Case Presentation: A 46-year-old male without significant past medical history presented with progressive dyspnea, syncope, and epigastric pain. An electrocardiogram displayed sinus tachycardia without signs of ischemia. A chest radiograph demonstrated a widened mediastinum. A subsequent transthoracic echocardiogram demonstrated pericardial effusion and tamponade. Patient had hypotension that was unresponsive to repeated intravenous fluid boluses, prompting an emergent pericardial window, revealing a 1500 mL hemopericardium. Fluid cytology was negative. A cardiac catheterization revealed patent coronaries with an enhancing mass posterior to the right atrium, supplied by a marginal branch of the right coronary artery. An MRI and PET scan confirmed its presence, with angiosarcoma strongly suspected. However, a biopsy was not done due to the high risk of the procedure and low incidence rate of primary cardiac malignancies; instead, observation was recommended by a tertiary center. Two months later, the patient returned with pleuritic chest pain. A chest radiograph demonstrated pleural effusion and a thoracotomy revealed hemothorax. Fluid cytology was again negative. Repeat chest radiography showed bilateral pulmonary nodules, which were biopsied, confirming angiosarcoma. Distant metastases developed rapidly, and palliative care was pursued. 

Discussion: Primary malignant cardiac tumors are exceptionally rare with an autopsy incidence of 0.0001%. Prompt detection is often missed due to vague presenting symptoms. The most common subtype, angiosarcoma, metastasizes early and carries a grim prognosis with a mean survival of only 6 months. Arriving at an angiosarcoma diagnosis is difficult; especially since fluid cytology is often negative and definitive diagnosis most commonly requires open cardiac biopsy or surgical resection. Common complications of this malignancy include cardiac tamponade, cardiac free wall rupture, heart failure, and additional problems resulting from invasion of surrounding structures. The risk of biopsy should be weighed carefully in each patient to ensure longer survival and improved quality of life.

Conclusions: The importance and significance of this case is to educate on a very rare yet rapidly progressive malignancy. Initial work-up and diagnostic testing in a patient with a suspected primary cardiac tumor should include a transesophageal echocardiogram followed by more specific imaging such as cardiac magnetic resonance imaging. Staging with a positive emission tomography scan and/or a commuted tomography scan is also required for further management in determining if surgical excision would be appropriate. Due to the disease’s rarity, standardized treatment plans have yet to be developed but if possible it has been shown that full surgical resection is the best initial option to improve prognosis. Other treatment options include combinations of chemotherapy, radiation, and/or immunotherapy with mixed results reported in the literature.