Pleural involvement in chronic sarcoidosis detected by thoracic CT scanning

5-10% of patients with sarcoidosis exhibit pleural involvement by standard chest radiograph (CXR) usually associated with chronic advanced lung disease. The frequency of pleural disease in sarcoidosis by chest CT scan is unknown. This study compared pleural involvement by standard CXR with thoracic CT scan and assessed the impact of pleural involvement on pulmonary function tests (PFT) in patients.

The records of 61 consecutive patients seen in the Sarcoidosis Service at Mount Sinai Hospital who had thoracic CT scan, standard CXR, and recent PFT were reviewed.

25 of the 61 patients (41%) had pleural involvement by CT (20 thickening, 5 effusions), compared to 7 (11%) by standard CXR (3 thickening, 4 effusions). Bilateral pleural thickening was more commonly seen in patients with CT evidence of parenchymal fibrosis. On univariate analysis, CT evidence of parenchymal fibrosis and CT pleural thickening were significantly associated with an increased odds of restrictive PFTs, ORs of 7.49 (CI 1.7-31.8) and 4.1 (CI 1.32-12.7), respectively. The association between CT pleural thickening and restrictive PFTs lost significance when adjusted for the confounding effect of parenchymal fibrosis. Restrictive physiology was associated with CT evidence of parenchymal fibrosis even when adjusted for pleural thickening (OR = 5.35 CI = 1.18-24.2).

Sarcoidal pleural involvement as detected by CT scan is much more common than by CXR and is associated with restrictive pulmonary dysfunction. Pleural thickening was also associated with CT evidence of pulmonary fibrosis but not restrictive physiology when adjusted for parenchymal scarring.