And second, pleural fluid adenosine deaminase (ADA), which is >35 to 40 U/L in 92% of TB effusions, has been reported to be falsely elevated in 10% of malignancies in general, and nearly 60% of lymphomas in particular.2 Thus, separating TB and lymphomatous effusions may pose a particular challenge and often requires immunophenotyping of lymphocytes into B- and T-cell subgroups (a predominance of small T-cells usually represents a benign process such as TB). Here, ADA is linked to tuberculosis.