Biopsy
A definite and direct approach to diagnose TBP involves identifying acid-fast bacilli (AFB) in any body site. But the long waiting time limits its value in clinical decision. A pericardial biopsy may be helpful for diagnosing TBP. Typical histology with caseous necrosis and granulomatous inflammation or positive AFB staining can confirm the Diagnosis. However, when the progression comes to the end-stage, typical microscopy findings can disappear, and left only fibrotic changes and chronic inflammation. So the Diagnosis of TBCP should be made early or the etiology of the disease should be clear at the early stage. Once the Diagnosis of the restriction has been made, establishing a TB etiology is less straight forward, for a large proportion of patients present restriction but have no prior history of TB[53,54]. So the response to anti-tuberculosis treatment should be another criterion of the Diagnosis of TBCP.
The most challenging aspect of the Diagnosis of TBCP (Figure.4) remains to be establishing a tubercle bacilli etiology, especially in countries in which TB is not endemic. For those patients with TBCP who developed from TBP, the Diagnosis is relatively simple. Although there are four stages of TB (dry, effusive, absorptive, and constrictive), TBCP may not always result from the progression of acute pericarditis from a dry stage sequentially through an effusive, and absorptive, but may mainly result from a fibrotic pericardium without previous history of acute pericarditis. What’s more, the clinical presentation of constriction is highly variable, which may range from asymptomatic to severe constriction. When the disease has reached the advanced stage and the constriction has formed, finding the etiology may be hard, for the typical caseous necrosis has disappeared. Therefore, whether in the endemic area and history are vital to the Diagnosis of TBCP. Pericarditis-related diseases or procedures such as TB, HIV, T2DM, obesity, chest radiotherapy, SLE, uremia, infecting by viral, and a history of heart surgery and so on should be mastered, which can help us make a faster and accurate diagnosis. Also, we should pay attention to the differences in the Diagnosis of TBCP accompanied by HIV or T2DM and TBCP caused by MDR-TB or XDR-TB.