Radiological features and progression of incipient active pulmonary tuberculosis according to risk factors.

<sec> <title>OBJECTIVES</title> To examine the radiological features of incipient active pulmonary tuberculosis (PTB) in humans and evaluate radiological progression according to risk factors. </sec> <sec> <title>DESIGN</title> We retrospectively included 66 non-human immunodeficiency virus patients with bacteriologically proven PTB who had diagnostic and incidental pre-diagnostic computed tomography (CT) scans. CT scans were reviewed using a scoring system that included typical and atypical abnormalities associated with PTB. Risk factors for progression were assessed and, based on these, the CT features and progression of TB were compared using regression analyses. </sec> <sec> <title>RESULTS</title> The most prevalent CT finding in incipient PTB was a well-defined solid nodule in upper lobes and lower lobe superior segments. The non-risk and at-risk groups did not differ in terms of the proportion of individuals with nodules and segmental location. The at-risk group had a higher incidence of progression (adjusted odds ratio 8.59), greater increment in the CT score (adjusted regression coefficient [aRC] 9.19) and a higher proportion of atypical CT abnormalities on diagnostic CT scans (aRC 13.15). </sec> <sec> <title>CONCLUSION</title> Incipient active PTB primarily manifested as a small nodule in humans regardless of risk factors. With risk factors, it progressed more frequently and rapidly into active disease, with a higher prevalence of atypical radiological manifestations. </sec>.