Recognising tuberculosis in the lower lung field: an age- and sex-matched controlled study

Tuberculosis (TB) can sometimes present with consolidation in the lower lung field. This study was conducted to compare the manifestations of lower-lung-field TB (LLFTB) and other pulmonary TB.

All new culture-proven TB patients with lower-lung-field consolidation from July 2001 through December 2002 were included. Age- and sex-matched TB patients with upper lung involvement were selected as controls.

A total of 79 patients with LLFTB were included. Their mean age was 58.8 years; 46 were male. The clinical, radiographic and laboratory findings were similar in the LLFTB and the control groups, except that the LLFTB patients had less cavitation (P = 0.005). Patients with LLFTB were diagnosed (P = 0.051) and treated (P = 0.001) later than the control patients. The calibres of the trachea and both main bronchi were significantly smaller in the LLFTB group (P < 0.001). More patients with LLFTB developed segmental or lobar atelectasis during follow-up (P = 0.028).

The manifestations of LLFTB are non-specific. The lower-lung involvement, the lower incidence of cavitation and the higher probability of segmental or lobar atelectasis implied that LLFTB was primary TB. A small bronchial calibre probably contributed to its development.