A 37-year-old woman, gravida 2, para 1 presented in the outpatient ward with dyspnoea and tachycardia of unknown origin. The physical examination was unremarkable. Echocardiography revealed an intracardiac mass protruding through the tricuspid orifice into the right ventricle during diastole. The patient was admitted to the intensive care unit with the suspicion of vena cava thrombosis with intracardiac expansion. An abdominal sonography showed a mass in the uterus, presumed to be a benign tumour, with extension into the vena cava inferior. Owing to the extent of the mass in the right atrium and the risk for pulmonary embolism, after interdisciplinary discussion, a decision to remove the atrial mass was made. The case was managed by a two-stage procedure. Pathological examination of the intracardiac portions of the tumour revealed a benign tumour that consisted of proliferating smooth muscle fibres without abnormal mitotic activity.