Rare Left Atrial Undifferentiated Pleomorphic Sarcoma with Brain Metastasis in an 18-Year-Old Patient

Background Primary cardiac undifferentiated pleomorphic sarcomas are extremely rare and frequently present after metastasis. They are associated with a poor prognosis and often require multidisciplinary treatment. Due to their rarity, especially in young patients, they are often misdiagnosed. Case Summary An 18-year-old male presented with progressively worsening headaches, nausea, blurry vision, and diplopia. Computed tomography of the head demonstrated a large brain lesion, and same-day imaging of the thorax incidentally revealed a large left atrial mass. Surgical resection of his brain lesion demonstrated undifferentiated cellular pathology. A multidisciplinary team determined that the left atrial mass was likely the primary source of his brain lesion. Despite proven metastatic disease, the patient was taken to the operating room for palliative resection of the cardiac sarcoma. The invasiveness of the tumor limited the procedure to an R 1 resection. The patient subsequently underwent Gamma Knife radiotherapy for his brain lesion and adjuvant systemic chemotherapy. Conclusion Primary cardiac undifferentiated pleomorphic sarcomas are often diagnosed after metastasis and are prone to being misdiagnosed in otherwise young, healthy patients. We present a case of undifferentiated pleomorphic cardiac sarcoma in an 18-year-old that presented with neurologic symptoms which highlights the need for broad differentials, thorough work-up, and multidisciplinary coordinated care.