Abstract Background Malignant primary cardiac tumors are infrequent and can lead to an unfavorable prognosis if not identified and treated promptly. Early detection and prompt treatment of malignant primary cardiac tumors are crucial for a better prognosis. This article presents a case of primary cardiac leiomyosarcoma and reviews the literature on this topic. Case presentation Female patient that developed recurrent pericardial effusion and hemodynamic instability caused by a cardiac tumor, later identified as leiomyosarcoma. Multidisciplinary treatment was administered to the patient. Conclusions The initial approach to this type of pathology should include multimodality imaging to establish a prompt diagnosis leading to complete standard treatment, to minimize risks to the patient's heart function which may include resection with complete margins of the neoplasm, otherwise the prognosis may be poor.