Primary malignant pericardial mesothelioma (PMPM) is a rare cardiac tumor. The patient usually presents with pericardial constriction, usually misdiagnosed and wrongly managed. We present the case of a 21-year-old woman with a history of pericarditis and cardiac tamponade. The patient was referred from a clinic due to nausea, vomiting and ascites with lower extremity edema, soft and watery diarrhea, and right upper quadrant pain. Surgery (sternotomy and partial pericardiectomy) was proposed after looking at the different relevant investigations; it was not until that the patient was operated on that it was established that this wasn't a mere constriction but a malignancy. The patient shortly died after the operation. Pathology made a diagnosis of PMPM. Along with the classical symptoms those who present with level 1 thoracic adenopathy a decision to operate should be very carefully made, this may lead to a misdiagnosis of PMPM which postoperatively results in patient's death.