Based on the patient's immunocompromised status (recently diagnosed AIDS), exudative pericardial effusion, pericardial fluid adenosine deaminase (ADA) level >45 U/L [a biomarker with 98% positive predictive value for TB pericarditis in TB-endemic areas (13)], elevated erythrocyte sedimentation rate (ESR), and positive MTB IgG serology (indicating prior TB exposure), he was initially diagnosed with tuberculous pericarditis (TBP). Here, ADA is linked to AIDS.