The Difficulties of Diagnosing a Rare Entity in a Common Situation

Acute purulent pericarditis is rare and more prevalent in the pre-antibiotic era with high mortality, around 40% despite optimal treatment. The diagnosis can be difficult, requiring the practice of a pericardiocentesis in cases with a high index of suspicion. When such a rare entity coincides with another one more frequently the diagnosis can become tricky. We present the case of a man with a previous thoracic surgery who was admitted due to an ST Elevation Myocardial Infarction (STEMI) and was finally diagnosed with Methicillin Susceptible Staphylococcus Aureus (MSSA) purulent pericarditis requiring cardiac surgery. The main difficulty, in this case, was the differentiation between hemopericardium and purulent pericardium. Despite the initial difficulties, the systematic study of febrile syndrome and bacteremia allowed reaching the final diagnosis.