Abstract
BACKGROUND: Lymphoma-associated malignant pleural effusions (L-MPE) can mimic tuberculous pleural effusion (TPE) characterized by lymphocytic exudate with high adenosine deaminase (ADA) levels. Furthermore, the low cytological yield of L-MPE makes differentiation between L-MPE and TPE more challenging. However, there are few data regarding differential diagnosis of L-MPE and TPE. METHODS: All consecutive patients diagnosed with L-MPE or TPE between January 2011 and December 2016 were retrospectively recruited using the Electronic Medical Record database. Clinical symptoms and laboratory and pleural fluid data [including serum lactate dehydrogenase (LDH), C-reactive protein, and pleural fluid ADA levels] were compared between L-MPE and TPE. Useful variables in the differential diagnosis of L-MPE and TPE were evaluated by multivariate logistic regression analysis. RESULTS: Seventeen patients with L-MPE and 216 patients with TPE were included in this study. In the multivariate analysis, fever was negatively associated with L-MPE [odds ratio (OR): 0.175, 95% confidence interval (CI): 0.033-0.941, P=0.042], while serum LDH levels were positively associated with L-MPE (OR: 1.005, 95% CI: 1.003-1.007, P<0.001). Serum LDH >460 U/L provided a sensitivity of 76% and a specificity of 81% to distinguish L-MPE and TPE. In contrast, serum C-reactive protein and pleural fluid ADA levels were not significantly different between the groups. CONCLUSIONS: Patients with L-MPE and TPE present very similar clinical, laboratory, and pleural fluid characteristics. Fever and serum LDH levels may be helpful in guiding the differential diagnosis of L-MPE and TPE. Lymphoma should be kept in mind in the differential diagnosis in patients with lymphocytic pleural effusion and high ADA levels.