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

Abstract

Background: Subpleural micronodules and interlobular septal thickening are common CT scan findings in TB pleural effusion. These CT scan features could help us differentiate between TB pleural effusion and nonTB 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 scan 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. Clinicoradiologic findings of the two groups were then analyzed. We presented Benjamini-Hochberg critical value for multiple testing correction of CT scan findings, with a 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 because of coexisting 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 < .001, Benjamini-Hochberg [B-H] critical value = 0.0036) and interlobular septal thickening (55/68, 81% vs 134/210, 64%, P = .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 = .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.

Keywords: CT scan; lung; pleura; tuberculosis.