Abstract
Soft tissue sarcomas represent <1% of all neoplasms. Leiomyosarcomas comprise only 5-7% of cases, and only 2% of these are vascular. Vascular leiomyosarcomas are extremely rare and represent only 0.001% of all neoplasms, the venous type being up to 5 times more frequent. Arterial leiomyosarcomas most frequently affect the great vessels, being fatal in most cases. In the reported cases of arterial leiomyosarcomas, the most frequently affected site is the pulmonary artery. We present the clinical case of 2 patients (a 42-year-old woman and a 36-year-old man) with a diagnosis of arterial pleomorphic leiomyosarcoma that conditioned cardiac tamponade as the initial manifestation. As it is an exceptionally rare neoplasm and with few cases reported in the literature, it is important to identify and describe this pathology which, due to the impossibility of offering surgical treatment, represents a therapeutic challenge.