Objective: Internal thoracic lymphadenopathy (ITL) has been associated with malignancies and non-tuberculous empyema. However, the association between ITL and active pulmonary tuberculosis (PTB) and the correlation between ITL and other imaging characteristics of active PTB has not been examined.
Materials and methods: A retrospective cohort study comprising 137 adults with active PTB who had a concomitant chest CT over a seven-year period was conducted. Two thoracic radiologists evaluated for ITL as well as nine other imaging characteristics of active tuberculosis, including total lung involvement (as measured by a total severity score), number of nodules, presence of tree-in-bud nodularity, highest extent of tree-in-bud nodularity in a lobe, miliary pattern, cavitary lesions, pleural effusion, lymphadenopathy (excluding internal thoracic lymph nodes), and empyema. The Wilcoxon rank-sum test and chi-squared tests were used to assess the correlation between ITL and additional imaging findings.
Results: Internal thoracic lymphadenopathy was present in 50 of 137 cases (36.5%); most commonly bilateral (19.0%) or isolated on the right side (13.7%), and less commonly isolated on the left side (3.7%). Pleural effusion, lymphadenopathy (apart from internal thoracic compartment), and empyema all showed statistically significant correlations with ITL (p-values of <0.0001).
Conclusions: While the presence of ITL - particularly when accompanied by other imaging findings such as pleural effusion - may prompt a radiologist to first consider malignancy, active PTB should be an additional consideration in the appropriate clinical context.
Keywords: Internal thoracic lymphadenopathy; Tuberculosis.
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