A 20-year-old man, with no medical history, was referred to the emergency ward because of severe shortness of breath. Heteroanamnesis revealed that he had suffered influenza-like symptoms for a week, which had become worse in the last 24 h. Physical examination showed a critically ill patient with high fever (body temperature 40°C), tachycardia (pulse rate 110/min), tachypnoea (respiratory rate 35/min), hypotension (RR 100/60 mmHg), and elevated jugular venous pressure; on auscultation diffuse pulmonary crackles were heard. In addition there was a low peripheral oxygen saturation (85 %). Electrocardiography showed sinus tachycardia, with a low voltage of the QRS complex in the limb leads, but was otherwise normal. Meanwhile, the patient’s condition deteriorated which made a transfer to the intensive care unit (ICU) necessary with subsequent invasive mechanical ventilation and treatment with inotropic agents. Also broad-spectrum antibiotics were given, because severe pneumonia was suspected. The main laboratory blood tests revealed a white blood cell count (50× 10/l), CRP (489 mmol/l) and liver enzymes (aspartate aminotransferase/alanine aminotransferase 47/61 U/l, gamma-glutamyl transpeptidase 219 U/l, and alkaline phosphatase 159 U/l) with a disturbed renal function (creatinine 139 μmol/l, glomerular filtration rate MDRD: 57 ml/min/1.73 m, and urea 10.4 mmol/l). At chest X-ray the right lung base showed an air bronchogram with increased attenuation in the right lung base consistent with consolidation. In addition, diffuse bronchial interstitial oedema and cardiac enlargement were present (Fig. 1). Because of these findings, transthoracic echocardiography was performed, showing severe impairment of left ventricular function and pericardial effusion with signs of cardiac tamponade (Fig. 2). Therefore, the patient underwent pericardiocentesis and 800 cc of non-viscous milky fluid was evacuated, immediately leading to haemodynamic improvement. This fluid, which was initially regarded as purulent fluid, turned out to be chyle, because analysis revealed a high concentration of triglycerides and a cholesterol-triglyceride ratio <1. Bacterial analysis of both blood and pericardial fluid (chyle) by culture and broad range polymerase chain reaction analysis (PCR) on various viral pathogens was negative, except for the PCR on Epstein-Barr virus (EBV), which was positive with a higher viral load in the pericardial chyle than in the peripheral blood. Serological analysis suggested a previous EBV infection or a reactivation of the virus, which had caused perimyocarditis, because viral capsid antigen (VCA) IgG and Epstein-Barr nuclear antigen (EBNA) IgG were positive, but VCA IgM remained negative. D. A. A. M. Schellings :M. F. Boomsma :M. J. H. M. Wolfhagen : M. Hijmering :A. R. Ramdat Misier Isala Clinics, Thorax Centre, Zwolle, the Netherlands