Right heart failure due to benign metastasizing leiomyoma: a case report of this exceedingly rare condition and review of the literature

Background Benign metastasizing leiomyoma (BML) is a smooth muscle tumour of genital origin occurring in women with a history of uterine or pelvic leiomyoma. Although histologically benign, it exhibits metastatic behaviour. Lungs are the most common site of metastasis. The heart is a rare site and metastasis at this location has been described in just few cases. Case summary A 42-year-old woman with a resected uterine leiomyoma and a subsequent and still not-resected left periovarian solid mass began complaining of shortness of breath 2 weeks before presentation. Echocardiography showed a mass located in the right ventricular cavity, enlargement of the right ventricle, and severe tricuspid regurgitation. Cardiac magnetic resonance revealed two masses suggestive of tumours in the right ventricle causing right ventricular outflow tract obstruction. Cardiac surgery was performed and, intraoperatively, a third small mass was detected on the tricuspid valve. The masses were resected, and tricuspid valve replacement was performed. Ten days later, the patient underwent an abdominal surgery for the pelvic mass resection. Immunohistochemical analysis of the cardiac and pelvic masses corroborated the diagnosis of benign leiomyomas. The patient was discharged in good clinical condition. Discussion Benign metastasizing leiomyoma to the heart is a rare condition. The pathogenesis remains controversial and includes: (i) vascular or lymphatic spread of myomatous tissue cells when leiomyoma resection or hysterectomy is performed and (ii) smooth muscle cell proliferation in multiple regions. The more usual locations of BML in the heart seem to be the tricuspid valve and the right face of the interventricular septum.