We report the case of a woman in her 60s with intravascular leiomyomatosis. She suffered from numerous non-specific symptoms including weight loss, anaemia and sudden swelling of the left lower extremity. CT imaging showed the presence of an enlarged left ovary and a thrombus extending from the left ovarian venous plexus intruding into the right atrium of the heart. Cancer antigen 125 was 20 U/mL. Pelvic transvaginal ultrasound examination identified two normal ovaries and a mass adjacent to the left ovary. A second opinion on the CT scan was requested at a oncogynaecological multidisciplinary team meeting, where the radiologist of the team identified an intervascular leiomyomatosis. After further investigation, surgical treatment was planned and completed in collaboration with the departments of cardiothoracic and vascular surgery. The patient recovered fully.