CT Scan Differences of Pulmonary TB According to Presence of Pleural Effusion

Background Subpleural micronodules and interlobular septal thickening are common computed tomography (CT) findings in tuberculous (TB) pleural effusion. These CT features could help us differentiate between TB pleural effusion and non-tuberculous empyema. Research Question Does the frequency of subpleural micronodules and interlobular septal thickening correlate with the presence of pleural effusion in patients with pulmonary TB? Study Design and Methods CT findings of pulmonary TB, micronodules and their distribution (peribronchovascular, septal, subpleural, centrilobular, and random), large opacity (consolidation/macronodule), cavitation, tree-in-buds, bronchovascular bundle thickening, interlobular septal thickening, lymphadenopathy, and pleural effusion were retrospectively analyzed. Patients were divided into two groups according to the presence of pleural effusion. Clinicoradiological findings of the two groups were then analyzed. We presented Benjamini-Hochberg critical value for multiple testing correction of CT findings with false discovery rate of 0.05. Results Of a total of 338 consecutive patients diagnosed with pulmonary TB who underwent CT scans, 60 were excluded due to co-existing pulmonary diseases. The frequency of subpleural nodules (47/68, 69% in pulmonary TB with pleural effusion vs. 30/210, 14% in pulmonary TB without effusion, p < 0.001, Benjamini-Hochberg (B-H) critical value = 0.0036) and interlobular septal thickening (55/68, 81% vs. 134/210, 64%, p = 0.009, B-H critical value = 0.0107) was significantly higher in the group of patients with pulmonary TB with pleural effusion than in the group without pleural effusion. In contrast, tree-in-buds (20/68, 29% vs. 101/210, 48%, p = 0.007, B-H critical value = 0.0071) were less frequently seen in patients with pulmonary TB with pleural effusion. Interpretation Subpleural nodules and septal thickening were more common in pulmonary TB patients with pleural effusion than in those without pleural effusion. TB involvement of the lymphatics in the peripheral interstitium could be associated with the development of pleural effusion.