Abstract 14362: A Case of a Primary Malignant Pericardial Myxoid Sarcoma in a Young Adult

Introduction: Primary pericardial malignant tumors are rare clinical entities with an incidence of 0.001%. The symptoms depend on the location and size of the mass, typically causing chest pain, dyspnea, or syncope. We present the case of a young man with atypical chest pain, rapidly progressing to cardiac arrest from a primary pericardial myxoid chondrosarcoma. Case Presentation: A 31-year-old man presented with atypical chest pain. Subsequently, he had a cardiac arrest with pulseless electrical activity. CT chest revealed a 9.5 x 10 cm epicardial mass (Figure 1a, 1b) found to be a myxoid sarcoma on CT-guided biopsy. The morphology was suggestive of a high-grade extra-skeletal myxoid chondrosarcoma. Cardiac MRI had normal function and no myocardial invasion. The staging MRI did not show any other primary source. Due to the large size of the mass, a decision was made to perform surgical resection. Most of the tumor was excised but had positive margins from the part adherent to the inferior vena cava. In the absence of clear guidelines, multiple chemotherapy regimens including doxorubicin, ifosfamide, and etoposide were tried. The initial response was complicated by eventual recurrence and metastasis to the chest wall and mediastinum (Figure 1c, 1d). Further, genetic testing with next-generation sequencing demonstrated MAP3K1 gene mutation. As MAP3K1 mutations have shown sensitivity to MEK inhibition, targeted chemotherapy with trametinib was initiated in combination with pazopanib, a multikinase inhibitor. With the progression of metastatic disease despite treatment, the patient decided to pursue palliative care. Discussion: Malignant pericardial myxoid chondrosarcoma is a rare tumor that may lead to fatal outcomes in young adults. Despite numerous surgical and chemotherapeutic interventions, they have a guarded prognosis. Increased clinician awareness and a wide differential while evaluating cardiac masses are key for early detection and timely treatment.