Active pulmonary tuberculosis: something old, something new, something borrowed, something blue

Abstract

Tuberculosis remains a major global health issue affecting all countries and age groups. Radiology plays a crucial role in the diagnosis and management of pulmonary tuberculosis (PTB). This review aims to improve understanding and diagnostic value of imaging in PTB. We present the old, well-established findings ranging from primary TB to the common appearances of post-primary TB, including dissemination with tree-in-bud nodularity, haematogenous dissemination with miliary nodules and lymphatic dissemination. We discuss new concepts in active PTB with special focus on imaging findings in immunocompromised individuals. We illustrate PTB appearances borrowed from other diseases in which the signs were initially described: the reversed halo sign, the galaxy sign and the cluster sign. There are several radiological signs that have been shown to correlate with positive or negative sputum smears, and radiologists should be aware of these signs as they play an important role in guiding the need for isolation and empirical anti-tuberculous therapy.

Pulmonary tuberculosis presenting with cluster sign and galaxy sign

“…CS and GS are not necessarily specific to sarcoidosis, and they can also be found in pulmonary tuberculosis, although less frequently than in sarcoidosis 5 6. However, CS and GS in pulmonary tuberculosis correlate with lower isolation of M. tuberculosis 6 7. It has also been reported that smaller CSs are often non-caseous granulomas 3.…”

Technical Quality and Diagnostic Impact of Chest X-rays in Tuberculosis Screening: Insights From a Saudi Teleradiology Cohort

“…The general good health status of the migrant workforce population may influence this outcome. Moreover, the classic radiographic signs of active TB, such as consolidations, cavitations, and pleural effusions, are often distinctly visible on chest X-rays [ 14 , 15 ], facilitating diagnosis despite technical limitations. In our study, incidental findings unrelated to active TB have been only noted in 4% of the cases, with only 1% being clinically relevant.…”

An undiscussed distribution of chest X-ray findings in pulmonary tuberculosis

“…The disease spread in PTB can occur endobronchially, through the lymphatics or through the blood vessels [7]. Therefore, we predict that pathophysiology of the occurrence is due to the asymmetry of any of them, either alone or in combination.…”