CD4 T lymphocyte count and the radiographic presentation of pulmonary tuberculosis: A study of the relationship between these factors in patients with human immunodeficiency virus infection

Background: Pulmonary infection and tumor in the AIDS population has a variable clinical and radiographic presentation. The association between the radiographic presentation of pulmonary tuberculosis and CD4 T lymphocyte count in the HIV-infected patient is investigated in order to provide an empirical approach for early diagnosis, treatment, and isolation of infected subjects. Methods: A retrospective analysis of chest radiographs, CD4 T lymphocyte counts, and clinical history of 35 subjects from 3 urban hospitals was performed. All subjects were HIV-seropositive and had culture-proven pulmonary tuberculosis. Radiographs were evaluated for the presence of either a pattern characteristic of post-primary tuberculosis (typical pattern) or a pattern uncharacteristic of post-primary infection (atypical pattern). Results: Twenty-one of 26 subjects with a CD4 T lymphocyte count less than 0.20 x 10⁹ cells/L, whereas only 1 of 9 subjects with a CD4 T lymphocyte count of 0.20 x 10⁹ cells/L or more presented with an atypical pattern of pulmonary tuberculosis (p<0.001). The mean CD4 T lymphocyte counts of those subjects presenting with atypical versus typical radiographic pattern of post-primary pulmonary tuberculosis were 0.069 x 10⁹ cells/L (n=22) and 0.323 x 10⁹ cells/L (n=13), respectively (p<0.01). Twenty-one of the 22 subjects with an atypical radiographic pattern of pulmonary tuberculosis were significantly immunosuppressed (CD4<0.20 x 10⁹ cells/L). Atypical radiographic pattern included diffuse and lower lobar opacities, pleural effusion, mediastinal adenopathy, interstitial nodules, and a normal chest radiograph. Conclusion: AIDS patients presenting with CD4 count less than 0.20 x 10⁹ cells/L and an atypical radiographic pattern for pulmonary tuberculosis are at risk for tuberculous infection requiring appropriate treatment and isolation until the diagnosis of pulmonary tuberculosis has been excluded.