Clinical Characteristics

Clinical tuberculosis is so well described in so many textbooks that there is little reason to repeat the findings. To the usual picture of malaise, tiredness, loss of weight, night sweats, and mild pyrexia must be added two important tropical variants: the acute form of the disease and the background of ill health which is so common in many of the tropical patients.

Ill health, anemia, malnutrition, pyrexia, and dysentery are so much a normal part of the low standard of living and hygiene of many tropical countries that these conditions cannot be used as an indication of possible tuberculosis. For example, in Egypt and elsewhere in Africa, many adults in rural areas normally have several varieties of parasites and this is equally true for much of India, Asia, and South America. This background of ill health makes the patient more susceptible to tuberculosis and the delicate balance of borderline ill health may have been upset by a recent tuberculous infection which has brought the patient to the physician.

In other patients, acute tuberculosis, whether in lungs or in joints or elsewhere in the body, may closely mimic an acute bacterial infection. The classical presentation of a low-grade illness is not the only way in which tuberculosis behaves. The history of the illness may be short, as when a child who has a temperature of 39.5° C (103° F) seems to have acute bacterial lobar pneumonia but actually has primary tuberculosis. Initial examination of the sputum (or gastric lavage) in such cases may be confusing because of secondary infection: the diagnosis of tuberculosis may not be made because the possibility is often forgotten. Similarly, acute osteomyelitis, septic arthritis, mastoiditis, and peritonitis may all be due to tuberculosis and not an "ordinary" pyogenic infection. There must be a high index of suspicion and clinical sixth sense, and tuberculosis should be included in almost every differential diagnosis.

Tuberculosis of the Respiratory Tract

Even before AIDS swept through the tropics, pulmonary tuberculosis had been one of the major causes of illness and death: it is not likely to relinquish this leading role for many years, even in the millions who are HIV-negative.

Tuberculosis of the Upper Respiratory Tract

The possibility of tuberculosis of the upper respiratory tract should always be considered in a patient from whom the sputum has been found to contain tubercle bacilli and yet the routine chest radiograph is normal. Clinically there will be excess sputum, hoarseness, and, usually, general symptoms of tuberculosis. Endoscopy, computed tomography (CT), and, in some cases, a contrast tracheogram will demonstrate the tuberculous ulceration and granulation tissue (when CT is not available, standard tomography can be helpful) (Figs. 5.1, 5.2). The trachea may be narrowed, the larynx swollen, and the cartilage eroded, all of which can be demonstrated on CT. Active tuberculosis is always much more extensive on CT scanning than it appears on endoscopy. Quite often the whole length of the trachea is thickened and it may extend into the major bronchi. The thickening is irregular, and where there is an intraluminal granulomatous mass, the degree of narrowing can be quite significant. The extent of the infection is most clearly seen on three-dimensional imaging, but actual images often show the relationship of the neighboring structures.

The fibrotic stage of tuberculosis usually results in smooth narrowing of the lumen and the thickening of the wall is less marked. When the disease spreads down to the main bronchi, the left main bronchus is often more involved.

Although pulmonary tuberculosis is common, laryngeal and tracheal infection are not, even as a complication in patients with heavily infected sputum. As an isolated infection, without pulmonary tuberculosis, laryngeal or tracheal tuberculosis is rare. While the granulomas can be imaged, there is no satisfactory radiological method to confirm that the etiology is tuberculosis.

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Fig. 5.1. A Laryngeal and subglottic tuberculosis in a 3-year-old girl from one of the Pacific Islands. There is narrowing and anterior displacement of the airway. The diagnosis was confirmed by bronchoscopy: both lungs showed miliary tuberculosis and there was tuberculous thickening of the ileocecal region also. Upper airway infection is usually part of generalized, hematogenous spread and this case was no exception. (Courtesy of Dr. Cheryl Sisler, Honolulu, Hawaii) B Linear tomograms of laryngeal tuberculosis which presented in an adolescent as upper airway obstruction. There was a granulomatous mass lesion in the larynx. (From Cremin and Jamieson 1995).

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Fig. 5.2 A-F. Tuberculosis of the trachea and major bronchi is best shown with multiplanar and three-dimensional reconstruction. A An irregular mass narrowing the trachea, with marked thickening of the whole length of the tracheal wall. B Three-dimensional CT scan of the same patient confirms the irregular and diffuse narrowing of the whole length of the trachea and the proximal main bronchi. C Thin-section CT, at the level of the thoracic inlet, clearly showing the marked thickening of the wall of the trachea and the narrow lumen. In the fibrotic stage, the distortion may be even more marked. D Three-dimensional CT scan of a 29-year-old woman shows marked irregular narrowing along the length of the left main bronchus. E A thin-section CT scan of the same patient, just below the carina, confirms the narrowing of the lumen and shows the marked thickening of the wall of the bronchus. F The coronal scan shows the full extent of the bronchial fibrosis. (Courtesy of Dr. Kyung Soo Lee, Samsung Medical Center, Seoul).