Miliary tuberculosis: a comparison of CT findings in HIV-seropositive and HIV-seronegative patients

The aim of this study was to determine the differences in CT findings of miliary tuberculosis in patients with and without HIV infection. Two radiologists reviewed retrospectively the CT findings of 15 HIV-seropositive and 14 HIV-seronegative patients with miliary tuberculosis. The decisions on the findings were reached by consensus. Statistical analysis was performed using the χ² test, Mann–Whitney U-test and Fisher''s exact test. All of the HIV-seropositive and -seronegative patients had small nodules and micronodules distributed randomly throughout both lungs. HIV-seropositive patients had a higher prevalence of interlobular septal thickening (p = 0.017), necrotic lymph nodes (p = 0.005) and extrathoracic involvement (p = 0.040). The seropositive patients had a lower prevalence of large nodules (p = 0.031). In conclusion, recognition of the differences in the radiological findings between HIV-seropositive and -seronegative patients may help in the establishment of an earlier diagnosis of immune status in patients with miliary tuberculosis.Miliary tuberculosis (TB), which results from lympho-haematogenous dissemination of Mycobacterium tuberculosis, is a complication of both primary and post-primary TB 1, 2]. This disease results in the formation of small discrete foci of granulomatous tissue, which are uniformly distributed throughout the lung 3].An increase in TB incidence, including miliary TB, has been associated with infection by human immunodeficiency virus (HIV) 4]. In 2005, the World Health Organization estimated that 12% of HIV deaths globally were caused by TB, and that there were 630 000 new co-infections with TB and HIV 5]. Disseminated TB accounted for 5.4–8.1% of culture-confirmed TB cases, with 10–14% of patients coinfected with HIV having clinically recognisable dissemination 6, 7].Chest radiography may be helpful in the detection and final diagnosis of miliary TB. The characteristic radiographical findings consist of the presence of fine granular or numerous small nodular opacities measuring 1–3 mm in diameter scattered throughout both lungs 1, 3, 8, 9]. However, the radiograph may appear to be normal in the early stage of disease or in cases with nodules below the threshold of perceptibility; therefore, a diagnosis of miliary TB from chest radiographs can be difficult 10].Several studies have shown that CT imaging is more sensitive for the detection of parenchymal abnormalities in patients with AIDS who have active intrathoracic disease, and it has been suggested that CT may also be helpful in the differential diagnosis 11–14]. In addition, it has been reported that certain imaging techniques provided by multidetector-row CT are useful for the diagnosis of multiple micronodular infiltrative lung disease 15]. CT findings of miliary TB have been described in previous reports 16–18]; however, only a few studies on miliary TB in patients with HIV, particularly with reference to the CD4 count, have been reported 19, 20]. The radiographic manifestations of HIV-associated pulmonary TB are thought to be dependent upon the level of immunosuppression at the time of overt disease 21–23].The purpose of this study was to determine the differences in the CT findings of miliary TB for patients with and without HIV infection and to analyse any correlation between the CT features and the level of immunosuppression in patients.