Unmasking Tuberculosis Pericarditis: The Role of Xpert MTB/RIF in Early Diagnosis and Treatment-A Case Report.

Tuberculous pericarditis (TBP) is an uncommon but serious form of extrapulmonary tuberculosis that remains diagnostically challenging due to its nonspecific clinical features and the limited sensitivity of conventional methods such as smear microscopy, culture, and histopathology. We describe an 80-year-old man presenting with recurrent fever and weakness, found to have a large pericardial effusion with tamponade physiology requiring emergent pericardial window drainage. Pericardial fluid analysis demonstrated an exudative, lymphocyte-predominant effusion with elevated lactate dehydrogenase and low glucose levels, but initial acid-fast bacillus smear, histopathology, and sputum studies were negative. Xpert MTB/RIF testing performed on pericardial fluid detected Mycobacterium tuberculosis, enabling early initiation of antitubercular therapy prior to culture confirmation. This case underscores the importance of considering TBP in patients with unexplained pericardial effusion, particularly in those with epidemiologic risk factors, and highlights the diagnostic value of Xpert MTB/RIF as a rapid and highly specific molecular assay that can expedite diagnosis and improve clinical outcomes.