Abstract
BACKGROUND: A pleural fluid adenosine deaminase (ADA) has been used globally to assist in the diagnosis of a tuberculous pleural effusion (TPE) with a notable negative predictive value. CASE PRESENTATION: We report a case of a patient with a negative pleural fluid ADA who was found to have culture-positive and biopsy-proven Mycobacterium tuberculosis. CONCLUSIONS: This case shows the importance of pursuing gold standard diagnostic studies when clinical suspicion remains high despite negative preliminary testing. We further describe gaps in research to improve pleural fluid biomarkers for TPE.