BACKGROUND: Angiosarcoma is a rare and aggressive vascular tumor that often presents diagnostic and therapeutic challenges. Its potential for misdiagnosis emphasizes the importance of a multidisciplinary approach. CASE SUMMARY: A 54-year-old man with Loeys-Dietz syndrome and a history of popliteal artery aneurysm treated with surgical exclusion and autologous vein bypass presented with a recurrent hemorrhage from the popliteal fossa. Despite repeated surgical resection and embolization, persistent bleeding led to diffuse alveolar hemorrhage and respiratory failure. Autopsy confirmed metastatic angiosarcoma with bilateral lung involvement. DISCUSSION: Angiosarcoma is often misdiagnosed due to nonspecific symptoms and overlapping features with benign vascular conditions. This report highlights the rarity, aggressive nature, metastatic potential, and clinically intricate management of popliteal angiosarcoma. TAKE-HOME MESSAGE: This case underscores the importance of considering angiosarcoma in unusual cases of aneurysmal hemorrhage and the need for comprehensive pathology and a multidisciplinary approach for early detection and treatment.
