Patients with newly-diagnosed TB are ~20 times more likely to be coinfected with HIV than those without TB. Unfortunately, the diagnosis of TB in HIV-infected patients is often delayed in part related to its atypical presentation¹.

In HIV-infected patients with high CD4 counts, clinical manifestations of TB are usually similar to those without HIV infection (eg, subacute fever, weight loss, cough) with CXR often showing upper lobe infiltrates and/or cavitations typically seen in reactivation TB.

Lower CD4 counts, however, are associated with atypical CXR findings, including pleural effusions, lower or middle lobe infiltrates, mediastinal adenopathy, and lack of cavitary lesions^1,2.  A normal CXR has been reported in 21% of patients with CD4 <200 cells/μl (vs 5% in those with higher counts)².

Advanced immune suppression in HIV infection is also associated with negative sputum smears for acid-fast bacilli, concurrent extra-pulmonary disease, and immune reconstitution symptoms after initiation of anti-TB therapy¹.

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References

1. Kwan CK, Ernst JD. HIV and tuberculosis: a deadly human syndemic. Clin Microbiol Rev 2011;24:351-376. https://cmr.asm.org/content/24/2/351
2. Greenberg, SD, Frager D, Suster B, et al. Active pulmonary tuberculosis in patients with AIDS: spectrum of radiographic findings (including a normal appearance). Radiology 1994;193:115-9. https://pubs.rsna.org/doi/abs/10.1148/radiology.193.1.7916467