• acute pericardial disease
• acute idiopathic pericarditis

Acute pericardial disease includes acute pericarditis (friction rub, or characteristic pain and ECG) and cardiac tamponade. The strategy for its aetiologic diagnosis can be quite simple, because it is either associated with other conditions (such as myocardial infarction, collagen vascular disease, uraemia, or neoplasia) which give the correct clue to aetiology or, when presenting in isolation in developed countries, it is so called idiopathic and usually self limited in most cases. However, in comparatively few instances acute pericardial disease presenting in isolation may be caused by specific treatable diseases (mostly tuberculosis or neoplasia). It may then raise considerable diagnostic problems. Recent developments, such as pericardioscopy,^1,2 and classical procedures such as pericardiocentesis or pericardial biopsy, may appear to be helpful; however, judicious use of invasive diagnostic procedures should always imply a systematic diagnostic reasoning based on the prevalence of specific diagnoses. Although acute pericardial disease can be caused by a vast array of agents or conditions, in immunologically competent patients from the western world most cases unassociated with apparent medical or surgical conditions are secondary to viral infection or the immunological response to it (in about 85% of cases in studies in Spain, for example).^3–,⁵ However, in other parts of the world, some of these causes may have a different prevalence that may accordingly lead to a modified diagnostic approach. Tuberculosis is a case in point.⁶ In affluent countries it is usually rare in immunologically competent people. However, in developing countries or in immunologically compromised patients, it may be a comparatively common pericardial disease, although its true prevalence is unknown. Different prevalences and different patient populations may justify different diagnostic approaches.