Adenosine deaminase activity in pleural effusions of lymphoma patients

The purpose of this study was to assess the relationship of pleural adenosine deaminase (P-ADA) and non-Hodgkin's lymphoma (NHL).

We retrospectively analysed 63 NHL patients with pleural effusions who accepted a diagnostic thoracentesis and who had P-ADA available at the China Medical University Hospital (Taichung, Taiwan) between January 2003 and April 2012.

There were 46 exudates [40 malignant pleural effusions (MPE), 5 complicated para-pneumonic effusions and 1 undiagnosed effusion] and 17 transudates. The P-ADA activity was significantly different between the two groups (P < 0.005). Among 40 MPE cases, 29 were due to B-cell and 11 due to T-cell NHL. There was no pleural transudative effusion with P-ADA value higher than 26 U/l in our study, but simultaneously 48% (22/46) of exudative pleural effusions showed a P-ADA value under that cut-off point. The P-ADA level reached the diagnostic cut-off for tuberculosis (40 IU/l) in 11 cases of MPE (11/40 = 27.5%): 9 B-cell NHL (9/29 = 31%) and 2 T-cell NHL (2/11 = 18%). The median levels (25th, 75th percentiles) of P-ADA were 28 IU/l (14-50) in the MPE of B-cell NHL and 26 IU/l (14-28) in the T-cell NHL (P = 0.693).

The use of P-ADA in NHL effusion could aid the separation of transudates from exudates. Around one-quarter MPE of NHL had abnormal P-ADA ( > 40 IU/l). There was no difference in the P-ADA activity in T-cell and B-cell NHL.