Primary splenic angiosarcoma is a rare, aggressive malignant neoplasm arising from splenic vascular endothelium. A 70-year-old woman presented with shortness of breath and chest discomfort secondary to a left-sided pleural effusion. A thoracentesis revealed a reactive effusion suspicious for malignancy. Splenic enlargement with heterogeneous enhancement was identified on CT of the abdomen. Laboratory findings at initial presentation revealed mild anemia (10.5 g/dL) with normal platelets (300 × 10⁹/L). Laparoscopic splenectomy was performed, and a primary splenic angiosarcoma was discovered. After 2 rounds of chemotherapy, a CT scan showed progressive disease with metastasis to the liver and lung. The patient's antineoplastic regimen was switched to Ifosfamide and Doxorubicin. She is currently alive with evidence of disease at 9 months but without further progression. Primary splenic angiosarcoma is almost universally fatal despite treatment. The best chance for survival is early diagnosis and prompt splenectomy prior to splenic rupture.