211: PRIMARY PERICARDIAL SARCOMATOID MESOTHELIOMA PRESENTING AS CARDIAC TAMPONADE

Introduction: Primary pericardial mesothelioma (PPM) is a rare tumor of mesothelial cells in the pericardium with an abysmal prognosis. Diagnosis is challenging. This case highlights diagnosis of sarcomatoid PPM presenting as cardiac tamponade. Description: A 74-year-old male presented with abdominal pain, emesis, recent syncopal events, ascites, and anasarca. His heart rate was 107 bpm and blood pressure was 95/59 mmHg on presentation. Broad spectrum antibiotics, vasopressors, and intravenous fluids were started for undifferentiated shock. Echocardiography showed large pericardial effusion with tamponade. Emergent pericardiocentesis revealed 260cc of bloody fluid but was non-diagnostic. Chest CT showed bilateral pleural effusions and diffusely thickened pericardium with calcifications, but no mass. Right heart catheterization was consistent with constrictive pericarditis. Cardiac MRI showed large pericardial effusion with early tamponade physiology, diffuse pericardial thickening, irregularity, and calcifications. Cardiothoracic surgery performed pericardiectomy; large bloody effusion was again removed. Intraoperative tissue cytology showed atypical mesothelial cells. Vasopressors were restarted post-operatively, he improved and was ultimately discharged home on post-operative day 11. He was readmitted one week later with shock, altered mental status, and renal failure. Pericardial biopsy results returned positive for sarcomatoid PPM. He was enrolled in hospice and passed 3 weeks later. Discussion: PPM comprises 1% of all mesotheliomas with a prevalence less than 0.0022%. Only 10-20% of cases are diagnosed antemortem. Symptoms are insidious, nonspecific, and related to pericardial effusion; initial presentation of cardiac tamponade is rare. Pericardial mesothelioma, unlike pleural, is not linked to asbestos exposure. Pleural fluid is diagnostic in only 10-30% of cases. Surgical biopsy is often needed for diagnosis. PPM is classified into 3 histological types: epithelioid, biphasic, and sarcomatoid, with the latter being rarest. Median survival time is 6 months from diagnosis. Surgical resection has no survival benefit but can relieve constriction of the heart. Platinum-based chemotherapy +/- pemetrexed is associated with improved survival and can be considered if aggressive care is sought.