Long-term Outcome of Patients With Undiagnosed Pleural Effusion

Introduction: The cause of exudative pleural effusion cannot be determined in some patients. The longterm outcomes of patients with undiagnosed pleural effusion were analyzed.

Methods: Patients with exudative pleural effusion whose diagnostic procedures included pleural biopsy using video-assisted thoracoscopic surgery carried out between 2008 and 2012 were evaluated retrospectively. Patients diagnosed with non-specific pleuritis were included. Fifty-three patients with available follow-up data were included in the study.

Results: Forty men and 13 women (mean age 53.9±13.9 years) were included. Median follow-up time was 24 months. No diagnosis was given in 27 patients (51%), and a clinical diagnosis was given in 26 patients (49%) during the follow-up period. Malignant disease (malignant mesothelioma) was diagnosed in 2 (3.7%) patients. Other diseases were parapneumonic effusion in 12, congestive heart failure in 8, and miscellaneous in 4 patients. Volume of effusion at the time of initial examination and re-accumulation of fluid after video-assisted thoracoscopic surgery were associated with malignant disease (P=.004 and .0001, respectively).

Conclusion: Although the probability is low, some patients with exudative pleural effusion undiagnosed after pleural biopsy via video-assisted thoracoscopic surgery may have malignant disease. Patients with an initially large volume of effusion that re-accumulates after examination should be closely monitored.