In one series, more than 50% of the patients with the primary pattern of tuberculosis were over 18 years of age. Clinically patients may present with an acute illness which may be so severe that its true cause is not easily recognized. Other patients may seem to have a simple upper respiratory infection, perhaps one which does not improve clinically, and primary lung tuberculosis is an unexpected finding on a chest radiograph. There are five ways in which primary tuberculosis presents radiographically:

- Lobar pneumonia
- Bronchopneumonia
- Hilar and mediastinal adenopathy
- Pleural or pericardial effusion
- Miliary tuberculosis

Any of these patterns may appear on the first chest radiograph, separately or in any combination. In patients with poor immunity for any reason, the primary infection may never heal but continue on to severe cavitating, spreading pneumonia (Fig. 5.3). This is progressive primary tuberculosis. The majority of primary infections, however, heal with little residual scarring; only a few will imperceptibly change to the secondary, or immune, pattern of tuberculosis with resulting fibrosis, distortion, and calcification. There is one particular end result, a "destroyed lung" or lobe. This outcome is common in the tropics; it is particularly frequent in Africa and India, but has also been seen in Asia, Australia, Hawaii, and South America. It occurs in children as well as in adults.

Fig. 5.3. Progressive primary tuberculosis. Right upper lobe tuberculous pneumonia has progressed, with central necrosis, and become a large tuberculous lung abscess. There is a small overlying pleural reaction. Shortly after this film was taken, the child developed an acute pneumothorax that required surgical decompression. (Courtesy of Semin Roentgenol, 1979)